Production and characterization of high-pressure microwave glow discharge in a microgap aiming at VUV light source

Using microwave excitation, a high-pressure (similar to 1 atm), high-density (similar to 10(15) cm(-3)), non-equilibrium plasma is produced continuously in the 100-mu m-microgap between two knife-edge electrodes at a power deposition level of similar to 1 MW/cm(3). In discharges using Ar-2 and Xe-2 vacuum ultraviolet emission due to Ar-2 and Xe-2 excimers has been confirmed. To obtain plasma with a gas temperature as low as possible for efficient production of excimer molecules, the gas temperature characteristics of the microgap discharge was studied in detail for air and He/N-2 discharges. The results indicate that the gas temperature is rather insensitive to the gas flow even if the flow is rapid enough to affect the diffusive heat conduction in the plasma. This appears to suggest the existence of a rapid heat transport mechanism other than diffusive heat conduction in the microgap plasma. (c) 2005 Elsevier B.V. All rights reserved.