MICROWAVE RESONANT-CAVITY-PRODUCED AIR DISCHARGES

Air discharges produced in an Asmussen microwave cavity (0-300 W, 2.45 GHz, CW) between 0.5 and 100 torr were investigated. Gas temperatures (1000-2500 K) were estimated from rotational temperatures obtained from optical emission spectroscopy (OES). These agreed with a simple model of the heat transfer of the gas where Joule heating was included as the source term. Vibrational temperatures (3700-7300 K) were also determined from OES and followed the electron energy trends. Electron density (10(11)-10(13) cm-3), collisional frequency (10(11)-10(12) s-1), and plasma conductivity (0.08-0.3 (OMEGA-m)-1) were calculated from a self-consistent electromagnetic model of the cavity where the plasma was assumed to be a lossy dielectric. Absorbed power, electric, and optical probe measurements were used as the input parameters to the model.