[Table of Contents]

Plasma and Fusion Research

Volume 5, S2066 (2010)

Regular Articles

Role of Negative Potential Barrier Formed by Electrons Confined in the Stochastic Magnetic Region of Helical Nonneutral Plasmas
Haruhiko HIMURA, Mitsutaka ISOBE1), Akihiro SHIMIZU1) and Sadao MASAMUNE
Department of Electronics, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-0855, Japan
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
(Received 7 December 2009 / Accepted 9 March 2010 / Published 10 December 2010)


Nonneutral plasmas confined in the helical magnetic surface (HMS) region can be produced by injecting electrons from outside the last closed flux surface (LCFS). Recently, we numerically calculated outward electron orbits that extend to the inner HMS region. Once it penetrates the HMS region, the injected electron is never lost to the chamber wall, because the negative self-electric potential φs in the stochastic magnetic region (SMR) acts as a potential barrier. Remarkably, during the reflection process at the potential barrier, the electron is still trapped in the foot of the negative φs region, although it completely overcomes the SMR. The electron then resumes inward movement across the HMS.


toroidal nonneutral plasma, pure electron plasma, stochastic magnetic region, helically trapped particle, inward electron orbit, shifted equipotential surface, potential barrier

DOI: 10.1585/pfr.5.S2066


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This paper may be cited as follows:

Haruhiko HIMURA, Mitsutaka ISOBE, Akihiro SHIMIZU and Sadao MASAMUNE, Plasma Fusion Res. 5, S2066 (2010).