Sharp rise of excitation temperature in the periphery of lamp arcs measured from the 254 nm resonance line of mercury

Abstract

Unexpected sharp rise of the excitation temperature of the resonance state of mercury measured in the arc boundary of a high intensity discharge lamp verifies the existence of an enhanced radiation source in the outer arc layer from which radiation excess observed in the valley of self-reversed lines is originated. This temperature was deduced from line-of-sight measurements of the radiance at the red peak of the 254 nm resonance line of mercury. The nonradiative transfer of excitation energy by resonant collisions between mercury atoms in the dense plasma medium is a very plausible explanation of the radiation source enhancement.