Overview of Heavy-Ion Fusion Focus on computer simulation aspect*

1. Overview of Heavy-Ion FusionFocus on computer simulation aspect* Jean-Luc Vay (and many others from the) Heavy-Ion Fusion Virtual National Laboratory Lawrence Berkeley National Laboratory Computer Engineering Science seminar University of California at Berkeley May 4, 2004 *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley and Lawrence Livermore National Laboratories under Contract Numbers DE-AC03-76SF00098 and W-7405-Eng-48, and by the Princeton Plasma Physics Laboratory under Contract Number DE-AC02-76CH03073

2. The U.S. Heavy Ion Fusion Program - Participation Lawrence Berkeley National Laboratory MIT Lawrence Livermore National Laboratory Advanced Ceramics Princeton Plasma Physics Laboratory Allied Signal Naval Research Laboratory National Arnold Los Alamos National Laboratory Hitachi Sandia National Laboratory Mission Research University of Maryland Georgia Tech University of Missouri General Atomic Stanford Linear Accelerator Center MRTI Advanced Magnet Laboratory Idaho National Environmental and Engineering Lab University of California a. Berkeley b. Los Angeles c. San Diego Employees of LBNL, LLNL, and PPPL form the U.S. Virtual National Laboratory for Heavy Ion Fusion

3. Outline • Fusion energy • Principles, advantages/disadvantages • Basic requirements • Paths to fusion • Heavy Ion Inertial Fusion • The target • The chamber • The accelerator • The source • Modeling developments • New physics • New algorithms • Experiment/simulation interface • Data analysis • Conclusion

4. FUSION ENERGY

5. FUSION ENERGY: principles

6. Equivalence of mass and energy Example: if a 1 gram raisin was converted completely into energy E = 1 gram x c2 = (10-3kg) x (3.108 m/sec)2 = 9.1013 Joules ~ 10,000 tons of TNT! • Einstein’s equation • m = mass of particle • c = speed of light ~ 3.108 m/sec • huge amount of energy can be extracted from mass conversion.

7. Advantages of fusion • Virtually inexhaustible resources of fuel (water) • Clean (no CO2 emission, almost no radioactive waste) • Fusion reactors are inherently safe. They cannot explode or overheat. • Byproducts or fuel cannot be used to build weapons of mass destruction • The fuel is accessible worldwide Disadvantages of fusion • Complex, still at conceptual stage • Centralization of power sources

8. FUSION ENERGY: Basic requirements

9. Two fundamental forces at play • Holds • Holds

10. T T D D In order to fuse, the nuclei have to • overcome electrostatic barrier: go into the right direction: out In out out Slice view 3D view need energy (millions of degrees) need many events (many particles) Find these conditions in? Find these conditions in “PLASMAS”

11. States of matter

12. FUSION ENERGY: Paths

13. The different paths to fusion energy “God’s way” “Human ways” Tokamaks ITER Particle accelerators Lasers (NIF)

14. HEAVY ION INERTIAL FUSION

15. An Artist’s Conception of a Heavy Ion Fusion Power Plant • From the overall system, we identify several parts and study them separately using theory, experiments and computer simulations.

16. HEAVY ION INERTIAL FUSION: the target

17. For symmetric illumination, the target is enclosed into a capsule • Examples of capsule • Hydrodynamic simulation of target implosion and capsule expansion (Lasnex) “hybrid” “close coupled”

18. LASNEX is validated against Laser fusion experiments

19. HEAVY ION INERTIAL FUSION: the chamber

20. Inside the chamber (Lasnex simulation) (Tsunami simulation)

21. Cut-away view shows beam and target injection paths for an example thick-liquid chamber

22. 3-D BPIC simulation of beam propagating through Flibe beam ions Flibe ions electrons at 27.6 ns; 10 GeV, 210 AMU, 3.125 kA, 5x1013/cm3 BeF2 target

23. Does plasma neutralization really work? LSP simulations results for standard bismuth main pulse 1.2-mm waist is acceptable for distributed-radiator target

24. Final-Focus Scaled Experiment studied effect of neutralizing electrons (from a hot filament) on focal spot size Electrostatic quadrupole lenses for beam set-up Magnetic quadrupoles for final focusing Unneutralized beam Partially neutralized beam LSP particle-in-cell Intensity in focal plane 400µA, 160 keV, Cs+

25. HEAVY ION INERTIAL FUSION: the accelerator

26. Acceleration Transverse confinement (magnetic or electric) Principles of particle accelerator (SLAC)

27. Marx ESQ injector matching diagnostics diagnostics High Current Experiment (HCX) began operation January 11, 2002. 10 ES quads

28. 9.44 m 3.11 m 2.22 m 1.38 m 2.51 m K+ source end station diagnostics ESQ injector Matching section 10 ES quads High-Current Experiment (HCX): first transport experiment using a driver-scale heavy-ion beam • K+, 1 - 1.8 MeV, 0.2 - 0.6 A, 4 - 10 µs, 10 ES quads, 4 EM quads • HCX is to address four principal issues: • Aperture limits (“fill factor”)? • How maximum transportable current affected by misalignment, beam manipulations, and field nonlinearities? • beam halo? • effects of gas and stray electrons?

