Estimation of the cusp loss width in negative-ion sources

A. Fukano, T. Mizuno, A. Hatayama, M. Ogasawara

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

To estimate loss width in the cusp magnetic field in multicusp negative-ion sources, diffusion of plasma across magnetic field is investigated analytically. The transport process of plasma depends on various plasma conditions. Diffusion coefficients are classified by degrees of plasma ionization. In weakly ionized plasma, where a case of electron-neutral particle collision is dominant as compared with electron-ion collision, there is a possibility that ambipolar diffusion or electron short circuit occurs in plasma. This strongly depends on the conditions of the plasma, the system length, and the wall material. On the other hand, in fully ionized plasma, only ambipolar diffusion occurs automatically due to momentum conservation of electron and ion. In not fully but strongly ionized plasma, plasma diffusion depends on electron-neutral particle collision, ion-neutral particle collision, and electron-ion collision. Being based on the classification of the diffusion coefficients, we derive expressions of loss widths for various plasma conditions.

Original languageEnglish
Article number03A524
JournalReview of Scientific Instruments
Volume77
Issue number3
DOIs
Publication statusPublished - 2006 Mar 1

ASJC Scopus subject areas

  • Instrumentation

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