Anomalous electron decay in nanosecond repetitively pulsed discharges

Nanosecond pulsed discharges (ns-discharges) have recently been proven valuable over a wide range of applications in the fields of combustion, aerodynamics, medicine, and many others. A comprehensive study of the properties of ns-discharges including dynamics of plasma generation and subsequent decay is critical for tailoring the plasma to a particular application.

In this work, coherent microwave scattering is used to study electron decay in the single-pulse and nanosecond repetitively pulsed discharges in a pin-to-pin configuration in atmospheric air. Measurements indicate that the electron decay times are substantially longer (1–2 orders of magnitude) than that which can be explained by attachment and dissociative recombination mechanisms using the reaction rates available in the literature. The observed discrepancy can be potentially attributed to an inapplicability of the rate coefficients available in the literature for conditions of ns-discharges and to additional ionization of gas after ns-pulse in collisions of electrons with excited gaseous species.