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Recent Progress of Fast-Ignition Project in Osaka University (FIREX) Shinsuke Fujioka, Institute of Laser Engineering, Osaka University 2010.3.11

Recent Progress of Fast-Ignition Project in Osaka University (FIREX) Recent Progress of Fast-Ignition Project in Osaka University (FIREX) Shinsuke Fujioka,

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Recent Progress of Fast-Ignition Project

in Osaka University (FIREX)

Shinsuke Fujioka,Institute of Laser Engineering, Osaka University2010.3.11

ContributorsS. Fujioka, H. Shiraga, N. Miyanaga, J. Kawanaka, K. Tsubakimoto, Y. Fujimoto, N. Morio, S. Matsuo, Y. Kawakami, K. Kawabata, H. Yamamoto, T. Jitsuno, Y. Nakata, K. Shigemori, T. Kawasaki, K. Sawai, H. Murakami, K. Ueda, S. Takamiya, Y. Kubota, N. Sarukura, T. Shimizu, K. Suzuki, S. Urushihara, H. Oku, K. Hashimoto, K. Torimoto, A. Fujita, H. Hasegawa, H. Fujita, Y. Kitamura, H. Matsuo, T. Sakamoto, T. Sezaki, S. Yanagida, M. Koga, O. Maegawa, K. Shimada, S. Okajima, M. Arai, K. Ishii, M. Hatori, H. Nakamura, T. Watari, H. Hosoda, Y. Arikawa, H. Kikuchi, T. Nagai, H. Nishimura, T. Ueda, S. Ohira, Y. Sakawa, K. Tanaka, H. Habara, S. Tanimoto, S. Hino, K. Shimada, K. Kida, T. Iwawaki, T. Norimatsu, M. Nakai, H. Homma, H. Hosokawa, M. Nagata, H. Kadota, K. Fujioka, H. Kaneyasu, Y. Suzuki, H. Nagatomo, T. Johzaki, M. Murakami, M. Murakami, K. Mima, H. AzechiOsaka University, Japan

A. SunaharaInstitute for Laser Technology, Japan

H. Sakagami, T. Ozaki, A. IwamotoNational Institute for Fusion Science, Japan

T. TaguchiSetsunan University, Japan

Y. NakaoKyusyu University, JapanM. KeyLawrence Livermore National Laboratory, USAP. A. NorreysCentral Laser Facility, UKJ. PasleyUniversity of York, UK

•   One beam of the high power PW laser (LFEX) carries < 6 x 1018 W/cm2 of the peak intensity , integrated fast-ignition experiment is in progress with the LFEX laser.

• Neutron yield was increased by a factor of 30 by the fast heating.

• Coupling efficiency between heating laser (LFEX) and fuel was low (< 5%), because the inside of cone is filled with preformed plasma generated by pedestal (~ 3 ns, > 1013 W/cm2) of the LFEX pulse.

• Another one beam of the LFEX will be in operation in FY2010. Next campaign of the integrated FI experiment will start on August.

Summary

The most important physics related to the fast-ignition should be clarified in the FIREX project until FY2011.

Compression and heating are separated in fast ignition scheme. ILE, Osaka

Compression Heating Ignition & Burning

Demo. in 1991@OSAKA, JP

To be demo. in 2011@LIVARMORE, USA

To be demo. in 2011@OSAKA, JP

Output from

amplifier

2x2

1x4

2x2

Beam transport optics(2F 1F)

Pulse compressor (1F)

Focusing optics (2F)

Sensor 3

Sensor 1

One beam of the LFEX laser is in operation. Another one beam will be in operation inFY2010. ILE, Osaka

Fast-ignition experiment, which was stopped since 2002, was restarted in 2009. ILE, Osaka

Jun, 2002 0.5 keV heating with PWL

Feb, 2004 Construction of LFEX laser was started

Mar, 2005 First light of LFEX laser

Feb, 2007 Output Energy 2.9 kJ/beam@Broadband was achieved

Feb, 2008 Target irradiation with compressed beam was started

Nov, 2008 Precision alignment of pulse compressor

Dec, 2008 Target irradiation with high-power beam was started

Feb, 2009 Irradiation of Fast Ignition (FI) target was started

Jun, 2009 Integrated FI experiment (5 ps, < 2 x 1018 W/cm2)

Sep, 2009 Integrated FI experiment (1 ps, < 6 x 1018 W/cm2)

Fuel capsule attached with a cone is compressed by GEKKO XII laser and heated by LFEX laser. ILE, Osaka

ShellDiameter 500 µmThickness 7 µmMaterial CD plasticConeAngle   45 deg.Material 7 µm goldTip size 30 µm

Compression LaserGEKKO-XII

Fusion Fuel Heating LaserLFEX

Beam# 12 beamsEnergy 280 J/beams (2.5 kJ total)Duration   1.5 ns (Flat top)Wavelength 527 nm

Beam# 1 beamEnergy 100 -800 JSpot size 40 µm Duration   1 or 5 psWavelength 1053 nm

GEKKO XII

LFEX laser RA 50

OS 75S

RA 50

OS 75S

DFM 75RA 50

OS 75S

DA 400S

SF 400S

DFM 75RA 50

OS 75S

DA 400S

SF 400S

DFM 75RA 50LFEX laser

OS 75S

OS 125S

DA 400S

SF 400S

DFM 75RA 50

DFM 1 25

LFEX laser

OS 75S

OS 125S

DA 400S

SF 400S

DFM 75RA 50

DFM 1 25

LFEX laser

OS 75S

OS 125S

DA 400S

SF 400S

DFM 75RA 50

DFM 1 25

One oscillator was used for GEKKO-XII and LFEX, which are synchronized with an accuracy of 20 ps. ILE, Osaka

Many aspects of fast-heating plasma were measured with diagnostic technique. ILE, Osaka

X-ray pinhole cameraviewing inside of cone

X-ray streak cameraImp./heating timing

Tim

e (n

s)

Space

Hard x-ray cameraidentifying reaction region

X-ray framing cameraimplosion plasma diag.

