Electron Swarm Behavior in Nonuniform Field

The comparison of the electron transport properties is presented under nonuniform fields with their local fields in oxygen. The electron swarm parameters are calculated by using Monte Carlo simulation. The results show that there are relatively more electrons distributing in the high-energy range for the decreasing field than the local field, while less for the increasing field, compared with the uniform field. The effective ionization coefficients for the decreasing field are larger than the equilibrium values, and vice versa for the increasing field. The different behavior of the electron swarms in increasing and/or decreasing field is considered to be the reason of the dependence of the discharge current and the corona inception voltage on the electrode polarity during the surface discharge.