A two-dimensional nonstationary model of the initiation of an explosive center beneath the plasma of a vacuum arc cathode spot

Abstract

A numerical two-dimensional non-stationary model is developed to study the initiation of new explosive center beneath the plasma of a vacuum arc cathode spot. The process of heating of a cathode surface microprotrusion has been simulated numerically. The obtained results of this paper show that taking into account the ion impact heating and the electric field of the space charge zone near the cathode surface ensure the "triggering" heat flux power necessary for the development of the Joule heating of the microprotrusion followed by it explosion at reasonable values of the ion current and of the geometric parameters of the microprotrusion.

On the mechanism of operation of a cathode spot cell in a vacuum arc

“…During the first stage, the protrusion is heated by the plasma ions, whereas during the second stage, which begins as the surface temperature approaches the melting point of tungsten (3500-4000 K), resistive heating becomes substantial as the emission current increases with temperature. 11,12 At this stage, the emission current density at the liquid-metal protrusion reaches $10 8 A/cm 2 . The current density at the jet base, j b , will be geometrically enhanced by a factor of S s /S b , where S s is the surface area of the jet and S b is its base area.…”

The effect of cathode deuteration on the parameters of vacuum-arc plasma

“…The possibility of realization of the explosive electron emission conditions in the cathode spot of vacuum arc has been discussed for a long time. However, at present, it can be ascertained that the interaction of dense near cathode plasma with microinhomogene ities on the cathode surface unavoidably leads to the initiation of explosive electron emission [6][7][8].According to the proposed model, the cathode spot of a deuterated zirconium electrode features simulta neous erosion of deuterium and zirconium. It is assumed that the ratio of erosion rates of these compo nents is determined by the degree of electrode satura tion with deuterium and does not change with the time.…”

Ignition and sustainment of the explosive electron emission cyclic pulses — Ectons by plasma-surface interaction

“…Numerical modeling has been performed for the plasma action onto the wall having a microprotrusion with taking into account the thermo-field-emission, 2D thermal balance, heating by incident plasma, sheath properties, see [8][9].…”