Accommodation Coefficients of Positive Ions of Argon, Neon and Helium

Abstract

Positive ions of argon, neon and helium produced in a low voltage arc were attracted to a spherical metal collector by regulated potentials up to 140 volts. The resulting heating of the collector was measured by a thermal junction and found to be considerably less than the product of the current by the attracting voltage. After taking account of the energy scattering at collisions and of the effect of the secondary electron emission, the following values of the "accommodation coefficients" were obtained: argon 0.75±0.05, neon 0.65±0.05 (both between 21 and 141 volts), and helium 0.35±0.05 between 21 and 51 volts and 0.55±0.05 between 111 and 141 volts.