Penning ionization of cesium by photoexcited mercury. Radiation transport effects

Summary form only given. Following our model of a photoexcited Hg-Cs-N/sub 2/-He system previously presented, we are now focusing attention on the radiative effects that control the spatial distribution of plasma and the overall system efficiency. Radiation trapping in mercury vapor at 253.7 nm is significant and frequently presents a great obstacle to excite the bulk of the vapor. It is strongly affected by spectral broadening of both the excitation light source as well as the medium being pumped. In the present case, much of the problem can be overcome by using both isotopically-enriched mercury source lamps and plasma medium. Pressure broadening in the plasma cell causes the effective radiative decay rate to be decreased from the rate for an isolated atom and it also increases the transmission probability for resonant photons to propagate into the medium. Both of these effects are desirable in the present situation.