A flat glow discharge excimer radiation source

Increasing the current of a microhollow cathode discharge in high-pressure xenon allowed us to generate disc-shaped 100- to 150-/spl mu/m-thick plasma layers on the planar cathode of a microhollow electrode system, with diameters approaching 1 cm. The plasma layer has been found to emit intense excimer radiation at 172 nm. The maximum of the excimer emission shifts with increased current toward the perimeter of the plasma disc, and the spectral distribution in the area close to the cathode hole changes from vacuum ultraviolet to visible. Plasma filaments, radiating in the visible, are formed which extend from the center to the perimeter of the disc shaped plasma. They correspond to areas of reduced excimer emission, indicating a transition from nonthermal to thermal plasma.