A New Twist to IFE - Impact Ignition -

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A New Twist to IFE- Impact Ignition -
M. Murakami Institute of Laser Engineering,
Osaka University
In collaboration with H. Nagatomo,1 K.
Nishihara,1 H. Shiraga,1 H. Azechi,1 Y. Izawa,1
F. Ogando,2 P. Velarde,2 M. Perlado,2 and S.
Eliezer3
Contents of talk What is Impact Ignition!? Gain
model Design window 2D hydrodynamic
simulation Cone shell experiments
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New Scheme Impact Ignition - Target Structure
and Flow Diagram -
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Advantages of Impact Ignition

1. Simple Physics

(2) High Efficiency
(3) High Robustness
(4) High Gain
(5) Low Cost
(6) No need for PW Laser
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Gain Model
Implosion velocity
Laser energy for igniter
Laser energy for compression
Total driver energy
Burn fraction
Energy gain
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Gain curves for Impact Ignition Targets
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Impact Ignition can be designed in other
illumination schemes
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Non-uniform implosion can achieve higher rR
values.
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Efficiently compressed core can be generated even
by nonuniform implosion
Cone shell target
X-ray image of the compressed fuel plasma
Those experimental results have been published
in Nature (2001 2003).
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Implosion experiment of cone-shell target at LLE
OMEGA laser
200 mm x 200 mm
CH shell1000 mmf, 25 mmt, D2 5
atm
Laser 35 beams 15 kJ/1 ns SQ (8x1014W/cm2 )
70deg Au cone
core
cone
X-ray emission from core and cone tip Ultrafast
x-ray image (Dt10 ps) obtained with MIXS
Multi-Imaging X-ray Streak Camera with PJX at LLE
by H. Shiraga, S. Fujioka, P. Jaanimagi, C.
Stoeckl, et al.
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Different irradiation schemes for indirectly
driven HIF- History of designs to kill low mode
asymmetries -But those are for spherical fuel
pellets!!
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Impact Ignition may allow us different beam
options beyond standard parameters.
I will talk a bit more details on this topic in
US-Japan Workshop after this symposium.
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2D Hydrodynamic Simulation
Isocontour map at a time shortly before the
impact
Isocontour map at peak comp- ression shortly
after the impact
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Hydrodynamic Efficiency
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Scaling laws for laser-driven ablation
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Design Window for Laser and Target Parameters
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High isentrope suppresses Rayleigh-Taylor
Instability
Under constant acceleration for
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Summary

• A totally new ignition scheme, Impact Ignition,
  has been proposed.
• Impact Ignition has very attractive features.
• Major breakthrouh expected in future experiments
  is to demonstrate high implosion velocities at
  low isentropes.

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Direct drive for the igniter shell has much
higher potential to achieve Impact Ignition than
indirect drive
Advantages

1. Laser pulse shape and irradiation timing can be
   rather freely designed.
2. With high specific deposition power, the exhaust
   velocity and thus the implosion velocity is quite
   controllable.
3. Experiment can be conducted under orthodox laser
   systems (Gekko XII) with no special know-how for
   the target fabrication and optical design and
   operation.

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In indirect scheme, it is hard to achieve high
implosion velocities for the ignitor shell