R' BETTI, C' ZHOU

1
HIGH DENSITY AND HIGH ?R FUEL ASSEMBLY FOR FAST
IGNITION
R. BETTI, C. ZHOU Fusion Science Center for
Extreme States of Matter and Fast Ignition
Physics Laboratory for Laser Energetics,
University of Rochester 32nd EPS Meeting, June
29 2005, Tarragona, Spain
2
Ignition with Fast Ignition requires a fuel
assembly with densities 500gt?sgt 300g/cc, ?s
?sgt0.4g/cm2 and small hot spot volume
500gt ?sgt 300g/cc
?s
Rh
?s
1MeV e-stopping ? s ?s gt0.4g/cm2
r
? s ?sgt0.4 g/cm2
Atzeni S, Phys. Plasmas 6, 3316 (1999)
3
Fusion energy with Fast Ignition requires ?s gt
300g/cc, ?s ?s 3g/cm2, small hot spot volume
and Gains gt 100
Fraction burned ?
Hydro-efficiency ?
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.02
0.03
0.04
0.05
0.06
0.07
0.08
4
The areal density is weakly dependent on
velocity. It increases for lower adiabats and
greater energies
3
?s
2
1
1
2
3
5
The density is independent of energy. It
increases with the velocity and decreases with
the adiabat
?s
6
The relative hot-spot size increases with the
velocity
7
All the ingredients for designing the optimal
fuel assembly for IFE Fast-Ignition are now
available
?Low adiabats improve densities and areal
densities Minimum practical adiabat ? 0.7-
0.8
?
?
?
FI-IFE target EL750kJ, ?0.7, Vi1.7?107cm/s
8
A FI-IFE target has been designed for a 750kJ
laser driver
Energy
Imp. Vel.
?
CH
2µm
CH(DT)6
177µm
750kJ
1.7 107
0.7
479µm
DT ice
DT ice
DT gas
Peak Den.
Max.
ltMax. Den.gt
DT gas
657µm
550 g/cc
670 g/cc
2.9-3.1 g/cm2
9
The 750kJ capsule is driven by a Relaxation laser
pulse with a 22ns main pulse and a 150 contrast
ratio R. Betti et al, Phys. Plasmas 12, 042703
(2005)
prepulse
150
100
100
50
10
Power (TW)
0
0.1
0.2
1
0
10
20
Time (ns)
Can NIF assemble reactor relevant fuel for
FI-IFE? Indirect drive pulse is 18ns with a c.
ratio of 100
10
The 750kJ capsule yields a density gt300g/cc over
a ?Rgt2g/cm2 and a hot spot volume lt 10 of high
density volume
27.34ns
27.42ns
27.50ns
? (g/cc)
11
The volume with ?lt200g/cc is less than 5 by
working below the triple point
4
0
0
27.32ns
27.50ns
3
5
0
27.40ns
3
0
0
? (g/cc)
2
5
0
27.50ns
2
0
0
1
5
0
1
0
0
5
0
0
2
0
4
0
6
0
8
0
12
A 25kJ driver can assemble fuel for Fast
Ignition using low-adiabat implosions of thick
shells with a pulse compatible with the OMEGA
laser system
130?m foam target driven on ? 1
Energy
Rh/?s
Est. Gain
CH
2µm
CH(DT)6
40µm
1.5
25kJ
5-10
90µm
DT ice
DT ice
DT gas
DT gas
Imp. Vel.
Max. Den.
Max.
298µm
700 g/cc
0.8 g/cm2
2.6 107 cm/s
13
The 130?m, ? 1 Omega-compatible capsule yields a
density gt300g/cc over a ?Rgt0.4g/cm2 and a hot
spot volume lt 20 of total volume
7.24ns
7.24ns
7.26ns
7.26ns
? (g/cc)
7.27ns
7.27ns
14
The 130?m, ?1 capsule is driven by a Relaxation
laser pulse within the capabilities of the Omega
laser
2
4
2
2
2
0
Main pulse length 3.5ns Prepulse width
70ps Prepulse/Main 0.4 Main Contrast ratio
32 Pulse Energy 25kJ Peak Power 20TW
8
1
8
6
1
6
)
W
1
4
4
T
(
r
1
2
e
2
w
o
1
0
P
0
0
0
.
0
2
5
0
.
0
5
0
.
0
7
5
0
.
1
8
6
4
2
0
0
1
2
3
4
5
6
7
T
i
m
e
(
n
s
)
15
Significant progress has been made in the design
of the fuel assembly for Fast Ignition.

• An IFE relevant FI fuel assembly has been
  designed.
• It requires a 750kJ driver to produce a fuel
  assembly with
• ?R 3g/cm2
• 300lt ? lt500g/cc
• Hot-spot volume/ total volume 5-7
• Estimated gain 150-200 (if fast ignited)
• A 25kJ capsule can be assembled on the Omega
  laser to
• achieve
• ?R 0.8g/cm2 , 300lt ? lt500g/cc
• Hot-spot volume/ total volume 20
• Estimated gain 5-10 (if fast ignited)