Numerical Simulations of Air Breakdown by Microwave With Two Orthogonal Electric Fields

In the near-field zone of an antenna or a microwave device, high-power microwave that may contain two orthogonal electric field components frequently causes air breakdown. The electric field power of microwave for heating electrons is deduced from the equation of electron momentum, and is introduced into a model coupling the equations of electron number density and electron energy to investigate air breakdown. Breakdown prediction obtained from the model considerably matches with that of the particle-in-cell Monte Carlo collision model. The amplitude of the mean electron energy changes periodically with the phase difference between the two electric field components with the same amplitude. At a high air pressure, breakdown formation time depends strongly on phase difference, but this dependence decreases as air pressure decreases. The dependence of air breakdown on the amplitude difference between the two electric field components is also unveiled under a fixed electric filed power. The approximate analytical solution of the mean electron energy is presented to analyze our numerical results.