29. 3-D WARP simulation of HCX injector

30. HEAVY ION INERTIAL FUSION: the source

31. Two possible ion source approaches Use a large diameter but low current density single-aperture ion source. (traditional) Extract hundreds of mm-scale high current density beamlets, from a multiple-aperture ion source. (experimental) 4 mA/cm2 100 mA/cm2/beamlet

32. Expt WARP STS-500 investigating large-aperture diode dynamics Phase Space at End of Diode Risetime Experimental results Warp simulation

33. 7.5 X (mm) -7.5 0. 0.5 1.0 1.5 Z (m) Physics design of 119-beamlet merging experiment on STS500 is complete Current = 0.07 Amps, Final energy = 400 keV • RZ and transverse slice simulation used to understand parameter space and optimize design • 3D used for validation • Physics design with spherical plates completed; iterated with designer to ensure “buildability” Normalized emittance

34. Beamlets from Argon RF Plasma Source meet the required specifications Single Beamlet: ParametersResults Status • Current density 100 mA/cm2 (5 mA) met goal • Emittance Teff < 2 eV met goal • Charge states > 90% in Ar+ met goal • Energy spread < a few % beam suffers CX met goal RF Source: Multiple Beamlet: Image on Kapton:

35. Merging Beamlet fabrication is in progress Einzel Lens Test (STS-100) qualified high gradient insulator (up to 35 kV/cm). Full-gradient test (STS-500) vacuum gap voltage gradient (>100kV/cm) Soon

36. MODELING DEVELOPMENTS

37. Final Focus Source and injector Accelerator Our next-step vision Beam Science  Inertial Fusion Energy NOW NEXT STEP Brighter sources/ injector integrated beam experiment (IBX) Maximum <J >, BnTransport Beam neutralization ...to test source-to-target-integrated modeling Theory/simulations 3

38. 2 m 250 ns 1.7 MeV The IBX mission is to demonstrate integrated source-to-focus physics Injector Accelerator 40 m (10 MeV) 15 m 250  25 ns Ion: K+ (1 beamline) Total half-lattice periods: 148 Total length: 64 m 5 - 10 MeV Drift Compression 7m 25 ns Neutralization Final Focus

39. We will develop an integrated, detailed, and benchmarked source-to-target beam simulation capability

40. MODELING DEVELOPMENTS: new physics

41. Electron production missing in simulation of HCX Beam head hit the structure

42. Toward a self-consistent model of electron effects fb,wall WARP ion PIC, I/O, field solve  fbeam, F, geom. • Plan for self-consistent electron physics modules for WARP • Key: operational; implemented, testing;partially implemented;offline development Reflected ions gas module fb,wall penetration from walls ambient nb, vb ions fb,wall volumetric (ionization) electron source wall electron source charge exch. ioniz. F electron dynamics (full orbit; drift) sinks ne

43. WARP and electron cloud code POSINST merged • the code POSINST, specialized in the prediction of electron clouds in high energy physics accelerator, was merged with WARP • brings new capabilities and collaborations for study of electron clouds in heavy ion fusion and high energy density physics • SpecializedGUI page added to WARP GUI by UCB UG student • run POSINST • Read/plot output data

44. New large time-step electron mover reproduces the e-cloud calculation in < 1/25 time Large time-step interpolated • Full-orbit , t=.25/fce A major invention that should have application to many fields including MFE, astrophysics, near-space physics...

45. MODELING DEVELOPMENTS: new algorithms

46. End-to-end modeling of a Heavy Ion Fusion driver km mm m • challenging because length scales span a wide range: mm to km(s)

47. The Adaptive-Mesh-Refinement (AMR) method • addresses the issue of wide range of space scales • crosscutting example from CFD 3D AMR simulation of an explosion (microseconds after ignition) AMR concentrates the resolution around the edge which contains the most interesting scientific features.

48. AMR-PIC simulation of ion source Low res. Medium res. High res. Medium res. + AMR 4eNRMS(pmm.mrad) Particle-In-Cell + AMR applied to HCX source in axisymmetric (r,z) geometry The high res. result is recovered with medium res.+AMR around beam edges at 1/4 of comput. cost X (m) Z (m)

49. Collaboration HIF/CBP and ANAG (Phil Colella’s group) to provide AMR library of tools to Particle-In-Cell codes Example of WARP-Chombo injector field calculation

50. Moving mesh Adaptive mesh px 10-5 10-4 10-3 10-2 10-1 1 x Vlasov Models offer low noise, large dynamic range Solution of Vlasov equation on a grid in phase space Courtesy E. Sonnendrucker et al., IRMA, U. of Strasbourg with HIF-VNL