The atomic xenon laser operates on seven infrared transitions (1.73–3.51 μm) between the 5d and 6p manifolds. Intrinsic laser power efficiencies exceeding 5% have been previously obtained in Ar/Xe mixtures, principally at 1.73 μm (5d[3/2]1→6p[5/2]2). The kinetic mechanisms responsible for this performance, though, are not well understood. In this paper, we report on a computer model for the electron-beam-pumped xenon laser in Ar/Xe mixtures with which we have investigated some of these excitation mechanisms. Based on the results of a parametric study of power deposition (50 W cm−3 to 100 kW cm−3), gas pressure (0.5–6 atm), and xenon fraction, we suggest that the high efficiency obtained in Ar/Xe mixtures is due to rapid collisional cascade to the upper laser level of the 1.73-μm transition following dissociative recombination of ArXe+ and selective quenching of the lower laser level of the 1.73-μm transition by collisions with argon. The results of our model indicate that the decrease in laser performance at high Xe fractions results from electron-impact excitation of the lower laser levels (6s→6p) and quenching of the 5d manifold by collisions with atomic xenon. The degradation of laser performance at high specific power deposition is most likely due to electron-collision mixing of the 5d and 6p manifolds. As a result of the lower levels being cleared dominantly by atomic collisions, we predict that optimum performance is then obtained at higher gas pressures when increasing power deposition. The results of the model predict that optimum power deposition is obtained when the fractional ionization is ≊2–3×10−6.

The transport of electrons through a background nitrogen gas under the influence of a spatially varying electric field is studied through a Monte Carlo simulation. Nonhydrodynamic effects, i.e., a nonlocal dependence of the electron transport and rate coefficients on the ratio of the field strength to the neutral density, E/N, are observed. For example, the high-energy tail of the electron-energy distribution function is sluggish in responding to the spatially varying field, and hence the ionization coefficient lags the local field value. In addition, the spatially dependent vibrational-excitation-rate coefficient goes well beyond the range of values found in hydrodynamic calculations. The results are discussed in terms of recent formulations of nonhydrodynamic transport theory and are contrasted with previous results.

A practical difficulty in Monte Carlo simulations of electron transport occurs when the electron number density changes significantly over the time or length scale of the simulation. In this letter, we present a simple scaling procedure to resolve this difficulty that is easy to implement and that is exact for linear collision operators. A simulation of electron transport in nitrogen at high electric field strength is included to illustrate this rescaling procedure.

Excimer lasers excited by electron or ion beams having energy deposition of 100’s J/ℓ over many microseconds experience a temperature rise of hundreds of degrees (K). The increase in gas temperature may greatly impact both the kinetics and spectroscopic parameters. In this letter we discuss the high-temperature (≤900 K) plasma kinetics and absorption in He and Ne buffered gas mixtures for particle beam pumped XeF lasers. We find both gain and absorption depend differently on gas temperature in these mixtures (absorption decreasing in He mixtures, increasing in Ne mixtures). The differences are attributed to a reduction in diatomic absorbing species with increasing temperature and differences in the temperature dependence of the optical absorption cross sections for NeXe+ and Xe+2.

A theoretical analysis of the cathode fall experiments of Doughty and co-workers I Phys. Lett. A 103, 41 (1984); Apple Phys. Lett. 46, 352 (1985) J is presented, based on a Monte Carlo simulation of the electrons in the discharge. The nonlocal aspects of the electron kinetics (i.e., the average energy and the ionization coefficient) are emphasized and the connection is made with the work of Davies and Evans [J. Phys. D 13, L 161 (1980)]. Further examples of the electron kinetics are the light output in the negative glow and the electron energy distribution at the anode. The ion kinetics concentrate on the ion drift velocity and the molecular ion (Ne2~ ) formation.