Performance Enhancement of a Dielectric Barrier Discharge Vacuum-Ultraviolet Photon Source Using Short-Pulsed Electrical Excitation

We have studied the electrical and optical characteristics of an air-cooled argon excimer vacuum-ultraviolet lamp (λ ~ 126 nm) excited by a dielectric barrier discharge powered by: 1) pulsed or 2) sinusoidal high-voltage drivers from 32 to 100 kHz. Compared to sinusoidal excitation, pulsed excitation gives nearly ~ 2x higher vacuum-ultraviolet (VUV) output and electrical-to-VUV conversion efficiency at high pressure (800-900 mbar). Visually, the pulse-driven plasma is spatially homogeneous, whereas for sinusoidal excitation the plasma becomes filamentary at higher pressure and/or frequency. Spectral emission is highly monochromatic with most of the output in the desired VUV band (λ = 115-140 nm). With the lamp running at pressure >700 mbar and power loadings >1.6 W/cm3, a sharp spike in VUV output was consistently seen at turn-on. We believe that transient phenomena or favorable initial conditions may be partly responsible for this VUV spike, although the equilibrium VUV output appears to be limited due to thermal dissipation, gas heating, and associated loss of gas from the active region. We propose that we may be observing the same intrinsic VUV spiking phenomena as reported in liquid nitrogen-cooled Xe, Kr, and Ar excimer lamps by Gerasimov et al. More importantly, we believe ours is the first such observation reported for an excimer VUV lamp operating near room temperature. This VUV spiking behavior raises the prospect that designs with improved thermal management may achieve even higher VUV power and efficiency.