Analysis of Surface Charge Accmulation and Current Pulse Characteristics in a Lossy Dielectric under Needle-Plane Electrodes Considering Different Electrical Conductivity Models

This paper investigates the effects of electrical conductivity models of a lossy dielectric on current pulses and surface charge accumulation in a needle-plane electrode system. Two constant-conductivity cases were compared with a nonlinear model dependent on electric field and temperature. For the nonlinear model, uniform 30°C and temperature-gradient conditions were considered separately. The constant-conductivity cases showed similar pulse magnitudes but different timings, while the temperature-fixed nonlinear model caused only limited changes. In contrast, the temperature-gradient model produced clear differences in current pulses and surface charge distribution. At the same interface position, the surface charge density decreased by about 90%, and the location of maximum charge accumulation shifted. These results show that spatial variations in conductivity due to electric field and temperature significantly affect transient discharge and interfacial charge behavior.