Self-similar gas motion near the evaporating electrode of an electric arc

Simple solutions of 1Dt gas-dynamical equations based on similarity analysis are possible for the gas surrounding a point source of mass and energy such as an electrode (cathode) are spot. To obtain nontrivial (non-zero temperature) solutions throughout, two-scale formulation is used that permits an additional boundary condition near the source. Three generalised gas flow variables, R, Z and V, related to gas density, temperature and velocity are calculated and presented as functions of a single similarity parameter, lambda, related to position and time. The computational results are compared with data from two gas discharge experiments: on gas disturbances due to an electric are of micrometer length in atmospheric air and on expansion of a metal-vapour plasma cloud generated by a lo rv-pressure cold-cathode arc.