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Publication
Detailed numerical simulation of cathode spots in vacuum arcs—I
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Advisor(s)
Abstract(s)
A model of cathode spots in high-current vacuum
arcs is developed, with account of the plasma cloud left over from
a previously existing spot, all mechanisms of current transfer to
the cathode surface, including the contribution of the plasma
produced by ionization of the metal vapor emitted in the spot,
and the Joule heat generation in the cathode body. The simulation
results allow one to clearly identify the different phases of
life of an individual spot: the ignition, the expansion over the
cathode surface, and the thermal explosion. The expansion phase
is associated with a nearly constant maximum temperature of
the cathode, which occurs at the surface and is approximately
4700–4800 K. Thermal explosion is a result of thermal instabil ity (runaway), which develops below the cathode surface when
the Joule heating comes into play. The development of the spot is
interrupted if the plasma cloud has been extinguished: the spot
is destroyed by heat removal into the bulk of the cathode due to
thermal conduction. Therefore, different scenarios are possible
depending on the time of action of the cloud: the spot may be
quenched before having been formed or during the expansion
phase, or even at the initial stage of thermal explosion.
Description
Keywords
Arc discharges Electrodes Vacuum arcs . Faculdade de Ciências Exatas e da Engenharia
Citation
Cunha, M. D., Kaufmann, H. T., Benilov, M. S., Hartmann, W., & Wenzel, N. (2017). Detailed numerical simulation of cathode spots in vacuum arcs—I. IEEE Transactions on Plasma Science, 45(8), 2060-2069. DOI: 10.1109/TPS.2017.2697005
Publisher
Institute of Electrical and Electronics Engineers