A parametric study of DC-RF Penning-type plasma discharge

A plasma cathode that utilizes electron extraction from a rf-plasma (2 MHz, 30-100 W) is shown to sustain a high current (1-5 A) operation of a low pressure (0.1-1 mtorr) dc discharge with applied magnetic field (0.01-1 kGauss) in the discharge voltage range of 20-100 V. Probe measurements of plasma potential, electron temperature and density revealed a strong effect of the magnetic field on plasma properties of this discharge. For example, at the discharge voltage of 50 V, the voltage potential drop in the magnetized part of the discharge increases from a few volts to about 20 V as the magnetic field increases from 35 to 160 Gauss. It is shown that the electron cross-field current in the Penning discharge is anomalously high and cannot be explained by classical collisional mechanism.