Ecton mechanism for the generation of ion flows in a vacuum arc

Abstract

The principal characteristics of the process of generation of the cathode plasma in a vacuum arc (ion erosion, mean charge of ions) are considered in terms of the ecton model of the cathode spot of a vacuum arc. The estimates of the parameters of ions obtained for a unit cell of a cathode spot – an ecton – are in good qualitative and quantitative agreement with experimental data. The following mechanism for the generation of the cathode plasma of a vacuum arc is proposed. When a region of the cathode is destroyed in an explosive manner due to Joule heating, the material of the cathode sequentially goes over a series of states: the condensed state and the states of imperfect and ideal plasma. During this transition the charge state of the plasma is formed and the ions are accelerated under the action of the pressure gradient in the plasma whose density decreases by several orders of magnitude over distances of ∼10 μm from the cathode surface. The increase in current results in an increase in number of cells, and the principal parameters of the ions are formed as a result of the operation of a unit cell of the spot.