Streamer Inception in Cyclohexane Above and Below Freezing Point

Streamer inception as a function of temperature was studied in pure cyclohexane in needle-plane geometry under impulse voltage with a positive needle electrode. The temperature of the sample volume was regulated to 0, 20, 40 and 60degC, where 0degC is below the freezing point of cyclohexane (6degC). A sensitive differential charge measurement, with sensitivity down to 0.1 pC, and a photomultiplier was used to study the discharges in the liquid and solid phase. Streamer inception probabilities, total injected charge and photomultiplier readings were compared at the four different temperatures. Only small differences were observed as a result of increasing the temperature from 20degC to 60degC. This consisted in a small decrease in injected charge and a slightly lower pre-inception current when the temperature was increased. When going from liquid to frozen cyclohexane a marked difference was seen for all properties measured.