Interaction of Intense rf Fields with Heated Air

A model is formulated which predicts the characteristics of a short duration, intense microwave pulse propagating in initially heated, high-temperature air. The temporal and spatial evolution of the electron temperature and density throughout the plasma are specified upon incorporating certain kinetic processes involving N2, NO, and O for 4000°–5000°K air. In conjunction with measurements, field-induced ionization rates of initially heated 4500°K air are presented and found to be substantially greater than room temperature-to-4000°K ionization rates. The post breakdown recombination rate has also been found. The usual constant collision frequency assumption used in predicting rf breakdown levels is shown to be a good approximation.