Ionization and attachment in oxygen at low pressures

From measurements of pre-breakdown currents across plane-parallel electrodes, and with the aid of a simple analysis developed here, ionization and attachment coefficients have been evaluated for 50 < E/p 0 < 250 v cm −1 torr −1 . Values of the attachment coefficient are found to reduce to practically zero at about 70 v cm −1 torr −1 , which could indicate a detachment process. Sparking potentials were also measured in the range 0·1 < p 0 d < 5 cm torr, and this enabled the evaluation of generalized secondary coefficients.