Peculiarities of interaction of cathode stream with anode vapors in a vacuum arc

Peculiarities of the slow ion flow movement in the near-anode region of a high-current vacuum arc

“…As previously seen in works [1], [2], we assume that evaporated atoms have semiMaxwellian distribution by the velocities, with the temperature equal to anode temperature , and move without collisions because at typical concentrations of evaporated atoms near the anode -cm , the momentum transfer time considerably exceeds the atom lifetime until the moment of ionization. In this case, the atom flow velocity is constant and equal to half the atom thermal velocity.…”

“…The results obtained in this work, together with mathematical model developed in [1], [2], make a generalized 1-D quasi-stationary four-flow model of VA. This model allows calculating the kinetics of volume ionization of evaporated atoms and distribution of the main parameters describing each flow over the interelectrode gap.…”

“…It was supposed, in particular, that atoms evaporated from the anode are ionized instantaneously at the anode surface and that the high electron thermal conductivity allows us to consider the electron temperature as constant in the interelectrode gap. One of the main results, obtained in works [1], [2] is a conclusion that, in many occasions, a slow ion flow generated by evaporated atoms cannot reach the cathode completely and its largest portion returns to the anode. More detail study of the near-anode region, whose structure is essentially affected by the slow ion flow returning to the anode, leads to a refusal from the assumption about the instantaneous ionization of the evaporated atoms.…”

“…P REVIOUSLY a one-dimensional (1-D) quasi-stationary model of a high-current vacuum arc was considered in three-liquid hydrodynamics approximation [1], [2]. It was supposed, in particular, that atoms evaporated from the anode are ionized instantaneously at the anode surface and that the high electron thermal conductivity allows us to consider the electron temperature as constant in the interelectrode gap.…”

“…The coordinate system and notations of parameters and dimensional and dimensionless variables are the same as those used in works [1], [2].…”