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Media type:
E-Article
Title:
The expansion of the cathode spot plasma in vacuum arc discharges
Contributor:
Wieckert, Christian
imprint:
AIP Publishing, 1987
Published in:The Physics of Fluids
Language:
English
DOI:
10.1063/1.866195
ISSN:
0031-9171
Origination:
Footnote:
Description:
<jats:p>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.</jats:p>