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1
Fusion energy: How to realize it sooner and with
less risk.featuring as a case study:
The Laser Fusion Test Facility (FTF)
John Sethian & Stephen ObenschainPlasma Physics Division
Naval Research LaboratoryWashington, DC 20375
2
How should nuclear fusion fit in to the"nuclear renaissance?"
R&D Synergy
An opportunity to develop fusion on a much faster than “traditional” timescale
3
If nuclear fission is in it's Renaissance,
Then its time to get fusion out of the Dark Ages
4
A prescription to realize a practical fusion energy source within the next few decades
1) Fusion energy is a worthy goal---Don’t get distracted
2) Encourage competition & innovation.
3) Pick approaches (fusion concepts) that: a) Value simplicity b) Lead to an attractive power plant
(technically, economically, environmentally…) c) Require less investment to develop
4) Develop science & technology as an integrated system
5) Staged program with well defined “go / no-go” points Elements developed and incorporated into progressively
more capable facilities
5
World Marketed Energy Consumption, 1980-2030Quadrillion BTU
An energy source that features
• plentiful fuel, with no geopolitical boundaries
• minimal proliferation issues (if any)
• no greenhouse gasses
• tractable waste disposal
Would be of great economic, social, and political benefit!
1) Fusion energy is a worthy goal
6
Fusion is important and valuable enough to stand on its own right
usually the first approach defines the technology ................for better or worse
fusion has lots of advantages, let's not nullify them with distractions
7
2) "Competition improves the breed*"
* F.L. Porsche
8
Electricityor Hydrogen Generator
Reaction chamber
Spherical pellet
Pelletfactory
Arrayof
Lasers
Final optics
3) We believe direct drive with lasers can lead to an attractive power plant
9
Why we believe direct drive with lasers can lead to an attractive power plant
Target physics underpinnings developed under ICF program:(Omega, Z, Nike, and NIF)
Only two main issues: Hydro stability & laser-target couplingCan calculate with bench marked codes
New class of target designs show way to lower demo cost
Laser (most costly component) is modularLowers development costs
Simple spherical targets:“fuel” made by mass production
Power plant studies shown concept economically attractive
Separated components provides economical upgrades
10
Universities1. UCSD2. Wisconsin3. Georgia Tech4. UCLA5. U Rochester, LLE6. UC Santa Barbara7. UC Berkeley8. UNC9. Penn State Electro-optics
Government Labs1. NRL2. LLNL3. SNL4. LANL5. ORNL6. PPPL7. SRNL8. INEL
Industry
1. General Atomics2. L3/PSD3. Schafer Corp4. SAIC5. Commonwealth Tech6. Coherent7. Onyx8. DEI9. Voss Scientific
10. Northrup11. Ultramet, Inc12. Plasma Processes, Inc13. PLEX Corporation14. FTF Corporation15. Research Scientific
Inst16. Optiswitch Technology17. ESLI
15th HAPL meetingAug 8 & 9, 2006
General Atomics/UCSD(San Diego)
4) We are developing the Science & Technology for a laser fusion power plant as an integrated system. In other words: as if we plan to build one
11
NRL 2D computer simulations predict targetgains > 160. Need > 100 for a power plant
Laser = 2.5 MJ 21.83 nsec
22.40 nsec
GAIN = 160 Similar predictions made by:University of RochesterLawrence Livermore National Laboratory
"Picket" Pulse Shape
0 10 20time (nsec)
Power(TW)
1000
100
10
1
t1
t2
t3
12
The HAPL program is developing two lasers: Diode Pumped Solid State Laser (DPPSL) Electron beam pumped Krypton Fluoride Laser (KrF)
Electra KrF Laser (NRL) Mercury DPPSL Laser (LLNL)
300-700 J @ 248 nm120 nsec pulse1 - 5 Hz25 k shots continuous at 2.5 HzPredict 7% efficiency
55 J @ 1051 nm*15 nsec pulse10 Hz100 k shots continuous @ 10 Hz* Recently demo 73% conversion at 2
13
Target fabrication progress Made foam capsules that meet all specifications Produced gas tight overcoats Demonstrated smooth Au-Pd layer
DT Vapor
DT Ice (fuel)
Foam/DT (ablator)
CH
334m
256m
5 m
DT Vapor
DT Ice (fuel)
Foam/DT (ablator)
CH
334m
256m
5 m
Sector ofSpherical
Target
4 mm
foam shells
Au/Pd coated shells
General AtomicsSchafferLANL
Au/Pd layer
CH+ Au/Pd layer
Foam
14
We have a concept to "engage" the target.Key principles demonstrated in bench tests
("engage" tracking the target and steering the laser mirrors)
Target
Coincidence sensors
TargetInjector
TargetGlint
sourceDichroic mirror
Cat’s eyeretroreflector
Wedged dichroicmirror
Grazingincidencemirror
Vacuum window
Focusingmirrors
ASE Source
Alignment Laser
Amplifier / multiplexer/ fast steering mirrors
Mirror steering test
General AtomicsUCSDPenn StateA.E. Robson
15
Experimental / computational tools to develop a chamber wall to resist the "threats" from the target
Thermo-mechanical(ions & x-rays)
Armor/substrate interface stress
Helium Retention
Modeling
IEC (Wisconsin)
Laser: Dragonfire
(UCSD)
X-rays:XAPPER(LLNL)
Plasma Arc Lamp(ORNL)
Van de Graff (UNC)
Ions:RHEPP(SNL)
HEROS Code(UCLA)
16
200ns
300ns
100ns
400ns
500ns
526ns
200ns
300ns
100ns
400ns
500ns
526ns
"Magnetic Intervention" offers a way to keep the ions off the wall
1. Ions “radially push” field outward, stopped stopped by magnetic pressure
2. Compressed field is resistively dissipated in first wall and blanket
3. Ions, at reduced energy and power, escape from cusp and absorbed in dump
Coils (4 MA each ~ 1T)--form cusp magnetic field
Expansion of plasma in cusp field:2-D shell model
A.E. Robson
ToroidalDump
5.5 m~ 13.0 m
inn
17
1979 NRL experiment showed principal of MI. Recent simulations predict plasma & ion motion
NRLVoss Scientific (D. Rose)A.E. Robson*R. E. Pechacek, et al., Phys. Rev. Lett. 45, 256 (1980).
