No.1

US-J Workshop2005, in Japan

Beam-Target Interaction for Heavy Ion Fusion

T.Someya, K.Miyazawa, T.Kikuchi, S.KawataUtsunomiya Univ., Japan

A.I.OgoyskiTechnical Univ. of Varna, Bulgaria

Contents1. Background & Purposes2. Simulation Model3. Results4. Implosion Code5. Summary

No.2

Heavy Ion beam

Fuel pelletAccelerator

4~6m~mm

Problems

Background

*Beam Accelerator (Scale, Cost, etc..)*Physics of Intense Beam (Bunching, Emittance growth, etc..)*Beam Final Transport (Stable transportation, Interaction with gas, etc..)*Beam-Target Interaction*Analysis of Target-Plasma Hydrodynamics etc..

No.3

Purposes

Effective Implosion

MeV6.17nHeTD 10

42 ++⇒+

DTFuel pellet

Beam axis

Fuel pellet surface

HIB

Non-uniformity (< few %)

*Calculation of deposition energy on a fuel target*Development of 3D-implosion code

No.4

Simulation ModelDeposition energy from 1 Beam

Beam parameter

Void

Pb0.03mm

11.3g/cm3

Al0.97mm

2.69g/cm3

Void3.0mm

Pb+Al pellet structure

*Heavy ion beam: Pb+

*Particle energy: 8GeV*Beam temperature: 100MeV*Transverse beam emittance: 5.0 mm mard*Beam number density: 1.3x1011 1/cc*Beam number: 12,20,32,60,92,120*Beam distribution: Gaussian

No.5

HIB transverse emittance

TargetFocal Spot

αdvr

Ren

Rch f

RbeamBackward focal position

Forward focal position

fmin

fmax

Rf

RpInclude the Emittance Effect by changing the Focal Spot

No.6

Non-uniformity

∑=rn

iiiwσσRMS

( )

φθ

θ φ

σnn

EE

E

n

j

n

kijki

iRMSi

∑∑ −=

2

1

EE

w ii =

σrms:root mean square(RMS) non-uniformityσi:non-uniformity at a surface

<Ei>:mean deposition energy at a surfaceEijk:deposition energy at each point

nr,nθ,nφ:each mesh numberE:total deposition energyEi:total deposition energy at a surface

wi:weight function include the Bragg peak effect

Energy distribution at the target surface (120-beam)

No.7

Simulation Results@Bragg peak layer

Reduction of Other Mode1

10

20

Moden10

20

m

00.00050.001

0.00150.002

0.0025Amplitude Sn

m

32-beam system

Dep

ositi

on e

nerg

y [r

el.u

nit]

RM

S no

n-un

iform

ity [%

]

%86.1rms =σ

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

3.3 3.4 3.5 3.6 3.7 3.8 3.9 40246810121416182022

Deposition energy[rel.unit]

Non-uniformity[%

]

Pellet radius[mm]

Dep. energy

RMS

PTV

Global

1

10

20

Moden10

20

m

00.00050.001

0.00150.002

0.0025Amplitude Sn

m

No.8

Effect of HIB Number

0

5

10

15

20

25

0 30 60 90 120 150

RM

S N

on-u

nifo

rmity

[%]

With beam temp.

Without beam temp.

2%

At least 32 beams are effective

No.9

Effect of Target Temperature

1

1.5

2

2.5

0 100 200 300 400 500

Target Temperature [eV]

RM

S N

on-u

nifo

rmity

[%] 120-Beam

60-Beam32-Beam

(a) Changes of stopping range (b) Target temperature v.s. RMS non-uniformity

DTFuel pellet

HIB illumination non-uniformity is kept low

during the HIB pulse duration

No.10

Fusion reactor

Displacement dz

Fuel pellet

Pellet entrance

Reactor chamber center

1

10

0.01 0.1dz [mm]

