Gas Temperatures and Elastic Losses in Low Pressure Mercury-Argon Discharges

The increase ΔT in average gas temperature for ac and dc has been determined from measurements of the increase in pressure. A small McLeod gauge was used. Wall temperature was regulated. Corrections for end effects were made by comparing results for long and short tubes of 3.6 cm diameter. Assuming the radial variation of heat input to be parabolic, the temperature distribution was calculated using published values of heat conductivity K. From the results the heat input Pm per centimeter length was calculated. This value was compared with the elastic loss Pc computed from electron temperature Te and number of electrons Ne per centimeter column, taking into account the variation of mean free path with electron velocity. Good agreement was obtained for mercury pressures ranging from 1 to 25 microns, with the arc current 0.2–0.6 ampere and the argon filling pressure 3.5 mm (Hg).