Imperial College London 1

2 Particle sources 1 Electron sources

Thermionic sources

Field emitters

Laser sources

2 Ion sources

21 Production of high currents of single charge state ion beams

Penning sources

Hot cathode sources

RF sources

22 Production of high charge state ions

ECR sources

EBIS sources

Laser sources

Imperial College London 2

2 Particle sources

23 Production of negatively charged ion beams

Surface Production

Volume Production

3 Extraction of particle beams

31 The space charge limit and Child-Langmuirs law

32 External and internal fields in the extractor laminar flow and pierce angle

33 The beam emittance the acceptance of the extraction system and the conservation of phase space

Imperial College London 3

Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the

Upper levels of the ldquoelectron gasrdquo in solids This can be done by

1) Thermionic emission

The heated electron must

have an energy higher than

the workfunction

2) Photoemission

The photon energy must

exceed the work function

3) Field emission

high external electric fields

alter the potential barrier

and allow electrons to be

extracted by the tunneleffect

Imperial College London 4

Current density as a function of Binding energy and temperature

Material A (eV) Temp (deg K) J (Acm2)

Tungsten 60 454 2500 03

Thoriated W 3 263 1900 116

Mixed oxides 001 1 1200 1

Caesium 162 181

Tantalum 60 338 2500 238

CsOW 0003 072 1000 035

Richardson-Dushman equation

curr

en

t

Diode characteristic

Temperature limited

Space charge limited

voltage

kTo

eTAJ

2

Imperial College London 5

Thermionic guns

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 2

2 Particle sources

23 Production of negatively charged ion beams

Surface Production

Volume Production

3 Extraction of particle beams

31 The space charge limit and Child-Langmuirs law

32 External and internal fields in the extractor laminar flow and pierce angle

33 The beam emittance the acceptance of the extraction system and the conservation of phase space

Imperial College London 3

Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the

Upper levels of the ldquoelectron gasrdquo in solids This can be done by

1) Thermionic emission

The heated electron must

have an energy higher than

the workfunction

2) Photoemission

The photon energy must

exceed the work function

3) Field emission

high external electric fields

alter the potential barrier

and allow electrons to be

extracted by the tunneleffect

Imperial College London 4

Current density as a function of Binding energy and temperature

Material A (eV) Temp (deg K) J (Acm2)

Tungsten 60 454 2500 03

Thoriated W 3 263 1900 116

Mixed oxides 001 1 1200 1

Caesium 162 181

Tantalum 60 338 2500 238

CsOW 0003 072 1000 035

Richardson-Dushman equation

curr

en

t

Diode characteristic

Temperature limited

Space charge limited

voltage

kTo

eTAJ

2

Imperial College London 5

Thermionic guns

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 3

Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the

Upper levels of the ldquoelectron gasrdquo in solids This can be done by

1) Thermionic emission

The heated electron must

have an energy higher than

the workfunction

2) Photoemission

The photon energy must

exceed the work function

3) Field emission

high external electric fields

alter the potential barrier

and allow electrons to be

extracted by the tunneleffect

Imperial College London 4

Current density as a function of Binding energy and temperature

Material A (eV) Temp (deg K) J (Acm2)

Tungsten 60 454 2500 03

Thoriated W 3 263 1900 116

Mixed oxides 001 1 1200 1

Caesium 162 181

Tantalum 60 338 2500 238

CsOW 0003 072 1000 035

Richardson-Dushman equation

curr

en

t

Diode characteristic

Temperature limited

Space charge limited

voltage

kTo

eTAJ

2

Imperial College London 5

Thermionic guns

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 4

Current density as a function of Binding energy and temperature

Material A (eV) Temp (deg K) J (Acm2)

Tungsten 60 454 2500 03

Thoriated W 3 263 1900 116

Mixed oxides 001 1 1200 1

Caesium 162 181

Tantalum 60 338 2500 238

CsOW 0003 072 1000 035

Richardson-Dushman equation

curr

en

t

Diode characteristic

Temperature limited

Space charge limited

voltage

kTo

eTAJ

2

Imperial College London 5

Thermionic guns

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 5

Thermionic guns

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 6

Field emission of electrons from surfaces

Fowler Nordheim

J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)

