Plasma Ion Oscillation in a Plasma-Beam System

Abstract

Plasma ion oscillations have been studied in a plasma produced by hot-cathode, mercury-vapour discharge, at a pressure of about 1 μHg. A super-heterodyne detector and a movable probe were employed to observe frequency spectra at different points in a small tube having plane electrodes.
The frequencies of the self-sustained plasma ion oscillations were markedly dependent on the position in the tube, and the frequencies of the ion oscillations on the inside of a beam were lower than that on the outside.
In order to explain our observation, a simple theory of plasma ion oscillation in a plasma-beam system is proposed.