Development of multidimensional Monte Carlo simulation code for H− ion and neutral transport in H− ion sources

Abstract

Two multidimensional Monte Carlo simulation codes—(a) neutral (H2,H) transport code and (b) negative ion (H−) transport code—have been developed. This article focuses on the recent simulation results by the neutral transport code for the H− production in a large, hybrid negative ion source, “Camembert III.” Two-dimensional spatial profiles of vibrationally excited molecules H2(v) and H− production are obtained for a given background plasma profile. Both H2(v) and H− ions are mainly produced near the filaments in the driver region. However, the H− source density has double peak in its spatial structure, while the density profile of H2(v) is characterized by the “mushroom” structure with a single peak. These results indicate a large potential of the neutral transport code, not only for the understanding of underlying physics, but also for designing ion sources, including complicating effects of geometry, spatial and velocity distribution of particles, and atomic and wall processes.