[Table of Contents]

Plasma and Fusion Research

Volume 7, 1302098 (2012)

Letters

Detection of Vertical Charge Separation Current in a Toroidal ECR Plasma by Radially Aligned Multi-Electrodes
Kengoh KURODA, Masaki UCHIDA, Hitoshi TANAKA and Takashi MAEKAWA
Graduate School of Energy Science, Kyoto University, kyoto 606-8502, Japan
(Received 23 March 2012 / Accepted 23 May 2012 / Published 26 July 2012)

Abstract

In plasmas immersed in the toroidal field Bφ, electrons drift downward while ions drift upward due to the field gradient and curvature (Bφ > 0 is assumed). The plasma is usually bounded at the top and bottom by the conducting vessel walls. The same amount of current must flow into and out from the walls at the top and bottom, respectively, to complete the current circulation via the vacuum vessel. In an ECR plasma in the LATE device radial profiles of vertical charge separation currents have been for the first time measured by radially aligned multi-electrodes fabricated at the top and bottom. Both the profiles at the top and bottom are nearly the same as the profile 2Pe/RBφ in the plasma as theoretically predicted. Current characteristics upon the sweep of external voltage onto the top ion collectors reveal that the current is due to inflow of ions with no secondary electron emission.

Keywords

ECR plasma, VTF drift, charge separation current, current circulation

DOI: 10.1585/pfr.7.1302098

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This paper may be cited as follows:

Kengoh KURODA, Masaki UCHIDA, Hitoshi TANAKA and Takashi MAEKAWA, Plasma Fusion Res. 7, 1302098 (2012).