LIGHT MEASUREMENTS IN VACUUM GAPS.
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
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The intensity of light emitted from a gap prior to breakdown was measured as a function of voltage for gap spacings of 0.5 to 3.0 mm at 0.5 mm settings. The onset of visible light was found to occur at the same current level for any gap spacing. Four levels of infrared output were measured for the various gap spacings. A constant detector output was used as a criterion of electrode surface disruption. These measurements show that the slopes of the curves of units of infrared versus gap spacing vary from about 0.8 at the lowest level to 0.6 at the highest light intensity output level, which is just below a breakdown level. These measurements verify Cranbergs half-power law, and also might explain why other experimenters using various criteria for breakdown obtained various values of alpha. Author