Three Dimensional Simulation of Ion Beam Extraction from an ECR Ion Source

S.M. Elliott, O. Delferrière, J. Simkin, E.K. White

Accurate prediction of ECR ion extraction behavior is important for high current density operation and subsequent beam transport calculations. In this paper we review the combined electric and magnetic space charge beam simulation of ion beam formation from an ECR ion source with a multi-electrode extraction system. Included in the simulation is the influence of secondary charged particles generated by ion collisions in the residual gas on the space charge in the beam. The self-consistent space charge simulation uses a finite element method with mixed linear and quadratic elements, magnetic fields incorporating non-linear magnetic materials, a plasma free surface emission model, and the generation of secondary charged particles by sampling of the primary beam trajectories. This method is useful for predicting the ion beam behavior from the ECR ion source under conditions of varying current density, electrode potential, and background gas pressure, including the behavior of suppressed electron flow and the influence of magnetic fields.

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