Date of Award

5-18-2008

Document Type

Honors Thesis

Department

Physics

First Advisor

Hans Pfister

Language

English

Abstract

Plasma thrusters have found increasing application for station-keeping of earth orbiting satellites as well as some interplanetary missions, yet a few of the finer details of the basic plasma physics of these thrusters remain unresolved. Recently, we discovered an oscillatory interaction between the discharge current and the current for the radial magnetic field in Dickinson College’s closed drift plasma Hall thruster. Similar oscillations were found and reported for the first time by Yu et al. [Plasma Sources Sci. Technol. 16, Sept. 2007], who refer to this interaction as a “coupling oscillation.” In this phenomenon, azimuthally E x B-drifting electrons create a Hall current, which produces a magnetic field opposing the thruster’s applied radial magnetic field. As the electron Hall current “destroys” this crucial radial magnetic field, the discharge current approaches zero. Yet, just as the discharge current diminishes, the Hall current approaches zero as well, thereby reducing its “destructive” or counteractive effect on the thruster’s radial magnetic field. This effect begets the return of a “normal” radial magnetic field and discharge current, causing the coupled cycle to begin again, thereby producing the fascinating oscillatory interaction that we observe.

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