Analysis of ionization non-equilibrium in the near-cathode region of atmospheric-pressure arcs

Deviations from ionization equilibrium in the near-cathode region of a high -pressure high-current are are analysed. Estimates and numerical calculatio ns are given for an atmospheric-pressure argon are. It is found that the de viations extend over the distance of about 100 mu m from the cathode surfac e and are caused by ambipolar diffusion; convective transport of the charge d particles, barodiffusion, thermal diffusion, diffusion caused by thermal non-equilibrium between electrons and heavy particles, and transport due to the presence of the electric current are minor effects.