Electron density measurements in afterglow of high power pulsed microwave discharge

In this paper, we present experimental results of diagnostics of a high power microwave pulsed discharge (100 kW at 9 GHz, 2.5 µs) in nitrogen and oxygen gases. We used microwave interferometers operating at 15 and 35 GHz equipped with dielectric rod antennae. The operating pressure was between 20 and 2000 Pa. In nitrogen the large value of the recombination coefficient α r = (1–2) × 10 −6 cm 3 s −1 suggests that (α r = 2 × 10 −7 cm 3 s −1 ) ions coexist with the predominant complex ions, and , at pressures greater than 700 Pa. In oxygen the value of the recombination coefficient increases with increasing pressure from a value typical of (α r = 3 × 10 −7 cm 3 s −1 ) at a pressure of 200 Pa to a value of α r = (2–4) × 10 −6 cm 3 s −1 at pressures above 1000 Pa as a consequence of the formation of at higher pressures.