Self-consistent Langevin simulation of Coulomb collisions in charged-particle beams

  • Authors:

  • Ji Qiang;Robert D. Ryne;Salman Habib

  • Affiliations:

  • LANSCE-1, LANSCE Division, MS H817, Los Alamos National Laboratory, Los Alamos, New Mexico;LANSCE-1, LANSCE Division, MS H817, Los Alamos National Laboratory, Los Alamos, New Mexico;T-8, Theoretical Division, MS B285, Los Alamos National Laboratory, Los Alamos, New Mexico

  • Venue:
  • Proceedings of the 2000 ACM/IEEE conference on Supercomputing
  • Year:
  • 2000

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Abstract

In many plasma physics and charged-particle beam dynamics problems, Coulomb collisions are modeled by a Fokker-Planck equation. In order to incorporate these collisions, we present a three-dimensional parallel Langevin simulation method using a Particle-In-Cell (PIC) approach implemented on high-performance parallel computers. We perform, for the first time, a fully self-consistent simulation, in which the friction and diffusion coefficients are computed from first principles. We employ a two-dimensional domain decomposition approach within a message passing programming paradigm along with dynamic load balancing. Object oriented programming is used to encapsulate details of the communication syntax as well as to enhance reusability and extensibility. Performance tests on the SGI Origin 2000, IBM SP RS/6000 and the Cray T3E-900 have demonstrated goodscalability. As a test example, we demonstrate the collisional relaxation to a final thermal equilibrium of a beam with an initially ansiotropic velocity distribution.