Measurements of ionization and attachment coefficients in chlorine

Ionization and attachment coefficients, α and η, have been obtained by observing, in pure chlorine at pressures of from 1 to 10 torr, the variation of prebreakdown ionization currents with the distance between parallel electrodes at reduced fields in the range 70-150 v cm -1 torr -1 . Values of α - η have been obtained for values of E/p up to 250 v cm -1 torr -1 . The reduced coefficient α/ p rises from 0·22 at E/p = 70 to 2·0 at E/p = 150, while η/ p falls from 0·84 to approximately 0·25 in the same range. No pressure dependence could be found. These values of the attachment coefficient are much larger than those indicated by an extrapolation of the results of Bailey and Healey.