RM

S N

on-u

nifo

rmity

[%] 32-Beam

60-Beam120-Beam

(b) Rch=5m (a) Rch=2m

1

10

0.01 0.1dz [mm]

RM

S N

on-u

nifo

rmity

[%] 32-Beam

60-Beam120-Beam

Pellet Displacement

No.11

Reduce the Non-uniformity for the Pellet Displacement

xy

z -3

0

34

-4

-2-1

12

-30

3 4

-4-2 -1

1 2 -3

0

34

-4

-2-1

12

-3

0

34

-4

-2-1

12

-3

0

34

-4

-2-1

12

xy

z

-3

0

3

4

-4

-2-1

12

-30

3 4

-4-2 -1

1 2 -3

0

34

-4

-2-1

12

New scheme

32-HIBs

32-HIBs systemNew scheme&

Large radius

Large radius

Displace the HIB illumination point for the theta-direction (2 deg.)

No.12

Problems

Background2

*Beam Accelerator (Scale, Cost, etc..)*Physics of Intense Beam (Bunching, Emittance growth, etc..)*Beam Final Transport (Stable transportation, Interaction with gas, etc..)*Beam-Target Interaction*Analysis of Target-Plasma Hydrodynamicsetc..

Heavy Ion beam

Fuel pelletAccelerator

4~6m~mm

No.13

Initial ConditionIllumination Pattern

6

320

Power [TW]

Pulse [nsec]20 24 34

12-HIBs system

32-HIBs system

3.04mm

3.14mm

3.54mm3.57mm

VoidDT

Al

Pb

0.19g/cm3

2.69g/cm3

11.3g/cm3

No.14

Preliminary results

0 0.1 0.2 0.3 0.4 0.5

[keV]

0 500 1500 2500 3500

1

2

3

0

0 2x1012 6x1012 1x1013 1.4x1013 1.8x1013

[kg/m3]

[Pa]

1 2 3 4 5 [mm]

0 500 1500 2500 3500

0 0.1 0.2 0.3 0.4 0.5

1

2

3

0

0 2x1012 6x1012 1x1013 1.4x1013 1.8x1013

[kg/m3][keV]

[Pa]

1 2 3 4 5 [mm]

12-HIBs@32nsec

ion temp. density

pressure

ion temp. density

pressurePbAl

DT

PbAl

DT32-HIBs@32nsec

No.15

Initial Condition2

12-HIBs system

6

320

Power [TW]

Pulse [nsec]20 24 34

32-HIBs system

Illumination Pattern

3.00mm

3.13mm

3.97mm4.00mm

VoidDT

AlPb

0.19g/cm3

2.69g/cm3

11.3g/cm3

AlFoam3.20mm

3.70mm0.027g/cm3

2.69g/cm3

No.16

Preliminary results

0 0.05 0.1 0.15 0.2 0.25

1

2

3

0 2e+12 6e+12 1e+131.4e+13

0 500 1000 1500 2000 2500

0 1 2 3 4 5 6 7 [mm]

[keV]

[Pa]

[kg/m3]

0

0.1

0.2

0.3[keV]

1

2

3

0

1000

2000

3000

0 1 2 3 4 5 6 7 [mm]

0

4e+12

8e+12

1.2e+13[Pa]

[kg/m3]

12-HIBs@36nsec 32-HIBs@36nsec

ion temp. density

pressure

ion temp. density

pressurePb

DT

PbAl

DTAl

No.17

Summary

HIB illumination non-uniformity can be smoothed due to the beam temperature and emittance

HIB illumination non-uniformity is kept low during the HIB pulse duration onto a direct-driven pellet in ICF

The non-uniformity is reduced by changing the illumination pattern for the pellet displacement

In the case of the large non-uniformity (12-HIBs system), our implosion code works well

The implosion non-uniformity is suppressed by foam layer

Future Subject

Find a optimum parameters (HIB pulse, target structure, etc..) to effective implosion