A Mathematical Analysis of the Glow and Dark Space Regions in Positive Corona

The authors present a mathematical analysis of the electric field, current density, and charge density in the entire airgap in positive dc corona in cylindrical geometry. The currents are found using the Townsend breakdown theory and the Sarma empirical equation for the ionization coefficient in air. Since the ionization coefficient is a function of the local field intensity and the electric field distribution depends on the ionization process, an iterative numerical method was used. White-head's empirical formula describing the conductor surface onset field intensity as a function of the conductor radius was used to establish the field intensity at the point in the gap where the ionization process begins. The results show good agreement with available experimental data on particle-charging.