Plasma Properties and Neutral Gas Densities in Hg‐Rare Gas Discharges

Abstract

The density of the neutral gases in Hg-rare gas discharges and their spatial distribution is controlled by the discharge parameters as well as by the externally adjustable partial pressures. Essential quantities in this context are the gas temperature produced by elastic collisions, the ion transport by the discharge current, the processes governing the wall temperature, and ambipolar diffusion. Despite equal partial pressures different densities may occur, which, i n turn, will influence the parameters of the discharge. This has effects on the assessment of the methods of Hgvapour pressure adjustment and on the evaluation of the measured values. These effects are demonstrated, especially by field strength measurements, for a wide parameter range.

Increased Power Concentration and its Effects on the Discharge Parameters of the Low Pressure Hg‐rare Gas Positive Column. II. Variation of Tube Radius

“…At large field strengths this proportion is twice as great as that calculated from the effective life-times resulting from the tube radius. As already shown in [3], the effective life-time changes the ratio of the spectral lines to each other, but has t 1 c . ..…”

“…Effective life times are used according to the theory of 1113. Recent measurements [12, 131 show deviations, especially for high mercury pressures, but less distinct effect on the calculated efficiencies in the region THg = 42 "C [3]. Extended calculations with measured effective life times are prepared [ 161.…”

Increased Power Concentration and its Effect on the Discharge Parameters of the Low Pressure Hg‐rare Gas Positive Column I. Variation of Current

“…It has, however, an appreciable feed-back effect on the initial density values of the neutral gases, as shown in [9], and also affects the discharge parameters. The mean energy of the radially measured or calculated EEDFs decreases towards the tube wall (Fig.…”

“…The gas temperature, which is primarily governed by the elastic collisions, is usually taken to be constant and homogeneous when describing the column plasma, since compared to the mean electron energy it is much lower and is not relevant to the collision processes. It has, however, an appreciable feed-back effect on the initial density values of the neutral gases, as shown in [9], and also affects the discharge parameters. The mean energy of the radially measured or calculated EEDFs decreases towards the tube wall ( Fig.…”

“…Calculations antl measurements of the EEDF were niatle only for the stationary case of a tlc discharge. I n tlc operation the equipment employed for determining the radiant flux could not prevent axial cataphoresis [9], therefore the flux was determined using a 50 Hz alternating current. A comparison of the results obtained by these two methods is somewhat problematic.…”