Electrical breakdown of mercury vapour between mild steel planar parallel electrodes†

Abstract

A preliminary study of the breakdown potential of mercury vapour between mild steel planar parallel electrodes at various gas temperatures is reported. The product of gas pressure times electrode gap length (p 0 d) is varied over the range 1·25 × 10−2 to 4·28 × 10−1 torr cm. The breakdown potential value shows a sharp increase with a slight decrease in the value of p 0 d at about 7 × 10−2 torr cm. At low gas pressures, on the left-hand side of the Paschen curve, the plot of the breakdown potential against p 0 d shows the normal behaviour where it increases with decreasing gas pressure. A search has been made for the presence of widely different values of breakdown potential, such as those reported by Guseva and Klyarfeld (1954), at a fixed value of p 0 d. However, no multiple values of breakdown potential could be observed at any single value of p 0 d. At a gas pressure of 1·65 × 10−3 torr and temperature of 297°K the measured breakdown potential value is 69·5 kV. This breakdown potential value is thought...