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Publication
Simulating changes in shape of thermionic cathodes during operation of high-pressure arc discharges
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Advisor(s)
Abstract(s)
A numerical model of current transfer to thermionic cathodes of high-pressure arc discharges
is developed with account of deviations from local thermodynamic equilibrium occurring
near the cathode surface, in particular, of the near-cathode space-charge sheath, melting of the
cathode, and motion of the molten metal under the effect of the plasma pressure, the Lorentz
force, gravity, and surface tension. Modelling results are reported for a tungsten cathode of
an atmospheric-pressure argon arc and the computed changes in the shape of the cathode
closely resemble those observed in the experiment. The modelling has shown that the time
scale of change of the cathode shape during arc operation is very sensitive to the temperature
attained by the cathode. The fact that the computed time scales conform to those observed
in the experiment indicate that the model of non-equilibrium near-cathode layers in high pressure arc discharges, employed in this work, predicts the cathode temperature for a given
arc current with adequate accuracy. In contrast, modelling based on the assumption of local
thermodynamic equilibrium in the whole arc plasma computation domain up to the cathode
surface could hardly produce a similar agreement.
Description
Keywords
Thermionic cathodes High-pressure arc discharges Deviations from local thermodynamic equilibrium Motion of the molten metal . Faculdade de Ciências Exatas e da Engenharia
Citation
Cunha, M. D., Kaufmann, H. T. C., Santos, D. F. N., & Benilov, M. S. (2019). Simulating changes in shape of thermionic cathodes during operation of high-pressure arc discharges. Journal of Physics D: Applied Physics, 52(50), 504004.
Publisher
IOP Publishing