Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

The authors have developed a new method of applying the microwave cavity perturbation technique that allows one to measure simultaneously real and imaginary conductivity decays. They report here results of afterglow decay measurements for air and N 2 excited by an intense e-beam pulse. From these data, they calculate electron densities and electron temperatures using exact expressions for the conductivities. The electron density decays for laboratory and synthetic air are approximately 10 and 40 times longer than predicted based on electron attachment for humid and dry air, respectively. Ambipolar diffusion coefficients and dissociative recombination rates measured at low pressures are inconsistent with previous results because the deduced electron temperatures are much higher than values used in previous studies. The decays in humid air appear to be dominated by ion conductivity.