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October 19, 2003 Fusion Power Associates
Status of Fast Ignition-High Energy Density Physics
Joe Kilkenny
Director Inertial Fusion TechnologyGeneral Atomics
San Diego, California
Ignition and gain curves for multiple target concepts show the advantages of Fast Ignition
— Fast ignition potentially gives more gain and lower threshold energy then “Hot Spot” ICF but the science and technology are far less developed
FI at NIF
T ρ
Shock heated central spot ignites - a high density cold shell
~ Pc = αρc5/3~
Conventional ICF
Intensity ~1014 - 1015 w/cm2
Fastinjectionof heat
T
r
ρ
-Fast e– heated side spot ignites , a lower density larger uniform
>> fuel ball Pc =
Fast Ignitor
Intensity ~1020 w/cm2
Indirect Drive
Advanced Indirect
Drive on NIF
Fast Ignition has attractive features in addition to high gain at lower total drive energy
• Challenging science and technology• Compression MIGHT be possible with all Drivers
0.53 m , 1.05m (?)• Brightness requirements for compression drivers are reduced
– Radiation temperatures of ~100ev required for compression!• Direct and Indirect target schemes for compression• Innovative target concepts
– one-sided indirect drive– indirect drive illumination ( PDD) for direct drive– asymmetric compression drive configurations
• Target fabrication tolerances are relaxed
NIF produces ~4 MJ at 1.05 m
Heavy Ion Beam Drive
Z-pinch DriveIndirect Laser drive
Direct Laser driveHeavy Ion Beam Drive
ions
Fast Ignition is compatible with all drivers
Innovative target designs are possible
BUTIgnitor laser energy
must be determined!
NNSA is interested too! The photons, electrons and ions from PW lasers can be used to heat and diagnose HEDP plasmas
Multi-kJ PW’s are now planned for OMEGA(EP), Z-R, and NIF
The Z-Beamlet laser is being upgraded to provide a high energy PW laser for use on Sandia’s Z facility
Z-Beamlet multikilojoule laser facility
Z-Beamlet and Z-PW laser
facility
Z z-pinch facility
Z multimegajoule z-pinch facility
• The Z-Beamlet laser will provide a 2-4 kJ, 1-10 psec laser ~ 2007
• A 50-200 J, 0.5 - 10 psec prototype laser system will begin operation in 2004.
High energy radiography and fast ignitor experiments on Z facility
Resistive inhibition needs testing under ignition relevant conditions
Experiments are needed in low resistivity plasmas
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
0.1 1 10 100 1000
Temperature eV
Resis
tivit
y O
hm
m
Current expts
DT fuel
Au cone ??
Ohmic limit in FI
CD1 g/cc
D2
10 g/cc
100 g/cc
Au
CD
Critical Surface
Dense Gold
Coronal Plasma/Gold
Compressed Core
e
US OFES effort addresses all aspects of FI
• OFES support is highly leveraged– Complementary programs– Internal funds – Overseas collaborations
• FI Target design efforts at NNSA funded labs
– SNL - Z - PW– LLE - Omega EP– LLNL - NIF -HEPW
US Fusion Energy program OFES
UC Davis
Princeton
GA
Vulcan
GekkoXII
LULI
LLNL
LLE
SNL
UN,Reno
Ignition target design
Fast Ignition Concept Exploration
OMEGA
Hydro Modeling agrees very well
• Stagnation time, shape
• Compressed density
• Emission from target
• Model does not include mixing of Au vapor with collapsing shell - will measure from excess self-emission
Models may be sufficiently accurately to for target design extrapolations
• Compact mass, ~60 mg/cm2
minimal cone vapor
Electron beam is moderately well directed
Al thickness micron
2500 5000 7500 10000 125000905xray03
180 m
Cu
20m
Al
20 m
0
100
200
300
400
500
600
0 100 200 300 400 500
Al thickness, µm
Spot diameter, µm
LULI data (20 J, 0.5 ps)
RAL data (100J, 0.8 ps)
• Minimum spot size 70 m, cone angle 40°
• Insensitive to pulse energy (to 100 J)
GEKKO laser: 12 green laser beamsE= 10 kJ, t = 1-2 nsec.Uniform irradiation(phase plates) for high density compression.I ~1014 watts/cm2
PW laser: 1 beam (~400 J)At 1 micron.PW peak power is utilized for fast heating.I~1019 watts/cm2
ILE Osaka
Integral FI experiments at Gekko XII-PW have catalyzed FI interest worldwide
Integral experiments at ILE show efficient heating
• Nine drive beams, 2.5 kJ• 1/2 PW ignition beam• Deuterated plastic target
300 J short pulse doubled the core plasma temp to 0.8 keV implying 40% coupling of EPW
250m
X-ray image
Cone Target
104
106
108
0.1 1
Neu
tro
n Y
ield
Heating Laser Power (PW)
c
Rqd timing ~50ps
0
100
200
-200 -100 0 100 200Injection Timing (ps)
0
10
5
a
2.25 2.35 2.45 2.55 2.65
Energy [MeV]
0
1.0
0.5
b
T~0.8 keV
ILE Osaka
A credible pathway to take FI to concept demonstration exists
• Proof of Principle (Concept Extension) Significant core heating at relevant conditions– FIREX1 (Japan)
• Concept Demonstration (Ignition/gain)– US Facilities (, Z, NIF)
with PW
Summary
• Short pulse ( < ~10 psec), high brightness lasers (B > 1015
Watts/cm2-st) have enabled the new field of “high energy density physics (HEDP)”
• There is an increasing national and international interest in HEDP• Fast Ignition exploits the physics and technology of HEDP
& features:– Science frontier-relativistic plasmas, etc– Compatible with all drivers– Flexibility in reactor concepts– International collaborations ?– High gain potential at sub-megajoule energies