Fast Ignition separates the lasers for

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Fast Ignition separates the lasers for Implosion
and Heating.
ILE Osaka
Implosion
Heating
Ignition Burn
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Fast ignition is predicted to have high gain
with compact laser system.
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Fast Ignition requires to deliver ultra-intense
heating pulse close to the core.
ILE Osaka
K. Fujita, K. A. Tanaka et al., SPIE 4424,
37(2001) Two 100 psec pulses were used to heat
the core at 100J.
Heating pulse(1-10 psec)
Hole Boring Pulse (100 psec)
Corona plasma
High density core
Heating hole boring pulse(1-10 psec)
Y. Kitagawa, K. A. Tanaka et al., submitted to
PRL (2004).) PW laser was used to heat the core
at 200J/0.5 psec.
Time
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ILE, Osaka has unique capability to conduct Fast
Ignition model exp.
GEKKO laser 12 green laser beams E 5 kJ, t
1-2 nsec. Uniform irradiation for high density
compression.
PW laser 1 beam At 1 micron. PW peak power is
utilized for fast heating.
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Electron Energy Transport Spectral Details
ILE Osaka
Hot electron temperature scales with
I1/2. Electrons flux is shown to be a single
filament toward the higher laser
energy. Coherent transition radiation can tell
us about the hot electron spectrum inside the
target.
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Hot electron temperatures appear to be higher
than simple JxB heating.
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Coherent transition radiation (CTR) comes from
hot electrons crossing the rear surface of
target.
ILE Osaka
Electron spectrometer does not monitor hot
electrons inside target. We have used CTR to
estimate hot electron characteristics.
Coherent transition radiation
Bunching electron beams with frequency wL,
2wL,...
Coherent transition radiation
Ultra-intense laser (wL)
J. Zheng, K.A Tanaka et al., PRL92, 165001-1
(2004).
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Electron temperature can be inferred from
coherent transition radiation.
ILE Osaka

• Fitting our theory on the data, the hot electron
  temperatures are 1.3 MeV and 5.5 MeV, inferring
  two temperatures in the target.

1.3 MeV
5.5 MeV
PRL92, 165001-1 (2004).
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Fsdy Ignition Experiments of Cone-Guide Heating
on Imploded High Density Core
PW for heating 1 beam / 300 J 1.053 mm / 0.5ps
GXII for implosion 9 beams / 2.5 kJ/0.53
mm 1.2ns Flat Top w/ RPP
Au cone 30 o open angle (the picture
60deg) Thickness of the cone top 5mm Distance of
the cone top 50mm from the center
CD shell 500mmf/6-7mmt
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Laser Conditions for Enforced Heating with
Peta-watt Laser System
Experimental Conditions Implosion Laser E
2.5 kJ, l 532 nm, t 1.2 nsec (flat top), 9
beams Enforced Heating Laser E 300 J, l
1053 nm, t 0.5 psec , 1 beam IL 1019 W/cm2
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Time of flight of neutron shows 800-1000 eV
temperature.
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Neutron increase is 1000 times with fast heating.
Short
Enforced heating is demonstrated at a heating
power almost equivalent to the ignition
condition.
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Hot spot appears to flow out toward the cone tip.
ILE Osaka
CH shell1000 mmf ???mmt, D2 0, 5 atm
10 psec. X-ray frame Image (MIXS)
Laser 35 beams 15 kJ/1 ns SQ (8x1015W/cm2 )
70deg Au cone
Plasma streams out of hot spot.
Shiraga/Fujioka/Tanaka/Kodama
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Gold cone-guided implosion achieves higher rR.
ILE Osaka
In Au cone guided case, the shell continued to
implode since the hot spot streams out. The
average rR reaches the value becomes 40 larger
than that for the spherical implosion.