High-efficiency performance characteristics of a new microwave discharge-pumped excimer lamp

Abstract

Long-pulse quasi-continuous microwave discharge-pumped excimer lamps have been developed as UV light sources for photochemistry. Optimal operating conditions for a lamp with high efficiency and high average power output have been investigated. The experimental setup used in this study consists of a 245-GHz magnetron tube with a modulator, directional couplers, a tuner, and a resonant cavity with a quartz discharge sphere. The microwaves enter a cylindrical cavity made of metallic mesh, where they create a strong electromagnetic field of TE/sub 111/ mode, causing the excimer lamp gas mixture in the sphere to discharge and emit UV light with a narrow spectrum. Using quasi-continuous microwaves, a KrF average fluorescence power of 53 W was obtained with an intrinsic efficiency of 8.3% for 678-W microwave average power deposition. A KrF fluorescence peak power of 120 W was obtained with a power efficiency of 12.1%. When long-pulsed (1-9 mu s FWHM) microwaves were used, a KrF fluorescence average power of 43 W was obtained with an intrinsic efficiency of 12.5% for 341-W microwave average power deposition. >