Prebreakdown current pulses at a point cathode in highly purifiedliquid hexane have been observed to be affected by hydrostatic pressurefrom below one atmosphere to several atmospheres. Previously, carefulcombination of low-noise, high-bandwidth detection techniques hadrevealed these random currents actually to be well-separated burstsinitiated at apparently random times, but each burst was awell-structured set of systematically spaced pulses with successiveamplitudes related in an increasing linear manner. It has been observedthat increasing the hydrostatic pressure reduces the duration of eachburst and the number of pulses within it. A hybrid model for growth ofthe low-density region (LDR) has been developed by combining two earliermodels in a mutually enhancing iteration, and reasonable agreement hasbeen obtained with experimental observations. It appears that each burstcorresponds to growth and dissipation of one LDR, and each set ofincreasingly larger pulses corresponds to breakdowns within theincreasingly larger LDR as its potential changes during its expansion.An experimental means has been developed to vary hydrostatic pressurewithout exposure to gases, moving seals, contaminants, or changes intest liquid conditions other than pressure
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