| Paper | Title | Page |
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| WEP159 | Improved Algorithms for Multipacting Simulation in the Analyst Code | 1785 |
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Funding: Work funded by the U.S. Dept. of Energy, Office of Science, SBIR Contract No. DE-FG02-05ER84373. Electron multipacting is often deleterious in RF structures and must be controlled via modifications to the geometry, materials, or external fields. Recent improvements to the capabilities for modeling multipacting in the Analyst software package are presented in this paper. A backward difference scheme*, coupled with Newton-Raphson iteration, is used to integrate particle position/momentum, with integrations interrupted at element faces to minimize errors and lost particles. Support for the Furman-Pivi secondary emission model** has been implemented, with separate representations for low energy, re-diffused, and backscattered secondary particles, and multiple emissions per impact based upon a probability distribution. We have also developed a method to prune the tree of secondary particles resulting from an impact that minimizes particle count growth while maintaining important statistical information about the resonance. Finally, we have added support for volumetric sourcing of primaries, wherein the model volume is seeded with a population of particles with random positions and initial velocities. These improvements, along with benchmark calculations, will be presented. * D. Darmofal, et al., Jour. Comp. Phys., 123, 1996, pp. 182-195. ** M. Furman, et al., LBNL-52807, June, 2003. |
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