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. 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, 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! 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 Electricity or Hydrogen Generator Reaction chamber Spherical pellet Pellet factory Array of 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 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 Universities 1.UCSD 2.Wisconsin 3.Georgia Tech 4.UCLA 5.U Rochester, LLE 6.UC Santa Barbara 7.UC Berkeley 8.UNC 9.Penn State Electro-optics Government Labs 1.NRL 2.LLNL 3.SNL 4.LANL 5.ORNL 6.PPPL 7.SRNL 8.INEL Industry 1.General Atomics 2.L3/PSD 3.Schafer Corp 4.SAIC 5.Commonwealth Tech 6.Coherent 7.Onyx 8.DEI 9.Voss Scientific 10.Northrup 11.Ultramet, Inc 12.Plasma Processes, Inc 13.PLEX Corporation 14.FTF Corporation 15.Research Scientific Inst 16.Optiswitch Technology 17.ESLI 15 th HAPL meeting Aug 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 target gains > 160. Need > 100 for a power plant Laser = 2.5 MJ nsec nsec GAIN = 160 Similar predictions made by: University of Rochester Lawrence Livermore National Laboratory "Picket" Pulse Shape time (nsec) Power (TW) t1t1 t2t2 t3t3

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) nm 120 nsec pulse Hz 25 k shots continuous at 2.5 Hz Predict 7% efficiency nm* 15 nsec pulse 10 Hz 100 k shots 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 Sector of Spherical Target 4 mm foam shells Au/Pd coated shells General Atomics Schaffer LANL 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 Target Injector Target Glint source Dichroic mirror Cat’s eye retroreflector Wedged dichroic mirror Grazing incidence mirror Vacuum window Focusing mirrors ASE Source Alignment Laser Amplifier / multiplexer/ fast steering mirrors Mirror steering test General Atomics UCSD Penn State A.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 "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 Toroidal Dump 5.5 m ~ 13.0 m inn

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

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 = 460 kJ LLNL calculations gain = 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. Laser plasma instability limits peak I 2 P scales approximately as I 7/9 -2/9  P MAX scales as -16/9 Factor of (351/248) -16/9 = 1.85 advantage for KrF’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 kJ Rep-Rate  5 Hz Fusion power:  MW 28 kJ KrF laser Amp 1 of 22, (2 spares) Laser Beam Ducts Reaction Chamber

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 Target physics validation  Calibrated 3D simulations  Hydro and LPI experiments  Nike 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 II operating ~2019 Fusion Test Facility (FTF or PulseStar) 0.5 MJ laser-driven 5 Hz Pellet gains  60  150 MW of fusion thermal power Target physics Develop chamber materials & components. Stage III 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 FTF coupled with a smaller target chamber Laser energy on target: 25 kJ Rep Rate: 5 Hz (but may allow for higher rep-rate bursts) Chamber radius1.5 m ~28 kJ KrF Laser ( 1 of 20 final amps needed 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