A Hybrid Model to Predict Electron and Ion Distributions in Entire Interelectrode Space of a Negative Corona Discharge

Atmospheric direct current (dc) corona discharge from thin wires or sharp needles has been widely used as an ion source in many devices such as photocopiers, laser printers, and electronic air cleaners. Existing numerical models to predict the electron distribution in the corona plasma are based on charge continuity equations and the simplified Boltzmann equation. In this paper, negative dc corona discharges produced from a thin wire in dry air are modeled using a hybrid model of modified particle-in-cell plus Monte Carlo collision (PIC-MCC) and a continuum approach. The PIC-MCC model predicts densities of charge carriers and electron kinetic energy distributions in the plasma region, while the continuum model predicts the densities of charge carriers in the unipolar ion region. Results from the hybrid model are compared with those from prior continuum models. Superior to the prior continuum model, the hybrid model is able to predict the voltage-current curve of corona discharges. The PIC-MCC simulation results also suggest the validity of the local approximation used to solve the Boltzmann equation in the prior continuum model.