Dielectric window breakdown in oxygen gas: from vacuum multipactor to collisional microwave discharge

The major limiting factor in the transmission of high power microwave is dielectric window breakdown. Using a PIC/MCC model, dielectric window breakdown from vacuum multipactor to collisional microwave discharge in noble gases has been investigated [1]. In contrast with noble gases, however, the oxygen in air produces negative ions, which can reach five or more times the electron density with a strong impact on the breakdown. In this work, breakdown of a dielectric window in contact with oxygen gas is investigated over a wide pressure range, and extension of the theoretical scaling law for breakdown in noble gases [2] is sought for oxygen and air. \newline \newline [1] H.C. Kim \textit{et al}., \textit{Phys. Plasmas} \textbf{13}, 123506 (2006). \newline [2] Y.Y. Lau \textit{et al}., \textit{Appl. Phys. Lett.} \textbf{89}, 261501 (2006).