John Sethian & Stephen Obenschain Plasma Physics Division Naval Research Laboratory

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 Obenschain Plasma Physics Division Naval Research Laboratory Washington, 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. • 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. 1) Fusion energy is a worthy goal World Marketed Energy Consumption, 1980-2030 Quadrillion 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!

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. Electricity or Hydrogen Generator Pellet factory Reaction chamber Array of Lasers Final optics 3) We believe direct drive with lasers can lead to an attractive power plant Spherical pellet

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 twomain issues: Hydro stability & laser-target coupling Can calculate with bench marked codes New class of target designs show way to lower demo cost Laser (most costly component) is modular Lowers development costs Simple spherical targets: “fuel” made by mass production Power plant studies shown concept economically attractive Separated components provides economical upgrades

10. 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 15th HAPL meeting Aug 8 & 9, 2006 General Atomics/UCSD (San Diego) • Government Labs • NRL • LLNL • SNL • LANL • ORNL • PPPL • SRNL • INEL • Industry • General Atomics • L3/PSD • Schafer Corp • SAIC • Commonwealth Tech • Coherent • Onyx • DEI • Voss Scientific • Universities • UCSD • Wisconsin • Georgia Tech • UCLA • U Rochester, LLE • UC Santa Barbara • UC Berkeley • UNC • Penn State Electro-optics • Northrup • Ultramet, Inc • Plasma Processes, Inc • PLEX Corporation • FTF Corporation • Research Scientific Inst • Optiswitch Technology • ESLI

11. 21.83 nsec "Picket" Pulse Shape 1000 100 10 1 Power (TW) t3 22.40 nsec t2 t1 0 10 20 time (nsec) GAIN = 160  NRL 2D computer simulations predict targetgains > 160. Need > 100 for a power plant Laser = 2.5 MJ Similar predictions made by:University of Rochester Lawrence Livermore National Laboratory

12. The HAPL program is developing two lasers: Diode Pumped Solid State Laser (DPPSL) Electron beam pumped Krypton Fluoride Laser (KrF) Mercury DPPSL Laser (LLNL) Electra KrF Laser (NRL) 55 J @ 1051 nm* 15 nsec pulse 10 Hz 100 k shots continuous @ 10 Hz * Recently demo 73% conversion at 2 300-700 J @ 248 nm 120 nsec pulse 1 - 5 Hz 25 k shots continuous at 2.5 Hz Predict 7% efficiency

13. Target fabrication progress Made foam capsules that meet all specifications Produced gas tight overcoats Demonstrated smooth Au-Pd layer foam shells Au/Pd layer CH+ Au/Pd layer 4 mm Foam Sector of Spherical Target Au/Pd coated shells General Atomics Schaffer LANL

14. We have a concept to "engage" the target.Key principles demonstrated in bench tests("engage"  tracking the target and steering the laser mirrors) Coincidence sensors Target Glint source Focusing mirrors Vacuum window Dichroic mirror Amplifier / multiplexer/ fast steering mirrors Target ASE Source Alignment Laser Cat’s eye retroreflector Target Injector Mirror steering test Grazing incidence mirror General Atomics UCSD Penn State A.E. Robson Wedged dichroic mirror

15. Experimental / computational tools to develop a chamber wall to resist the "threats" from the target Thermo-mechanical (ions & x-rays) Helium Retention Ions: RHEPP (SNL) IEC (Wisconsin) Laser: Dragonfire (UCSD) X-rays: XAPPER (LLNL) Van de Graff (UNC) Modeling HEROS Code (UCLA) Armor/substrate interface stress Plasma Arc Lamp (ORNL)

16. "Magnetic Intervention" offers a way to keep the ions off the wall • Ions “radially push” field outward, stopped stopped by magnetic pressure • Compressed field is resistively dissipated in first wall and blanket • 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 Toroidal Dump ~ 13.0 m A.E. Robson 5.5 m inn

17. 1979 NRL experiment showed principal of MI. Recent simulations predict plasma & ion motion 15 10 5 0 2D EMHD Simulation r (cm) NRL data 0 1 2 3 4 5 t (sec) NRL Voss Scientific (D. Rose) A.E. Robson *R. E. Pechacek, et al., Phys. Rev. Lett. 45, 256 (1980).

18. 3) We can lower the cost to “develop the concept” (aka ready to build full size power plants) James Watt’s Steam Engine

19. The key to lowering development cost: New class of target designs that produce substantial gain with lower laser energy NRL calculations gain = 60 @ 460 kJ LLNL calculations gain = 51 @ 480 kJ 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. Higher Gain: Higher implosion velocity Lower aspect ratio Yes No Laser plasma instability limits peak I2 P scales approximately as I7/9-2/9  PMAX scales as -16/9 Factor of (351/248)-16/9 = 1.85 advantage for KrF’s deeper UV over frequency-tripled Nd-glass Better stability Shorter wavelength of KrF:

21. The Fusion Test Facility (FTF) Laser energy:  500 kJ Rep-Rate  5 Hz Fusion power:  100-150 MW 28 kJ KrF laser Amp 1 of 22, (2 spares) Reaction Chamber Laser Beam Ducts

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. 5) We have proposed a three stage program a) Well-defined “go / stop” points b) Progressively more capable facilities Develop full-size components • Target physics validation • Calibrated 3D simulations • Hydro and LPI experiments • Nike enhanced performance, or NexStar, OMEGA, NIF, Z Stage I 2008-2013 • 25 kJ 5 Hz laser beam line • (first step is 1 kJ laser beam line) • Target fabrication /injection • Power plant & FTF design • 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 II 2014-2022 operating ~2019 Stage III 2023-2031 • Prototype Power Plants (PowerStars) • Power generation • Operating experience • Establish technical and economic viability

24. STAGE I is a single laser module of the FTFcoupled with a smaller target chamber Laser energy on target: 25 kJ Rep Rate: 5 Hz (but may allow for higher rep-rate bursts) Chamber radius 1.5 m Target Chamber Target ~28 kJ KrF Laser (1 of 20 final amps needed for FTF) 90 beamlets Target Injector Mirror • 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. • 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

27. The Vision…A plentiful, safe, clean energy source Working in 25 years or less A 100 ton (4200 Cu ft)COALhopper runs a 1 GWe Power Plant for 10 min Same hopper filled with IFE targets: runs a 1 GWe Power Plant for 7 years