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Proceedings Paper

Dependence of nonstationary behavior of arc cathode spots on discharge duration
Author(s): B. Juettner; W. Loeffler; C. Weber; G. Ziegenhagen
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Paper Abstract

In nanosecond vacuum arc discharges, the size of cathode plasmas has been found to have the order of 10 micrometers . This outcome has decisive consequences for particle density, current density, time constants, and radiation properties. The present paper explores the question whether there occur principal changes in longer discharges. Experimental methods were: imaging the spots of microsecond(s) -discharges by absorption and emission techniques, and monitoring the shape of spectral lines in the range of nanoseconds through milliseconds. It has been found that in the light of atomic or ionic lines the diameter of emission pictures have the order of 100 micrometers , irrespective of the discharge duration in the range 10 ns through 100 microsecond(s) . Pictures obtained by differential laser absorption in the time range 100 ns through 50 microsecond(s) yielded a size <EQ 30 micrometers . Time-integrated analysis of emitted spectral lines yielded broadened profiles for discharges of 800 ns duration with a FWHM (full width at half maximum) up to 0.5 nm. This indicates the effect of high densities and magnetic fields, possible only with small spots. The same has been found for discharge durations up to 100 ms. Thus, it is suggested that the spot size remains small up to discharge durations of milliseconds. This outcome is associated with a principal non-stationary spot nature.

Paper Details

Date Published: 1 May 1994
PDF: 6 pages
Proc. SPIE 2259, XVI International Symposium on Discharges and Electrical Insulation in Vacuum, (1 May 1994); doi: 10.1117/12.174611
Show Author Affiliations
B. Juettner, Max-Planck-Institut fuer Plasmaphysik (Germany)
W. Loeffler, Max-Planck-Institut fuer Plasmaphysik (Germany)
C. Weber, Max-Planck-Institut fuer Plasmaphysik (Germany)
G. Ziegenhagen, Max-Planck-Institut fuer Plasmaphysik (Germany)


Published in SPIE Proceedings Vol. 2259:
XVI International Symposium on Discharges and Electrical Insulation in Vacuum

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