Mechanism of ion flow generation in vacuum arcs

The ecton model of the cathode spot is used to analyze the main parameters of ion flow in vacuum arcs (ion erosion, mean charge, and velocity). It is shown that the arc plasma is formed as a result of microexplosions at the c athode surface, induced by the Joule heating by the high-density current of explosive electron emission. Ionization processes are localized in a narro w region of the order of a micrometer near the cathode and the ionization c omposition of the plasma subsequently remains unchanged. Under the action o f the electron pressure gradient, ions acquire directional velocities of th e order of 10(6) cm/s even over small distances of the order of several mic rometers. (C) 2001 MAIK "Nauka/Interperiodica".