Theoretical kinetics with one-dimensional fluid model and experimental investigation on coaxial XeCl excilamps

This paper presents a one-dimensional homogenous model of high power-density XeCl excilamp pumped by dielectric barrier discharge (DBD) with larger discharge gap and lower Cl 2 density in Xe/Cl 2 mixture, to research the electrical and chemical discharge characteristics leading to the production of XeCl* molecules for the optimal discharge parameters. The peaked wavelength 308 nm from the emission band of XeCl* exciplex molecules, show great promise as photochemotherapy for biomedicine applications. The temporal evolutions of the plasma voltage, current density and the species densities have been analyzed. The model validity has been checked by comparing with the experimental results. It is shown that the XeCl excilamp is a capacitive discharge during the entire voltage cycle and the accumulation of charge deposited in the dielectric surfaces play an extreme role in promoting the extinction of this discharge and the generation of next discharge. The UV radiant efficiency of the DBD XeCl excilamp depends on effect of the discharge behavior on the amplitude of the applied voltage, the total gas pressure, and the Cl2 density. XeCl excilamp has an optimized pressure around 150 mbar with the maximum radiant efficiency of 8.5% for 308 nm from XeCl* molecules and 1.3% for 172 nm from Xe 2 * molecules. According to the corrected simulation, the radiant efficiency of the optimum pressure is 6.0% for XeCl*molecules. Cl2 density in DBD-based XeCl excilamp strongly influence the balance of electron production and loss due to the dominant dissociative attachment process of electrons to Cl 2 molecules, which have significant dependence on the UV light output efficiency. It is demonstrated that the highest XeCl* density occurs near the dielectric during the current pulse. Therefore, electrical and radiant characteristics of XeCl excilamps can be considered as the basis to design the high power-density exciplex lamps in practical applications.