Transcript Sample Presentation

Fusion Magic?
“Any sufficiently advanced technology is indistinguishable from
magic. Radical, transformative technologies typically appear
‘impossible’ when proposed, and obvious and inevitable once in
place. To see things in a different way from those before is a rare,
but necessary, quality in an innovator. Getting there from here takes
courage and determination in addition to intellect, and is often
driven by an underlying vision that transcends rationality.”
A.C. Clarke, “ Profiles of the Future: An Inquiry into the Limits of the Possible” Holt,
Rinehart and Winston, NY (1982).
Chamber Studies
Wayne Meier
Lawrence Livermore National Lab
Laser IFE Program Workshop
Naval Research Laboratory
February 6 & 7, 2001
* This work was performed under the auspices of the U.S. Department of Energy by the University of California,
Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.
Chamber studies area includes several tasks
• Target emissions (x-rays, debris, neutrons) for direct and
indirect drive targets will be characterized
• Alternate chamber concepts will be developed and analyzed
– System integration/interface issues identified
– Analyses & experiments proposed to address critical issues
• Systems models will be improved and used to evaluate plants
for KrF and DPSSLs
• Neutron damage modeling of chamber walls will be supported
Chamber studies will benefit both DP and IFE
• Threats to the chambers are similar but to varying degrees
• Damage mitigation techniques will be required by both DP and IFE
chambers
• Analytical tools have commonality
– Target physics and characterization of target emissions
– Wall ablation calculations
– Chamber dynamics (condensation, impulse to structures)
– Neutron transport, activation, and damage modeling
• Systems integration considerations are important
– Design constraints (e.g., rep-rate limitations)
– Subsystem interface issues
• Systems modeling and optimization will help guide R&D
– Goals and metrics for various applications
LLNL Chamber Studies
Overall Objective…………..
Integrated laser IFE chamber concepts
FY 01 Deliverables………...
1. Progress report on alternate chamber
concept(s) including proposed next steps
2. Status report on systems modeling for laser
IFE (models and resulting analyses)
PI Experience………………. Fusion Technology Group Leader (LLNL)
(POC: W. Meier)
Past project manager for Sombrero/Osiris power
plant study
Proposed Amount………….. $ 700k
Relevance of Deliverables
[ ] NIF……………………
[X] Laser RR Facility…. Chambers for high rep-rate applications
[X] Other DP/NNSA…… First wall protection options
[X] Energy……………… Options for attractive chamber/plant designs
Related OFES activities…… Other chamber technology and systems studies
including ARIES-IFE
Chamber first wall damage and survival is a
key issue for both DP and IFE chambers
• Possible chamber wall threats
– Laser light
– X-rays
– Shrapnel (high velocity, solid and liquid projectiles)
– Debris (vaporized target material and fusion burn products)
– Gamma rays
– Neutrons
• Tasks include
– Characterizing target emissions for different types of targets
– Developing/improving first wall protection concepts
Example target spectra
Particles per unit energy (#/keV)
Burn Product Spectra from the NRL Target 1-D Analysis
10
17
n
He4
T
10
15
H
10
D
13
He3
10
11
g
10
9
10
100
1000
Particle energy (keV)
L.J. Perkin et al., ARIES Meeting, PPPL, Sept. 19, 2000
10
4
Alternate chamber concepts - FY01 plan
• Review literature
• Identify potentially promising chamber concepts for direct drive
– Magnetically protected
– Wetted wall
– Alternate first wall materials/coatings
– ?
• Select concept(s) for additional study
• Complete preliminary analysis/assessment to identify key issues
• Propose next steps (analyses, simulations, experiments?) needed
to resolve issues
• Complete progress report
One possible example – Magnetically
protected first wall
I.O. Bohachevski et al., Nuclear Technology/Fusion, 1, 390 (1981)
Does MHD conversion make any sense?