Neutron detectorDiagnostic of fusion reaction

-1000 -950 -900 -850 -800 -750

-20

-10

0

B C D FS

ign

al O

utp

ut

(V)

Time (ns)

100 1000104

105

106

1.2ps 4ps

Yn

LFEX energy* [J]

Neutron yield was increased by increasing in heating laser intensity by shortening pulse duration. ILE, Osaka

S. FujiokaN

eutr

on

yie

ld

Heating laser (LFEX) energy [J]

1 ps (< 6 x 1018 W/cm2)

5 ps (< 2 x 1018 W/cm2)

w/o heating 1 x 104

Neutron yield v.s. heating energy

LFEX(5 ps)

LFEX(1 ps)<5 % of coupling

PWL(0.6 ps)15 – 20% coupling eff.

Heating laser energy (J)

Ion

tem

per

atu

re

(keV

)

ILE, OsakaS. Fujioka

Coupling efficiency between heating laser and fuel is quite low compared to the PW experiment.

Relation between ion temperature and laser energy

Goal

Slope temperature of fast electrons is relatively high compared to that obtained in the PW experiment.

L1402

L1404

L1411

L1405

L1406

L1408

scaling obtained in PW experiment

Ponderomotive scaling

Scaling by Pukov(Assuming scale length L = 30 µm)

Laser intensity (a.u.)

Slo

pe

tem

per

atu

re o

f h

ot

elel

ctro

n (

MeV

)Hot electron temperature v.s. laser intensity

ILE, OsakaS. Fujioka

Electron acceleration may be occurred in a preformed plasma inside a cone.

Lo

g (

lase

r in

ten

sit

y)

Time

a few ps ( FWHM )

a few ns (FWHM)

1. main pulse~ 1019 W/cm2

2. pedestal> 1010 W/cm2

Laser pulse shape

pedestal >1010 W/cm2  →  forming pre-plasma in cone→   accelerating electrons in plasma→   increasing too hot electrons  →  reducing coupling

ILE, OsakaS. Fujioka

Does the ring-shape emission imply that the inside of the cone was filled with preformed plasma ? ILE, Osaka

X-ray pinhole cameraviewing inside of cone

Density scale length of a preformed plasma, observed by using side-on x-ray backlighting, is > 50 µm.

Backlighter  ~ 2.7keV

LFEX Laser

Au Plate20.9°

500 μm

1 n

s

X-ray streak camera

LFEX

ILE, OsakaS. Fujioka

LFEX Laser

w/plasma Backlight

-0.91 ns

-0.61 ns

-0.30 ns

2100 mm

105 mm

3 mm

Main Target

CHCl Backlighter

Laser:1 kJ/ns in 2w

Sphericalbent crystal

M = 20Monochromatic x rays : 2.7 keV X-ray

Framing

Camera

Time

Framing image

Crystal spec.   (SAINT-GOBAIN)  Material: Quartz ( 21-33 )

  Radius : 200 mm  Bragg angle : 83.01°  

  Photo energy : 2.7 keV (Vanadium - Hea)

Schematic of diagnostics

Monochromatic x-ray imaging technique is used to measure areal density of the compressed fuel. ILE, Osaka

S. Fujioka

Self-emission image was not superimposed on a shadow image obtained with monochromatic imager. ILE, Osaka

S. Fujioka

+ 200 ps

- 400 ps

Max. compression

1.0

0.8

0.6

0.4

0.2

0.0

MT

F

50403020100wavelength (m)

0.113 µm

400 500 600 700 800 900

400

450

500

550

600

650

700

750

col

row

0 20 40 60 80 100 120

_30829_back_rotate_txt_x

shadow image of mesh

MTF v.s. wavlength

Dec, 2008 Target irradiation with high-power beam started

Feb, 2009 Irradiation of Fast Ignition (FI) target started

Jun, 2009 FI integrated experiment with 1-beam LFEX

late 2009 Multi-beam compression and focusing

Beam combining

early 2010 FI integrated experiment with multi-beam LFEX

Test of various advanced target concepts

2011 Demonstration of ignition temperature with FI

Heating up to ignition temperature (5 keV) should be demonstrated until FY 2011. ILE, Osaka

•   One beam of the high power PW laser (LFEX) carries < 6 x 1018 W/cm2 of the peak intensity , integrated fast-ignition experiment is in progress with the LFEX laser.

• Neutron yield was increased by a factor of 30 by the fast heating.

• Coupling efficiency between heating laser (LFEX) and fuel was low (< 5%), because the inside of cone is filled with preformed plasma generated by pedestal (~ 3 ns, > 1013 W/cm2) of the LFEX pulse.

• Another one beam of the LFEX will be in operation in FY2010. Next campaign of the integrated FI experiment will start on August.

Summary

The most important physics related to the fast-ignition should be clarified in the FIREX project until FY2011.