Plasma and Fusion Research

Volume 3, S1020 (2008)

Regular Articles

Instability Driven by a Finitely Thick Annular Beam in a Dielectric-Loaded Cylindrical Waveguide
Shusuke TAMURA, Mitsuhisa YAMAKAWA, Yusuke TAKASHIMA and Kazuo OGURA
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
(Received 16 November 2007 / Accepted 11 March 2008 / Published 1 August 2008)

Abstract

The cherenkov and slow cyclotron instabilities driven by an axially injected electron beam in a cylindrical waveguide are studied using a new version of the self-consistent linear theory considering three-dimensional beam perturbations. There are three kinds of models for beam instability analysis, which are based on a cylindrical solid beam, an infinitesimally thin annular beam, and a finitely thick annular beam. Among these models, the beam shape properly representing the often used actual annular electron beams is the finitely thick annulus. We develop a numerical code for a cylindrical waveguide with a finitely thick annular beam. Our theory is valid for any beam velocity. We present eigen-modes of the cylindrical system with the plasma and beam. Instabilities driven by the annular beam in a dielectric-loaded waveguide are also examined.

Keywords

annular beam, finite thickness, low-frequency surface wave mode, high-frequency surface wave mode, Cherenkov instability, slow cyclotron instability

DOI: 10.1585/pfr.3.S1020

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This paper may be cited as follows:

Shusuke TAMURA, Mitsuhisa YAMAKAWA, Yusuke TAKASHIMA and Kazuo OGURA, Plasma Fusion Res. 3, S1020 (2008).