1 May 1994 Appearance of vacuum-arc cathode spots imaged by emitted light
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Proceedings Volume 2259, XVI International Symposium on Discharges and Electrical Insulation in Vacuum; (1994) https://doi.org/10.1117/12.174625
Event: XVI International Symposium on Discharges and Electrical Insulation in Vacuum, 1994, Moscow-St. Petersburg, Russian Federation
Abstract
The present paper discusses the appearance of arc cathode spots observed in emission. Photographs yield a size of about 100 micrometers when using line radiation, whereas imaging by absorption techniques or emission pictures with continuum radiation result in values of about 10 micrometers , comparable to the crater traces left at the surface. Besides the size, the slope of the spot profiles is considered. Experimentally, it is found that the light intensity decreases with the distance r from the spot center proportional to r-2. This slope is much less than the expected dependence proportional to r-(beta), (beta) > 4, i.e. the observed spot edge is much less sharp than expected. The behavior of the radiation is theoretically studied by modeling the radial dependence of particle densities and temperature. It is shown that the line radiation stems from a region which is greatly influenced by the plasma expansion in competition with the finite transition probability of excited levels. It is concluded that emission pictures of cathode spot yield considerably higher spot diameters than corresponding to the spot core.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Erhard Hantzsche, Erhard Hantzsche, B. Juettner, B. Juettner, } "Appearance of vacuum-arc cathode spots imaged by emitted light", Proc. SPIE 2259, XVI International Symposium on Discharges and Electrical Insulation in Vacuum, (1 May 1994); doi: 10.1117/12.174625; https://doi.org/10.1117/12.174625
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