awake experiment

Laser Beam Transport and Integration.

AWAKE Collaboration meeting.

Mikhail MartyanovChristoph Hessler CERN, EN-STI-LPValentin Fedosseev

CERN 09-11.04.2014

M.Martyanov, CERN 210.04.2014

AWAKE Experiment

Laser room

e-gun room

p+ beam

e- beam

laser beam

Laser safety shutters

Laser shutters

Fast valves

plasma

e- spectrometer

Laser dump

p+ / e-

diagnostics

CV

SAS

AWAKE gallery

Control room 1km

Laser / p+ merging point

M.Martyanov, CERN 3

Overview

• Short intense laser pulse is needed for:– to create a 100% ionized plasma– moving ionization front is a source of perturbation for proton-laser

instability (micro-bunching and wake-field with a stable phase)

• Plan for the Laser system:– First it is delivered to MPP Munich for plasma experiments - mid 2014– Then it goes to CERN - Autumn 2015

10.04.2014

M.Martyanov, CERN 4

Overview• Laser system comprises:

- laser with 2 beams (for plasma and for the e-gun)- delay line is possible in either one of these beams- focusing telescope (lenses, in air), long 40m focusing- optical compressor (in vacuum)- small optical in-air compressor

and 3rd harmonics generator for e-gun

• Laser parameters for plasma:- max energy 450 mJ- pulse duration 120 fs after compression- max beam diameter 40 mm

Only reflective opticson the way

Rule of thumb (B<1):I[GW/cm2]L[cm]<36

10.04.2014

M.Martyanov, CERN 5

Laser System Base-line

• Laser, Telescope and Compressor are in the laser room• Focusing down to 40 meters to the center of the plasma

• Back solution: Compressor and Telescope are next to merging point in the proton tunnel

• Focusing down to 25 meters to the center of the plasma• Question is if this possible?

Crucial points are:• Focusability of the laser beam down to 40 meters, ionization dynamics, diffraction?• No detailed information on the laser system yet (beam quality)• The placement of the optical compressor and the focusing telescope has an impact on

the position of the anew drilled connection tunnel• Availability of vacuum components for the compressor and telescope is under study.• 10-6 Torr “easily” achievable. Pellicle or differential pumping as an option to go better

10.04.2014


Scope of Laser Line WP• Laser room preparation

- Clean room, cooling and ventilation, facilities- Access control

• Laser transfer line to the plasma cell- HV vacuum line- Remote control of the mirrors- Laser beam position monitoring

• Laser transfer line to the photo-gun- Fore-vacuum line- Remote control of the mirrors- Laser beam position monitoring- In-air compressor and 3rd harmonic generation <- Electron source WP

• Laser installation- Laser arrangement on the tables- Integration to the AWAKE environment

M.Martyanov, CERN 7

1mcompressor

2 x 1 m

optical table

SAS

CVunits

4m 3m

0.9m

2 x 1 m

optical table

2.5 x 1 m

optical table

2.5 x 1 m

optical table

Arrangement in the Laser Room

Fore-vacuum laser transfer line for e-gun(on the ceiling)

10.04.2014

PP+ power supply600x600x(H)850

CCM rack700x800x(H)1400

~1m

M.Martyanov, CERN 8

1

6

53

4

2

8

7

Three optical tables: 2x1, 2.5x1, 2.5x1 m

1 – MENLO oscillator, 500x5002 – Stretcher, 1000x5003 – Regen / preamp, 1000x800 4 – Green pump for (3)5 – 600mJ amplifier, 1500x8006 – Green pump for (5), 500x2007 – Focusing telescope, 1000x2008 – Delay line for e-gun

Laser Arrangement on the Tables

10.04.2014

M.Martyanov, CERN 9

4.000 m3/h

F 30 Pa 15 Pa 0 Pa

Technical Room Laser Room SAS

4 m 14 m 2 m

• CV technical room already quite small. Other solutions?• Access to CV technicians in the clean room for M&O.• Very dry air from surface -> comfort and electronics?

Laser room air-conditioning principal(by Michele Battistin)

10.04.2014

M.Martyanov, CERN 10

Fresh air supply from surface

Air supply duct to the clean

room

Air extraction to TCV4

CV first integration(by Michele Battistin)

10.04.2014


Laser Room – Integration 3D Model(by Frederic Galleazzi)


TT41 – Laser Beam – Civil Engineering(by Frederic Galleazzi)

10.04.2014

Safety laser shutter

Vacuum pump

Vacuum shutter

Laser shutter


Mirror Chambers Preliminary Design(by Nicolas Chritin)

10.04.2014


Laser beam is not centered on the mirrorin horizontal plane, but centered in vertical.

