Recent Numerical Advances for Beam-Driven HEDP Experiments S. A. Veitzer, P. H. Stoltz, J. R. Cary Tech-X Corporation J. J. Barnard Lawrence Livermore National Laboratory Fusion Energy Science Advisory Committee Subpanel Workshop on High Energy Density Laboratory Plasmas August 24 - 26, 2008 Washington, D. C. ----------- Funded by DOE SBIR Grant #DE-FG 02 -03 ER 83797 -----------
Ion Beams Can Drive Target Heating • An attractive approach for studying HED, WDM, and ICF, • with a potential for producing IFE Different attributes than laser-driven heating, yet some physics still relevant to ICF, etc. – Uniform heating of macroscopic target volumes – High repetition rate – Cost-effective • Theory and simulation are important components for • • driving experiments Collaborative research with the HIF Virtual National Laboratory Recent successes in modeling energy deposition, especially with respect to low energy beams Tech-X Corporation 2
Threefold goals for enhanced numerical modeling • Develop and implement accurate stopping power • • models at and below the Bragg peak Increase access to and ease-of-use of numerical models of beam-material interactions for the research community Validate stopping power models with established codes and experiments Tech-X Corporation 3
Low-energy beams require nuclear stopping power models • Stopping power has three components – Bound electronic (Brandt-Kitigawa) – Free electron (Peter & Meyer-ter-Vehn) – Nuclear (Semi-empirical, SRIM) • Compare with Classical Bethe-Bloch stopping Tech-X Corporation 4
Modern software design standards provides increased usability • Models are implemented in C in a standalone numerical library called Tx. Physics – open source and free to download for non-commercial use • Automated build system works on Linux, Mac, and • • Windows Many language bindings for inclusion in simulation packages, e. g. Python, Java Routines are currently interfaced to – – WARP (LBNL) HYDRA (LLNL) VORPAL, OOPIC Pro (Tech-X) Others • Additional physics, e. g. secondary electron emission, • impact ionization, field emission, sputtering, and radiation models Python-driven web 2. 0 interface Tech-X Corporation 5
Web and Python access to Tx. Physics physics models http: //txphysics. txcorp. com Tech-X Corporation 6
Web interface allows quick access to stopping powers without coding http: //txphysics. txcorp. com Tech-X Corporation 7
Researchers can plot or download tables, save and publish http: //txphysics. txcorp. com Tech-X Corporation 8
Dual pulse simulations show d. E/dx differences In collaboration with researchers at LLNL, we have interfaced Tx. Physics stopping power models with Hydra. Tech-X Corporation 9
Dual pulse simulations show d. E/dx differences Tech-X Corporation 10
Dual pulse simulations show d. E/dx differences Tech-X Corporation 11
Future Direction: Grazing Incidence Focusing of beams • Grazing collisions with solid density nozzles (hollow cones) can focus space charge dominated beams – Secondary electrons provide enhanced beam neutralization – Multiple reflections from cone surface may reduce the spot size in the focal plane • Experiments are needed to – Measure secondary electron yields for grazing incidence collisions for various materials (conductors and insulators) – Demonstrate focusing by grazing incidence deflections • Computational models are needed to – Drive target design and fabrication – Predicting accelerator performance Tech-X Corporation 12
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