15
10
5
0
r (cm)
0 1 2 3 4 5t (sec)
NRL data
2D EMHDSimulation
18
3) We can lower the cost to “develop the concept” (aka ready to build full size power plants)
James Watt’sSteam Engine
19
The key to lowering development cost: New class of target designs that produce substantial gain with lower laser energy
NRL calculationsgain = 60 @ 460 kJ
LLNL calculationsgain = 51 @ 480 kJ
468 km/ sec
449
406
353
344 100
0
60
120
Gain
0.2 0.4 0.6 0 .8
Laser energy (MJ)
0
0 25 50 75 100 125 1501
10
10 2
10 3
Thanks to J. Perkins, LLNL
20
Basis for higher performance:Shorter wavelength KrF laser drive more resistant to hydro instability.Allows higher implosion velocity of low aspect ratio targets.
Laser plasma instability limits peak I2
P scales approximately as I7/9-2/9
PMAX scales as -16/9
Factor of (351/248)-16/9 = 1.85 advantage forKrF’s deeper UV over frequency-tripled Nd-glass
Higher Gain: Higher implosion velocity Lower aspect ratio
Better stability Shorter wavelength of KrF:
No Yes
21
The Fusion Test Facility (FTF)
Laser energy: 500 kJRep-Rate 5 HzFusion power: 100-150 MW
28 kJ KrF laser Amp1 of 22, (2 spares)
Laser Beam Ducts
ReactionChamber
22
Objectives of the FTF
Develop the key components, and demonstrate they work together with the required precision, repetition rate, and durability
Platform to evaluate and optimize pellet physics Develop materials and full scale chamber/blanket
components for a fusion power plant.
Provide operational experience and develop techniques for power plants.
23
Stage I 2008-2013
Target physics validation Calibrated 3D simulations Hydro and LPI experimentsNike enhanced performance, or NexStar, OMEGA, NIF, Z
Develop full-size components• 25 kJ 5 Hz laser beam line• (first step is 1 kJ laser beam line) • Target fabrication /injection • Power plant & FTF design
Stage II2014-2022
operating ~2019
Fusion Test Facility (FTF or PulseStar)
• 0.5 MJ laser-driven implosions @ 5 Hz • Pellet gains 60 • 150 MW of fusion thermal power• Target physics• Develop chamber materials & components.
Stage III 2023-2031
Prototype Power Plants (PowerStars)• Power generation• Operating experience• Establish technical and economic viability
5) We have proposed a three stage program a) Well-defined “go / stop” points b) Progressively more capable facilities
24
STAGE I is a single laser module of the FTFcoupled with a smaller target chamber
Laser energy on target: 25 kJRep Rate: 5 Hz (but may allow for higher rep-rate bursts)Chamber radius 1.5 m
~28 kJ KrF Laser(1 of 20 final ampsneeded for FTF)
Target Chamber
Target Injector
Target
Mirror
90 beamlets
• Develop and demonstrate full size beamline for FTF• Explore & demonstrate target physics underpinnings for the FTF
25
A prescription to realize a practical fusion energy source within the next few decades
1) Fusion energy is a worthy goal---Don’t get distracted
2) Encourage competition & innovation.
3) Pick approaches (fusion concepts) that: a) Value simplicity b) Lead to an attractive power plant
(technically, economically, environmentally…) c) Requires less investment to develop
4) Develop science & technology as an integrated system
5) Staged program with well defined “go / no-go” points Elements developed and incorporated into progressively
more capable facilities
26
27
The Vision…A plentiful, safe, clean energy source
A 100 ton (4200 Cu ft) COAL hopper runs a 1 GWe Power Plant for 10 min
Same hopper filled with IFE targets: runs a 1 GWe Power Plant for 7 years
Working in 25 years or less