An expirimental system for the measurement of vacuum UV below 115 nm from pulsed plasma in an N2/O2 environment

Summary form only given. Limited experimental literature exists for measuring radiation with wavelengths shorter than 115 nm primarily due to the difficulty associated with measuring VUV radiation due to the high absorption in molecular oxygen and optical materials. Furthermore, there is an increasing interest in quantifying the role of this radiation in the generation of low temperature plasmas. This paper describes a system for studying the early mechanisms of vacuum UV generation below 115 nm by inducing breakdown in an air environment near atmospheric pressure. However to avoid the attenuating effects of O₂, the experiment is set up such that the pressure drops to deep vacuum (i.e. ~10^-6 torr) within a distance of several millimeters from the location of breakdown without the use of a solid barrier. In order to perform this measurement, the experiment consists of an enclosure at high vacuum, a pair of electrodes, and a micro puff valve. The puff value releases an above atmospheric pressure wave of air in the vicinity of the electrodes, whose differential electrical potential is then raised to about 20kV with a rise-time on the order of 100 nanoseconds. With application of the pulsed electric field, the radiation emitted from the excited species escapes the very localized puff of air and propagates through the high vacuum largely unattenuated where it is resolved by vacuum UV-sensitive optics and detectors. With this setup, the generation of vacuum UV radiation below 115 nm can be studied in detail and in the future the data recorded with this system will be used in our modeling approaches for further understanding of low temperature plasma generation.