B. G. Logan, Fusion Engineering and Design, 22, 151 (1993).
Systems integration is an important aspect
of the proposed work
• It is important not to develop subsystems in isolation –
encourage interactions of individuals working on target physics,
chambers, target fabrication and injection
• Interface issues and constraints often require design trade-offs
• Laser/target/chamber interface issues will be considered for
chamber design concepts we analyze
Final optics configuration depends on
target type and chamber design
3D neutronics model of SOMBRERO target
building including final optics and neutron dumps
•
•
•
•
•
60 beams
Uniform (direct-drive) illumination
Dry-wall chamber
Fused silica final optics (wedges)
Focusing mirrors removed from
direct line of site
Systems models and analyses will help identify
the optimum design configurations
• Models include systems performance and cost as a function of
design variables for laser, chamber, support and/or plant
facilities
• Used to optimize various figures of merit
– Shot rate
– Laser efficiency
– Project cost
– Cost of electricity (IFE)
• Used to identify design aspects with high leverage for concept/
design improvements
Yield / rep-rate operating space – an example
1000
Limit on max yield, e.g.,
set by first wall limits for
given wall design and
radius
Target Yield, MJ
800
600
400
Limit on max rep-rate,
e.g., set by chamber clearing
or target injection velocity
200
0
0
2
4
6
8
10
12
14
16
R ep-rat e, H z
Low alpha, zooming, eta = 15%
Alpha = 3, eta = 5%
As chamber radius increases, the max yield typically increases,
but max rep-rate might decrease (longer clearing time, limited
target transit time). Constraints would shift up and left.
Rep-rate constraints could prevent operating
at minimum COE point
COE (c/kWeh) and Rep-rate (Hz)
2
5 Hz pt.
E = 4.4 MJ
1.5
E
(MJ)
2.4
3.1
4.7
1
Min COE pt.
E = 2.4 MJ
0.5
0
0
1
10 Hz pt.
E = 3.1 MJ
2
3
Driver Energy, MJ
COE for alpha = 2
Rep-rate for alpha = 2
4
5
RR
(Hz)
15
10
5
COE
(norm.)
1.00
1.01
1.11
Neutron damage modeling work will be supported
• $100k will be provided to leverage off the large DP effort on
materials modeling for stockpile stewardship
• Need to include consideration of
– Fusion spectrum
– Fusion materials
The effect of pulsed irradiation can be
studied with kMC simulations
- We simulate pulse rates of 1 Hz, 10 Hz and 100 Hz and an instantaneous
dose rate of 1.4 dpa/s during the pulse (1s long).
- Simulations were carried out at 300K (Stage III -> mobile vacancies)
and 620K (Stage V->unstable vacancy clusters)
Pulsed irradiation
300 nm
Concentration of Traps
300 nm
Comparison between pulsed and
continuum irradiation in Cu at 300 K
4
Vacancy cluster size (cluster > 1)
3.5
3
The variable that controls vacancy
cluster size is the annealing time
between pulses, or between cascades in
the continuous irradiation case.
2.5
2
1 Hz
10 Hz
100 Hz
1.4 10-6 dpa/s
1.5
1
0.5
0
-5
-4
5 10
1 10
-4
-4
1.5 10
2 10
Dose (dpa)
Vacancy cluster density in iron irradiated at 300K
17
17
2 10
cluster density (cm
-3
)
2.5 10
If we compare pulsed irradiation with
continuous irradiation at 1.4 dpa/s
with fusion neutrons (Magnetic Fusion
conditions), the damage
accumulation is almost identical to the 1
Hz case, whose integrated dose
rate is also 1.4 dpa/s
1 Hz
10 Hz
100 Hz
1.4 e-6 dpa/s
17
1.5 10
17
1 10
5 1016
0
5 10-5
1 10-4
Dose (dpa)
1.5 10-4
2 10-4
Chamber studies area includes several tasks
• Target emissions (x-rays, debris, neutrons) for direct and
indirect drive targets will be characterized
• Alternate chamber concepts will be developed and analyzed
– System integration/interface issues identified
– Analyses & experiments proposed to address critical issues
• Systems models will be improved and used to evaluate plants
for KrF and DPSSLs
• Neutron damage modeling of chamber walls will be supported
We are looking forward to contributing in many areas
and working with this team to advance the technical
feasibility and attractiveness of laser IFE designs.