Spectral Line Competition in a Coaxial Electron-Beam- Pumped High Pressure Ar/Xe Laser

In order to study the kinetic mechanism of the e-beam pumped Ar/Xe laser, the temporal profiles of individual laser lines during multiline oscillation have been measured as a function of power deposition (1-12MW/cm 3) and gas laser pressure (2-14bar) using a short pulse (30 ns) coaxial electron beam as excitation source. It was found that the optimum output energy at each pressure was obtained at the same specific power deposition. Strong line competition has been observed between the 2.65 and 1.73 ~tm transitions. In order to explain our results we suggest that besides electron collision mixing (ECM) between the 5d and 6p levels of Xe, there is also a redistribution between all 6p levels which strongly favours the lower levels at higher pumping densities. PACS: 34.80 D, 41.80 Dd, 42.55 F The atomic xenon infrared laser has attracted the attention of researchers since an electrical effÉciency of nearly 1% was reported for this laser by Newman and DeTemple using an electron beam preionized discharge [1]. The atomic xenon laser operates on six infrared transitions (1.73 ~tm-3.51 gm) between the 5d and 6p manifold (Fig. 1). An intrinsic efficiency of about 5% with a maximum specific output energy of 8 J/liter was reported in 1985 by Basov et al. [2]. Recently is was observed that an e-beam sustained system has the potential of about 9% intrinsic efficiency [3]. The laser operates in various modes such as an electric discharge mode [4, 5], with electron-beam excitation [6,7], with an electron beam sustained discharge [2, 3, 8], fission fragment excited [9], and in a microwave discarge [10]. Power depositions of 10W/cm 3 • bar to 1 MW/cm 3 " bar, pumping pulse durations of 10ns-5 ms, and total gas pressures of 0.5-14bar in a mixture consisting of 0.01-10% of xenon in rare gas buffers (He, Ne, Ar, Kr) have been investigated. Since the most promising laser performance has been obtained in Ar/Xe mixtures with electron-beam pumping and electron-beam sustained discharge pumping, most experimental work has been carried out on those systems. Recently there has been increased interest in studying the kinetic mechanism [11]. As the atomic xenon laser * Permanent address: Institute of Electronics, Academia Sinica, Beijing, RR. China is a highly complicated laser system, little is understood about the fundamental kinetic mechanism which is responsible for the performance of the laser. In order to study the kinetic processes of the Ar/Xe laser, we have operated the laser with a short pulse table-top coaxial electron beam source. Measurements of the delay times of the various laser lines with respect to the pumping pulse as a function of different total gas pressures and power deposition rates have already been made [12]. In this paper the temporal profiles of the individual laser lines have been studied in a large parameter space. The results of these measurements will be presented and discussed with respect to the line competition. We found