The effect of air pressure on the surface electric field intensity characteristics under negative DC corona discharge in a corona cage

摘要

The accuracy of surface electric field (SEF) is important for the research of corona discharge, both in numerical simulation and actual application. However, it is widely considered that the SEF is invariable after corona occurs (Kaptzov's assumption). This theory makes corona study more convenient, but slightly inconsistent with the actual situation. In this work, the influence of air pressure on SEF intensity and distribution of space charge density under negative DC corona discharge is studied in corona cage via sound pulse method and maximum charge density ratio. The most important finding in this work is that when the voltage gradient is greater than the onset voltage, contrary to popular perception, SEF is not a fixed value and lower than the onset field intensity. And a linear negative correlation between the space charge density and the SEF intensity after the corona initiates is found for the first time. In addition, the SEF intensity has a decreasing trend with the applied voltage rising after corona initiates, and rises slightly with the increase of air pressure. The change of space charge density with applied voltage and air pressure is opposite to the change of electric field.