EeEBJ

51071086

2

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 7

Field emission of electrons from surfaces

Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams

Field emitter arrays designed for the production of large panel plasma screens

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 8

Photo effect

20 2

1vmEE

chfhE electronkinpot

lightlightphoton

free electrons

bound electrons

light

uv- lampzinc-plate

glass

f

photo cathodeLight ()

ring anode

+ -IpA

U (I=0) U

h

f

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 9

Photo effect and laser sources

2390 Laser

Laser

r

QEPJ

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 10

Photo effect and laser sources

DESY PITZ 2 source (LC XFEL)

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 11

Production of high currents of single charge state ion beams

For efficient ion production the electron energy should be app 2-4 times the

ionization energy of the ion

The impact of electron with gaseous atoms is mostly used for the

production of ion beams

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 12

Production of high currents of single charge state ion beams

A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas

discharge and to enhance plasma confinement magnetic fields are used

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 13

Penning sources

The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement

The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end

The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 14

Magnetron sources

The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 15

Hot cathode sources

Filament Ion Source

Discharge in the plasma chamber is driven by the electrons delivered by the filament

1048774single charged ions up to 100 mA

bull Plasma enclosure by magnets

bull Pressure range 10-1 - 10-3 mbar

bull Discharge voltage 20 - 200 V (depending on ionization

voltage)bull Discharge current 10 - 500 A

100 m m

copperiso lator

w ater

steel

brass

m agnets

ground-electrode

screening-e lectrode

plasm a-electrode

B x

B z

C oSm -m agnets

gasin le tcathode

solenoid

filter-m agnet

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 16

RF sources

Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)

but high beam currents possible

Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 17

RF sources

Production of large ion currents (Igt1 A) of single charged ions for surface

treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure

External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 18

Production of high charge state ions

The PLASMA created is increased in density by electron

bombardment The maximum charge state that will be obtained depends on the incident electron energy

e + X = X+ + 2e

For multi-charge states

e + X i+ = X (i+1)+ + 2e

higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron

energy

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 19

Electron Cyclotron Resonance Sourcehf = cyc = (em) B

Radial and axial magnetic field distribution for the confinement of the source plasma

Only at the centre of the source the cyclotron condition for the electrons is full filled

(01-1 kW)

Extracted ion currents for different charge states of Argon

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 20

Electron Cyclotron Resonance source

By variation of the longitudinal enclosing magnetic mirror configuration the

charge distribution can be influenced

Schematic layout of an ECR source for the production of radioactive

ion beams

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 21

Electron Beam Ion Source

nominal valuesmax

valuesunits

electron beam current 350 1300 mA

electron beam energy 20 275 keV

trap length 12 - m

magnetic field 15 5 T

charge per pulse 1-2 4 nC

ion pulse length 005-100 - micros

containment time 20-2000 - ms

Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV

17 cm

CRYogenic Stockholm Ion Source

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 22

Electron Beam Ion Source

Ion current extracted from an EBIS as a function of the

charge state for Na ions (Ne gas was added)

Comparison of the extractable (electric)

current between ECR and EBIS

Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 23

Laser Ion Sources

Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands

in the drift chamber and then is accelerated in the extraction gap

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 24

Laser Ion Sources

The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap

By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 25

Laser Ion Sources

The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma

The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 26

Production of negatively charged ion beams

Three Types of H- Ion Sources are in use

bull Surface conversion sources

bull Volume production sources

bull Hybrid production sources

Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)

Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr

Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment

Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 27

Production of negatively charged ion beams

anode

cathode

gasin let solenoid filter

extractore -gtHslow

-driver

e -gtHfast 2

Magnetic dipole fields can be used as filters

to create areas of different electron

temperatures

Cross sections for different production

and destruction mechanisms

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 28

Sources using surface production

Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation

Picture of the LANCE surface source

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 29

Sources using volume productioncopperm agnetiso latorwater

plasm a-cham ber

plasm a-electrode

screening-e lectrode

electron-dum ping

solenoid bending-m agnet

soleniod

cathodeand

gasin let

filter-m agnet

grid

The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface

cover for the reduction of the dissociation of the H2 molecules

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 30

Sources using hybrid production schemes

The RAL H- source uses a Penning discharge (dipole for plasma

production and to influence electron temperature) and Cs injection

The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 31

The extraction of particle beams

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 32

The space charge limit and Child-Langmuirs law

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 33

The space charge limit and Child-Langmuirs law

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 34

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 35

External and internal fields in the extractor laminar flow and pierce angle

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 36

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 37

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space

Imperial College London 38

The beam emittance the acceptance of the extraction system and the conservation of the phase space