Primary Ionization Coefficient of Helium

Abstract

Ionization currents in spectroscopically pure helium between plane parallel silver electrodes at separations up to 0.75 cm were measured in the range 6 leq E/p leq 100 v cm-1 mmHg-1 and 3 leq p leq 115 mmHg where E is the applied electric field and p the gas pressure. The values of the primary ionization coefficient α/p deduced from these measurements were lower than previously published experimental values, particularly at the lowest range of E/p. Within the limits of experimental error α/p was found to be a function of E/p only.