Electron and Negative Ion Production Rates in Air Plasmas with Ionizing Radiation

Electron and negative ion production rates during atmospheric discharges in the presence of ionizing radiation are investigated. Ionizing radiation creates free electrons and negative ions with number densities that may be orders of magnitude higher than background conditions. These high densities not only facilitate air breakdown between high-voltage electrodes or at the focal point of high-power electromagnetic beams, but also change the breakdown evolution and the neutrals recombination history after the power source is turned off. Time dependencies of breakdown and recombination rates on radiation levels and aerosol concentrations, are modeled and compared to measurements of breakdown between electrodes. This research is part of a wider effort to investigate the feasibility of a remote detection scheme for radioactive materials, utilizing sub-THz beams to produce air breakdown [G. S. Nusinovich, et al. J. Appl. Phys. \textbf{109}, 083303 (2011)].