Thumbnail
Access Restriction
Open

Author Davidson, R. C. ♦ Chao, E. H.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ PLASMA WAVES ♦ ELECTRON-ATOM COLLISIONS ♦ ELECTRON GAS ♦ INSTABILITY GROWTH RATES ♦ ELECTRON COLLISIONS ♦ EIGENSTATES
Abstract This paper investigates theoretically the electrostatic stability properties of a nonneutral electron plasma interacting with background neutral gas through elastic collisions with constant collision frequency {nu}{sub {ital en}}. The model treats the electrons as a strongly magnetized fluid ({omega}{sub {ital pe}}{sup 2}/{omega}{sub {ital ce}}{sup 2}{lt}1) immersed in a uniform magnetic field {ital B}{sub 0}{bold {cflx e}}{sub {bold z}}, and assumes small-amplitude perturbations with azimuthal mode number l=1 and negligible axial variation ({partial_derivative}/{partial_derivative}{ital z}=0). The analysis also assumes weak electron collisions with {nu}{sub {ital en}}/{omega}{sub {ital ce}}={epsilon}{lt}1, and that the process of heat conduction is sufficiently fast that the electrons have relaxed through electron-electron collisions to a quasiequilibrium state with scalar pressure {ital P}({ital r},{theta},{ital t})={ital n}({ital r},{theta},{ital t}){ital T}, and isothermal temperature {ital T}. Assuming that perturbed quantities vary with time according to exp({minus}{ital i}{omega}{ital t}), the detailed stability analysis carried out to first order in {nu}{sub {ital en}}/{omega}{sub {ital ce}}{lt}1 shows that the real oscillation frequency and growth rate for the l=1 diocotron mode are given, respectively, by the simple expressions Re{omega}={omega}{sub 0} and Im{omega}=({nu}{sub {ital en}}/{omega}{sub {ital ce}}){omega}{sub 0}. Here, {omega}{sub 0}={ital Nec}/{ital r}{sup 2}{sub {ital wB}}{sub 0}, where {ital r}{sub {ital w}} is the perfectly conducting wall radius, and {ital N}={integral}{ital d}{sup 2}{ital x}{ital n} is the number of electrons per unit axial length. This analysis suggests that a measurement of the oscillation frequency and growth rate for the l=1 diocotron mode can be used to infer {nu}{sub {ital en}}, and thereby serve as a sensor for the background neutral pressure. {copyright} {ital 1996 American Institute of Physics.}
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-09-01
Publisher Department Princeton Plasma Physics Laboratory
Publisher Place United States
Journal Physics of Plasmas
Volume Number 3
Issue Number 9
Organization Princeton Plasma Physics Laboratory


Open content in new tab

   Open content in new tab