Measurement of neutral gas density with ionization gauges in plasma physics research

Abstract

The assessment of neutral gas density in the vicinity of a magnetically confined plasma is necessary for the consideration of atomic processes in fusion research experiments. Ionization gauges can be used provided that steps are taken to restrict the influence of the magnetic field on their sensitivity and to effect the differentiation of the true signal from the plasma produced background. In addition, the gauges must have a rather short time constant and a large signal-to-noise ratio. This paper presents an analysis of the features mentioned, based on a careful review of the literature to date. The results achieved by different research workers are discussed within the frame of the foregoing analysis. An attempt to correlate the design criteria underlying the operation of ionization gauges used in plasma machines is presented.