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.