Two-temperature modelling of pulsed high pressure caesium radiative discharge with recombination mechanism of light emission

A two-temperature model of pulsed high pressure caesium (HPC) discharge is developed on the basis of the radiative many component gas dynamic equations. The time-dependent radial distributions of the temperatures, concentrations and radial velocities of motion are determined for all plasma components. Peculiarities of plasma heating in the discharge are considered. It is shown that the main mechanism of the heat exchange in HPC discharge is intensive nonlocal radiative heat transfer. The spectrum of radiation, emitted from discharge plasma, is investigated. It is shown that, in the dense discharge plasma, a lowering of the ionization potential of an atom and the merging of the highest terms of spectral series (because of their broadening) result in a significant shift of the thresholds of recombination 6P and 5D continua. It explains the formation of an almost continuous spectrum of the discharge emission in the visible range. Luminous characteristics of the discharge are calculated. The luminous efficacy eta = 90 lm W(-1) and a colour rendering index R(a) = 98 are obtained. The study shows that the pulsed HPC discharge is an effective mercury-free light source with recombination mechanism of emission.