Microwave Absorption And Optical Emission Spectrometry Analyses Of Ambient Air Plasmas Induced By Pulsed Electron Beams

This work is devoted to the characterization of plasmas produced by an intense pulsed relativistic electron beam propagating in air at atmospheric pressure. A large range of a time integrated dose is investigated [0.75 to 7.4] kGy(air) inducing electron densities from 2x10(12) up to 1.6x10(14)cm(-3). The air plasmas are analyzed by two complementary diagnostics: microwave absorption and optical emission spectroscopy, to deduce plasma parameters during the creation and relaxation phases, respectively. A reduced air kinetics model is used to calculate transmission measurements during the electron beam pulse and to infer electric conductivities, which are compared to the results of three-dimensional Maxwell calculations. Optical emission spectra are measured and compared to calculated ones, giving rotational and vibrational temperatures during the relaxation phase of the plasma. These plasma characterizations may be used to model non-equilibrium atmospheric air plasma chemistry in the framework of, for instance, streamer dynamics as well as corona or dielectric barrier discharges.