Date of Award

Spring 1991

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Glenn A. Gerdin

Committee Member

Karl H. Schoenbach

Committee Member

Linda Vahala

Call Number for Print

Special Collections LD4331.E55N565

Abstract

In a low pressure discharge, if the cathode incorporates a cylindrical or slit shaped hole, the discharge current can be several orders of magnitude higher than in one with plane parallel electrodes under the same pressure and voltage conditions. In this work hollow cathode discharges in Helium under the influence of variable parameters such as gas pressure, applied voltage, electrode gap spacing, external magnetic field, etc., are investigated by means of electrical and optical diagnostic techniques.

The results indicate that a hollow cathode discharge develops in two stages. The initial breakdown occurs along the longest straight path of the system, i.e., from the anode to the bottom of the cathode hole. This predischarge is confined to a narrow filament along the axis and carries a current up to l00's of mA. The resulting distortion of the electric field in the cathode hole is assumed to cause a subsequent radial breakdown from the filamentary plasma on the axis to the edge of the cathode hole. After this second breakdown an increase in current by more than three orders of magnitude is observed. Experimental results with axial magnetic fields support the two-stage model.

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DOI

10.25777/zjav-kn59

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