The possibility of photodetachment in the impulse breakdown of positive point - plane gaps in air

The relative importance of the roles of photodetachment and photoionization in the propagation of positive point-plane impulse corona in air is discussed. Consideration of the magnitudes of the cross sections for the two mechanisms as a function of photon energy reveals a higher efficiency for the photodetachment process. Further support for the conclusion that photodetachment is more probable than photoionization, in the circumstances considered, is drawn from experimental evidence such as the visual form of the corona and its dependence upon meteorological conditions.