Townsend's First Ionization Coefficient for Compressed Nitrogen

Abstract

THERE is a growing interest in the use of compressed gases, especially nitrogen and sulphur hexafluoride, for high-voltage insulation. However, there have been few measurements of the fundamental parameters, such as the Townsend α-coefficient, in gases at pressures above atmospheric. Allen¹ has made measurements at pressures up to 4 atmospheres absolute in nitrogen and has shown that, for values of E/p (electric stress/pressure) greater than 40 (V/cm)/mm mercury, the value of α agrees well with results from work at pressures below atmospheric. In the work recorded here it has been possible to extend measurements in high-pressure nitrogen down to E/p₀ = 31.5 (V/cm)/mm mercury (p₀ is the pressure corrected to 0° C) with pressures up to 10 atmospheres.