Abstract
We have studied current transients of pre-breakdown electron avalanches in uniform fields in pure oxygen, and in mixtures of oxygen and hydrogen. The goal of this work is to determine an effective first Townsend coefficient , which accounts for instantaneous ionization processes by electron impact. Following the reasoning of Price, Lucas, and Moruzzi, the mixtures were chosen to remove the primary negative ion by a rapid associative detachment reaction with , thus effectively making oxygen behave as a nonattaching gas. This simplifies the analysis of the transients. A simple extrapolation to zero hydrogen pressure is used to determine , the ratio of the ionization coefficient to pure oxygen pressure. The values of thus obtained are in agreement with pulse measurements in pure oxygen and supplement the pure oxygen data at lower field-strength-to-pressure ratios (between 30 to 40 V/cm Torr) and at higher pressures (16 to 32 Torr). Because of the observed presence of a detachment reaction in the mixture, the role of associative detachment in making oxygen behave as a nonattaching gas is reexamined.
- Received 3 June 1974
DOI:https://doi.org/10.1103/PhysRevA.10.2273
©1974 American Physical Society