ELECTRIC-DISCHARGE EXCITATION OF THALLIUM IN HIGH-PRESSURE XENON

We report data obtained in pulsed 1.5-280-MW/l electric discharges in thallium-doped xenon gas at thallium densities of (1.5-26) ×10 15 cm-3 and xenon densities of (1-4) ×10 19 cm-3. Stable steady-state discharges were obtained without the use of preionization or sustainers. Steady-state E/N, J/N, and Tl and Xe excited-state populations were determined for the positive column of the discharge. These measurements indicate an electron temperature of 0.45-0.65 eV, with the gas temperature remaining at ∼0.1 eV during the several-microsecond discharges. The thallium states lower in energy than Tl(8S1/2) generally show a higher excitation temperature than the states from Tl(8S 1/2) to the thallium ionization limit, particularly at the higher current densities. The homogeneity of a 9-cm-long transverse discharge and the effects of this discharge on a laser beam propagating through the thallium-xenon medium were investigated. The implications of these results for a discharge-pumped Tl-Xe excimer laser are discussed.