Distribution of stems around the HV electrode in a 0.74-m air gap under positive pulses

A schlieren system with a temporal resolution of 5 μs and a spatial resolution of 70 μm was established; it was used to examine the spatial distribution of stems around different HV electrodes in a 0.74-m air gap under positive impulses. The results show that there is always more than one stem developing from the HV electrode surface. On the basis of the high spatial resolution of schlieren photographs, the distribution of stems around the HV electrode is investigated considering the influence of the curvature radius of the electrode and the rising rate of the voltage impulse.