[Table of Contents]

Plasma and Fusion Research

Volume 3, S1011 (2008)

Regular Articles

Drift-Wave Instabilities Modified by Parallel and Perpendicular Flow Velocity Shears in Magnetized Plasmas
Toshiro KANEKO, Shuichi TAMURA, Atsushi ITO1) and Rikizo HATAKEYAMA
Department of Electronic Engineering, Tohoku University, Sendai 980-8579, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 7 December 2007 / Accepted 29 January 2008 / Published 1 August 2008)

Abstract

Plasma flow velocity shears parallel and perpendicular to magnetic field lines are independently controlled and superimposed by a modified plasma-synthesis method with concentrically three-segmented electron and ion emitters. The fluctuation amplitude of a drift wave with an azimuthal mode number m = 3 is observed to increase with increasing parallel shear strength in the absence of a perpendicular shear. When the perpendicular shear is superimposed on the parallel shear, the drift wave with m = 3 is found to transform into that with m = 2. Furthermore, the parallel shear strength required for excitation of the drift wave increases with a decrease in the azimuthal mode number. Based on these results, superposition of the parallel and perpendicular shears can affect characteristics of the drift wave through variation of the azimuthal mode number. These phenomena can be verified by theoretical calculations of the growth rate of the drift wave using an eigenmode analysis.

Keywords

plasma flow velocity shear, drift wave, azimuthal mode number, plasma-synthesis method

DOI: 10.1585/pfr.3.S1011

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This paper may be cited as follows:

Toshiro KANEKO, Shuichi TAMURA, Atsushi ITO and Rikizo HATAKEYAMA, Plasma Fusion Res. 3, S1011 (2008).