Study of streamer inception in cyclohexane with a sensitive charge measurement technique under impulse voltage

This paper presents an experimental study of streamer initiation in liquid cyclohexane. The aim is to compare specific features of streamer initiation in positive and negative polarity. Experiments are carried out in point-plane geometry under impulse voltage. A new differential charge measurement system is presented. It allows to obtain a high detection sensitivity under impulse voltage (below 0.1 pC). The investigations presented consider the influence of applied voltage, impulse rise time, hydrostatic pressure. As previously observed under DC voltage, negative streamer initiation is due to an avalanche in the liquid phase, and is not affected by pressure, up to 10 MPa. In contrast, the mechanisms leading to positive streamer initiation are not clearly established. In this polarity, an increase of streamer initiation voltage is observed when the pressure is raised.