Characteristics overvoltage nanosecond discharges on mixtures of helium and argon with admixtures of water vapor


Introduction. Nanosecond overvoltage discharges in high-pressure gases between metal electrodes are promising for applications in selective "point" UV-VUV lamps. The most investigated working media of such lamps are vapors of copper and iron in atmospheric pressure air. The use of electrodes with a lower melting point and a transition to a gaseous state, for example, zinc in a medium of high-pressure inert gases has been little studied, which hampers the understanding of the physics of processes in these lamps and the optimization of their output characteristics.
Purpose. The aim of this work is to study the characteristics of an overstressed nanosecond discharge between electrodes from zinc in high pressure helium and argon that can be used to develop selective point lamps in the spectral range of 200-215 nm.
Methods.The optical-spectroscopic method of investigation of discharge plasma with high time separation is used in this work.
Results. Optical-spectroscopic method with high temporal resolution is used in this work for investigation of the discharge plasma. As a result of the study of the optical characteristics of an overstressed nanosecond discharge in helium and argon (at pressures p = 7-220 kPa) with a distance between zinc electrodes of 1 mm it was found that it is a source of UV radiation of zinc atoms and ions in the spectral range of 200-215 nm. The peak value of the electric power of the discharge is ~ 1-2 MW, and the energy deposition to the plasma per pulse is ~ 60-80 mJ. At adding small amount of water vapor impurities to inert gases, intense spectral lines of the hydrogen atom were recorded in the plasma emission spectra; the H lines can be used to estimate the plasma parameters.
Conclusion. The experiments revealed the suitability of this discharge for use in a selective "point" UV lamp operating on zinc vapors

Keywords: high-voltage nanosecond discharge, zinc, helium, argon, water vapor, emission spectrum, ultraviolet