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Title: Experimental test of whether electrostatically charged micro-organisms and their spores contribute to the onset of arcs across vacuum gaps

Recently it was proposed [L. R. Grisham et al. Phys. Plasmas 19, 023107 (2012)] that one of the initiators of vacuum voltage breakdown between conducting electrodes might be micro-organisms and their spores, previously deposited during exposure to air, which then become electrostatically charged when an electric potential is applied across the vacuum gap. This note describes a simple experiment to compare the number of voltage-conditioning pulses required to reach the nominal maximum operating voltage across a gap between two metallic conductors in a vacuum, comparing cases in which biological cleaning was done just prior to pump-down with cases where this was not done, with each case preceded by exposure to ambient air for three days. Based upon these results, it does not appear that air-deposited microbes and their spores constitute a major pathway for arc initiation, at least for exposure periods of a few days, and for vacuum gaps of a few millimeters, in the regime where voltage holding is usually observed to vary linearly with gap distance.
Authors:
; ; ; ; ;  [1]
  1. Princeton University Plasma Physics Laboratory, P. O. Box 451, Princeton, New Jersey 08543 (United States)
Publication Date:
OSTI Identifier:
22224186
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 12; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 60 APPLIED LIFE SCIENCES; AIR; COMPARATIVE EVALUATIONS; ELECTRIC POTENTIAL; ELECTRODES; MICROORGANISMS; PLASMA; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PULSES; SPORES