1

Fast Ignition Program in Japan “Progress of Fast Ignition Project; FIREX”

Fast Ignition Realization Experiment

FIREX

ILE became a National User’s Facility for High Energy Density science on 2006.4 Fusion , Laser Astrophysics, EUV, and so on are main projects

Laser Spectroscopy

NIFS, Okayama Univ.,

High Pressure EOS

AIST Tokyo Inst. Tech

Laser Acceleration, Terahertz

Coherent X-Ray

JAEA KPRI

Fusion ScienceNIFS, Kyoto Univ., Hiroshima Univ.

Gifu Univ., Tokyo Univ.,----

Planetary ScienceEhime Univ, Tokyo Univ.

Laser Astrophysics

National Astronomical Obs.Kyoto Univ.

Tokyo Univ.,NIFS, ---

High Energy Density Science

ILE Osaka UniversityNuclear Physics

Particle Physics

Okayama Univ.

Laser Astrophysics

US, UK. France, China----

International COE

New Science

Fast Ignition

US, UK, ----

Radiation &Beam Science

US, UK, Germany, Fr.China,--

Back ground and outline of this talk

•

•

4

4

NIF ignition

Plan of FIREX Project

104

106

108

0.1 1

Neu

tro

n Y

ield

Heating Laser Power (PW)

15%

Azechi,1990 Kodama, Nature 2002

FIREX project toward Fast Ignition

GE

KK

GEK

O I

'88-89

Nova

LLNL,USA

10

1021

1020

10

19

1018

106

107

108

109

Plasma Temperature (oK)

GEKKOMII

'85-86

Fast IgnitionQ=100

Q=1

OMEGA,’96

(LLE, USA)

FIREX-I

FIREX-II

NIF USA

2001,ILE

FIREX-I MilestonesF. Year Laser construction Milestones

• 22005 Completion of LFEX amplifier

• 22006.5 14.4kJ out-put energy

• 22006.9 Compressor 1) Cryogenic DD target implosion construction hydrodynamics exp.

2) Cryogenic foam shell cone target

fabrication

3) Completion of FI3 and cone

target design

• 22007.3 1 beam experiment D2 exp. ~2kJ input

• 22008.3 4 beam experiment D2 exp. ~10kJ input

• 22009 D2 5keV heating

• 22010 DT experiment aiming at Q=0.1

Implosion Laser; 5~10 kJ/2 GXII laserHeating laser; LFEX

12 spherical irradiation

Gekko XII (20kJ/1ns)

Petawatt laser (0.8kJ/0.8ps)

LFEX (10kJ/1~10ps)

Amplifier

Pulse Compressor

ImplosiomHigh Density

12 beam bundleirradiation

Radiation Hydro

Lab.Astro.High Pressure

Main Laser Facilities for Laser Fusion at ILE, Osaka

70m

Pellet factory

Laser Bay

Chamber II

Chamber I

LFEX laser present status

32.5 cm

ILE, Osaka

• µ

• µ

• 10µm•

•

For FIREX-I

20µm

1 5 µm

500µm

Fill tube

500µm

Model experiments;Target daimeter:2mm , fill tube diameter:100µm Foam density: 100mg/cc, working gas: H2

FIREX-I target design-I

2.29ns

2.30ns

2.40ns

2.41ns

Cone target position dependence of implosion and cone breakThe cone top breaking time is insensitive to cone top position.

100µm20µm

Gold cone

Density contour

Temperaturecontour

1032

4

1042

4

1052

4

Tem

pera

ture

(K)

3.02.52.01.51.00.50.0

Time (ns)

Rear-Surface Temperature

Exp. Sim. w/o. Auw/. Au

Rear surface temperature before the shock arrival

CH foam target(w/o D2)

•

•

•

•

simulation

AuCH

Laser

ILE OSAKA

Gold cone design; Cone angle dependencewith 2-D PIC simulations

Target

• Cone target with angle of 15, 30, 40 deg.

• Density of 100 Nc with buffer region at rear.

• Initial temperature of 10 keV

• Immobile Ions

Laser pulse

• Plane wave with intensity of 1.0*1020 w/cm2

• Spot size of 10µm (FWHM)

• Linearly polarized

Observation point

Electrons are accelerated at cone wing by incident and

reflected laser fields

Electron momentum distribution at t=100,140,180fs

15o

30o

60o

For 30-deg cone target, electrons are accelerated along the target surface (surface-

acceleration), and the reflected field accelerates electrons along the propagation direction

(ponderomotive acceleration).

For 45-degree cone target,

electrons are incident laser

direction, and reflected wave

direction.

Laser 201.36J/0.5ps (0.5PW)Target Al+SiO2 Plane S-pol. 84.5deg

Angular distribution has 20 30° width

around tangential direction.

High energy electrons are confined at cone tip

(Quasi static field energy density)/[(EL2+BL

2)/2]

after laser pulse

Temporal evolution of

electron energy stored in cone

(energy density)/Nc mc2

After laser pulse

0 100 200 300 400 500 600 700

0.0

0.1

0.2

0.3

0.4

Ele

ctro

n e

neg

y/L

aser

ener

gy

Time [fs]

25% is stored for a long time

Laser pulse

1. Cone angle dependence : absorption rate

49 (26)%4.0%16.9%40deg

55 (25)%3.6%18.0%30deg

52 (25)%2.2%21.5%15deg

Absorption rate(stored at tip)

Flux ratio 2 *Flux ratio 1*

Flux ratio 1 denotes ratio dydtSdydtS laserx, is observing area (10µm width)

Flux ratio 2 is for electrons with energy less than 2 MeV.

Fast ignition experiments(Nature,2002,ILE and UK)

are reproduced

0 1 2 3 4 5 6 7 8 9 100.2

0.4

0.6

0.8

1.0

1.2

1.4

(0

>10g/cc)

<Te>

<Ti>

Time [ps]

Whole region <Te> <Ti>

Note that delayed heating is very important for efficient heating

Summary

• Fast ignition researches in FIREX-I have beenprogressing. The one beam heating experiment will bein 2007 and full beam experiments will start in 2008.

• LFEX Laser construction is in final stage.• Foam cryogenic cone shell target has been fabricated.• Preheating level of a foam cryogenic D2 later is

controlled by adding a thin high Z layer.• Integrated simulation code of cone shell target was

developed. The simulation code is benchmarked byKodama Exp. (Nature ‘01) on compression andheating of cone shell target.

• The simulations indicate r = 0.2 g/cm2 and T=5keV,20% heating efficiency which mean Q=0.1 and Ny=1015.

ILE OSAKA