Current density at the local discharge tip on an electrolytic surface

Experimental results are presented on the current density at the local discharge tip on electrolytic surfaces, which simulate the surfaces of wet polluted insulators. A rod-plane electrode system with the electrolyte layer on the plane electrode was used inside a Pyrex glass chamber. The air pressure in the chamber was changed from ~6.67 to 101 kPa. The resistivity of the aqueous solution of potassium chloride was changed from ~A 10 to 880 Ω-cm. The current density at the interface between the local discharge tip and the electrolytic surface was measured by two methods (one with the probes set in an electrolyte, the other using a camera to photograph the local discharge tip). As a result, it was found that the current density was constant, regardless of the discharge current and that it increased with air pressure and decreased with an increase of the resistivity of the electrolytic solution