Modern theory of corona discharge

The principles of the modern theory of corona discharge are presented. The theory considers bimodality, sudden current transitions, the difference between the onset and offset potentials, i.e., hysteresis, and other features of the corona following from the cusp catastrophe topology. The relation of this topology to the corona discharge mechanisms is discussed. It is shown that the topology of the cusp catastrophe is generated by processes that are nonlinear with respect to corona current; they are pair ionizing collisions of metastable particles and the local heating of the medium filling the discharge gap near the stressed electrode. Considering this fact one can view the theory as a nonlinear corona discharge theory. The theory predicts the possibility of self-sustained oscillations and also the contraction phenomenon in a corona discharge. Some features of corona discharge in helium and in helium with an admixture of oxygen are considered