The gap between beams is 21-6-13=2mmThe gap between proton beam and a mirror is 1mm

50

2637

Footprintof the laser beam

on the mirror37=26sqrt(2)

Laser beam 26

Mirror 50, S=12Fused silica

Proton beam 12

Beams separation

21mm

Tow

ards

the

plas

ma

p+ from SPS

10.04.2014

Laser and p+ merging


Laser Beam Size Downstream Merging(not to scale)

Laser beam 26 @ merging

Mirror 50, S=12Fused silica

Proton beam 12

Beams separation

21mm

p+ from SPS

Plasma cell

20m 10m 20m

26

Additional laser shutters

Fast valves Laser dump

Be-window for p+Experimental area

Laser Safety Shutter


System To define / To doLaser room, SAS, CV Air circulation, conditioning, humidity, filters, circuits (electrical,

demineralized water, tap water, compressed air, control cables), safety (fire/smoke alarm), shutters, access etc.

Connection tunnel 40cm Drilling, position has been definedAccess to laser room and p-tunnel

AWAKE access concept including Laser Access Modes to p-tunnel and e-gun room, safety shutters

Ti:Sa laser Laser arrangement on three tables to be defined by AMPLITUDE. Arrangement of chillers and electronics – to be definedControls and diagnostics are provided by AMPLITUDEDetailed specification is required

Vacuum pulse compressor and focusing telescope.

Who supply compressor chamber ?Vacuum agreed to be 1e-06mbar in the compressor

Transfer line to p-tunnelMerging point chamber

To be designed, work has been started

Transfer line to e-gunSeparate small compressor3rd harmonic generation

In fore-vacuum, to be designed

Laser installation in laser room

10.04.2014


System IssuesLaser beam in the p-tunnel Steady diagnostics:

Focused beam spot monitor (virtual plasma, the same long distance run); near field before merging mirror; screens before and after plasma tube sensitive to “both” beams (laser, electrons, protons) also equipped with fiber-coupling for rough timing measurementsOn demand or maintenance diagnostics:Auto-correlator, angular spectrometer, phase-front detector, etc.

Laser beam in the e-gun room(small compressor and 3rd harmonic generation are next to the gun)

Steady diagnostics:Virtual cathode CCD, UV energy meter, some IR signal coupled to a fiber for rough timing measurementOn demand or maintenance diagnostics:Auto-correlator, angular spectrometer, …

Delay control between pulses: ionization and e-gun

Delay line either on one of 2 beams, proper delay simulation required.Split after RegAmp was proposed by AMPLITUDE with 2.5mJ IR output for e-gun

Laser installation in p-tunneland in e-gun room

10.04.2014


Thank you!

10.04.2014


4.000 m3/h

F

30 Pa 15 Pa 0 Pa

Technical Room Laser Room SAS

2 m ! 15 m 3 m

• CV technical room already quite small. Other solutions?– Make it even smaller !

• Access to CV technicians in the clean room for M&O– Assume it is a rare event !

• Very dry air from surface -> comfort and electronics?– Poor comfort (manageable), for electronics – to be considered

Laser room air-conditioning principal(our proposal)

10.04.2014

Attenuated energy optionMax 280 mJ

Full energy focusing optionMax 450 mJ

z, m

r, m

m

Flux W [J/cm2], Ith = 1.7 TW/cm2, Wth = 0.2 J/cm2E0 = 100 mJ, Wmax = 1.54 J/cm2, Imax = 12.1 TW/cm2

0 10 20 30 40 50 60 70 80

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5 0

0.5

1

1.5

z, m

r, m

mFlux W [J/cm2], Ith = 1.7 TW/cm2, Wth = 0.2 J/cm2

E0 = 100 mJ, Wmax = 5.24 J/cm2, Imax = 41.0 TW/cm2

0 10 20 30 40 50 60 70 80

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

z, m

r, m

m

Flux W [J/cm2], Ith = 1.7 TW/cm2, W th = 0.2 J/cm2E0 = 100 mJ, Wmax = 10.07 J/cm2, Imax = 78.8 TW/cm2

0 10 20 30 40 50 60 70 80

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

1

2

3

4

5

6

7

8

9

10

Plasma hereLast turning mirror

Very smooth focusingMax 100 mJ

Focusing geometry, 40 meters

Simple propagation of a super-Gaussian beam, no plasma

z, m

r, m

m

Flux W [J/cm2], Ith = 1.7 TW/cm2, W th = 0.2 J/cm2E0 = 100 mJ, Wmax = 5.46 J/cm2, Imax = 50.1 TW/cm2

0 10 20 30 40 50 60 70 80

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

z, m

r, m

m

Flux W [J/cm2], Ith = 1.7 TW/cm2, Wth = 0.2 J/cm2E0 = 100 mJ, Wmax = 5.46 J/cm2, Imax = 50.1 TW/cm2

0 2 4 6 8 10

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

z, m

r, m

m

Ionization ratio P, Ith = 1.7 TW/cm2, W th = 0.2 J/cm2E0 = 100 mJ, Wmax = 5.46 J/cm2, Imax = 50.1 TW/cm2

0 2 4 6 8 10

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Focusing geometry, 40 metersAttenuated energy option, Super-Gaussian beam ionizing plasma, 100mJ pulse

Ionization ratio in plasmadE = -30mJ

awake experiment

Documents

egun laser parameters

plasma experiments mid

compression max beam

max energy

optical compressor

air compressorand

cern autumn

mj pulse duration