The expansion of the cathode spot plasma in vacuum arc discharges
- 1 June 1987
- journal article
- research article
- Published by AIP Publishing in Physics of Fluids
- Vol. 30 (6), 1810-1813
- https://doi.org/10.1063/1.866195
Abstract
A stationary one‐dimensional two‐fluid model for the expansion and corresponding acceleration of the dense cathode spot plasma in vacuum arc discharges is evaluated. The equations exhibit a saddle point at the ion sound velocity. For an acceleration to supersonic velocities, the effect of Joule heating due to electron–ion collisions has to compensate for the effect of geometrical dilution at the sonic point. As a consequence, a transsonic flow is possible for a specific ion starting velocity only. This model shows that large final ion velocities observed in experiments are mainly caused by the directed friction force due to electron–ion collisions. A small potential hump has only a minor effect for the momentum gain of the ions.Keywords
This publication has 3 references indexed in Scilit:
- Constraints imposed upon theories of the vacuum arc cathode region by specific ion energy measurementsJournal of Applied Physics, 1981
- Analysis of the Electrode Products Emitted by dc Arcs in a Vacuum AmbientJournal of Applied Physics, 1969
- On the Cathode of an Arc Drawn in VacuumPhysical Review B, 1930