Spectroscopic studies of emissions from microhollow cathode discharges

Abstract

Summary form only given. Conventional hollow cathode discharges are typically operated at pressures ranging from mTorr to Torr. Operation at higher pressures (up to atmospheric pressure) is possible, if the hole diameter is reduced to dimensions of about 100 /spl mu/m with a corresponding reduction in the cathode-anode gap (microhollow cathode discharge). A microhollow cathode discharge (MHCD) operated at high (atmospheric) pressure is a simple, compact, and efficient sources of radiation such as rare gas excimer emissions. The conditions in a MHCD satisfy the two criteria necessary for excimer formation, (i) a sufficiently large number of energetic electrons and (ii) pressures high enough that three-body collisions occur with sufficient frequency. We have started a series of spectroscopic studies of emissions from MHCDs in the rare gases Xe, Ar, and Ne as well as in molecular nitrogen and air aimed (i) at elucidating the basic collision and relaxation processes in a MHCD and (ii) at obtaining a rudimentary understanding of the electron, neutral and ion temperatures in MHCDs under various operating conditions (pressure, current, electrode geometry, and hole size).