Effect of Coulomb collision between surface produced H- ions and H+ ions on H- extraction mechanism and beam optics in a Cs-seeded H- ion source by 3D particle in cell model

S. Nishioka, S. Abe, K. Miyamoto, A. Fukano, A. Hatayama

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5 Citations (Scopus)

Abstract

Recently, in Cs-seeded H- ion sources for fusion applications, the experiments have shown that the surface produced H- ions are mainly extracted from the bulk plasma region, that is, 1-2 cm inside from the beam aperture. The purpose of this paper is to clarify the extraction mechanism of the surface produced H- ions from the bulk plasma region in Cs-seeded H- ion sources for fusion applications by our 3-Dimensional Particle in Cell model for the vicinity of the beam aperture. In the present model, Coulomb collisions between surface produced H- ions and H+ ions (CC H--H+) are taken into account by the Binary Collision Model. By our model, the trajectories of extracted surface produced H- ions and beam profiles have been investigated for the case with and without CC H--H+. From the results of trajectories for extracted surface produced H- ions, it has been shown that the surface produced H- ions extracted from the bulk plasma region are drastically increased due to CC H--H+. Thus, our results have shown that the surface produced H- ions are extracted from the bulk plasma region due to Coulomb collision with H+ ions. Moreover, our results of the beam profiles have shown that CC H--H+ causes the increase in the beam convergence component. From these results, Coulomb collisions between surface produced H- ions and H+ ions are shown to be very important for the modeling of the extraction mechanism and for the beam optics in Cs-seeded H- ion sources for fusion applications.

Original languageEnglish
Article number063302
JournalJournal of Applied Physics
Volume123
Issue number6
DOIs
Publication statusPublished - 2018 Feb 14

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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