Optical characteristics and plasma parameters of a blue-green exciplex lamp

Abstract

The optical characteristics and plasma parameters of an exciplex lamp radiating in the blue-green spectral range are studied. A plasma is generated by an atmospheric-pressure barrier discharge initiated in a quaternary mixture including mercury dibromide, sulfur hexafluoride, nitrogen, and helium. It is shown that the exciplex lamp can radiate at an elevated repetition rate of pump pulses (1–12 kHz) under the conditions of mixture self-heating. A tradeoff between the radiation power and nitrogen partial pressure is found. The mean specific radiation power in the blue-green range at a level of 480 mW/cm3 is achieved at partial vapor pressures of mercury dibromide, sulfur hexafluoride, nitrogen, and helium of 0.70, 0.07, 4.00, and 117.20 kPa, respectively. The plasma parameters, namely, the electron energy distribution function; concentration, temperature, and mean energy of electrons; transport properties; and rate constants of elastic and inelastic electron scattering by the working mixture components are determined as functions of ratio E/N (where E is the electric field strength and N is the total concentration of mercury dibromide, sulfur hexafluoride, and nitrogen molecules and helium atoms). It is found that mercury monobromide molecules and also excited and higher energy states take part in the population of exciplex molecules HgBr* (B2Σ12/+ states) in the course of quenching these exciplexes by sulfur hexafluoride and nitrogen molecules.