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A detailed nonstationary kinetic model of a gas-discharge He-Ar-N{sub 2} laser on transitions of the second positive C({sup 3{Pi}}{sub u})-B({sup 3{Pi}}{sub g}) system of nitrogen is constructed. The main parameters of the laser are optimised for the three UV laser lines at 358, 381, and 406 nm. (lasers)

Correlation properties of light beams upon self-phase modulation in a thin layer of a medium with thermal nonlinearity are studied. It is found out that the efficiency of spatial coherence transformation of radiation is determined by the ratio of the characteristic coherence radius of the initial radiation to the size of phase inhomogeneities induced in the nonlinear medium.

The results of complete numerical optimisation of an electron-beam-pumped Xe laser emitting at 1.73, 2.03, 2.65, 2.63, 3.37, and 3.51 μm are presented. At all these wavelengths, the best output parameters are achieved in the Ar—Xe mixture. The maximum lasing efficiency (4.5 %) and the highest specific energy output (19 J L-1) are obtained at a wavelength of 1.73 μm. For wavelengths 2.03, 2.65, 2.63, 3.37, and 3.51 μm, the maximum efficiencies were 2 %, 1.7 %, 1.2 %, 0.6 % and 0.48 %, respectively. These maximum values of output characteristics in the Ar—Xe mixture can be obtained in a certain range of operating parameters.

The outlook for using narrow-band spontaneous emission sources for purification of smoke gases from sulphur and nitrogen oxides is demonstrated by calculations based on a nonstationary kinetic model of the N{sub 2} - O{sub 2} - H{sub 2}O - CO{sub 2} - SO{sub 2} mixture. The dependences of the mixture purification efficiency on the UV source power at different wavelengths, the exposure time, and the mixture temperature are calculated. It is shown that the radiation sources proposed in the paper will provide better purification of waste gases in the atmosphere. The most promising is a KrCl* lamp emitting an average power of no less than 100 W at 222 nm. (laser applications and other topics in quantum electronics)

The destruction of the spatial coherence of multimode laser radiation in a delay-line-based system is analysed theoretically and experimentally. A scheme of a coherence-transforming device operating in a broad wavelength range and various lasing regimes is proposed. This scheme is shown to be efficient for rapid speckle-noise suppression in optical recording and lithography.

A detailed nonstationary model of a He — Ar laser pumped by a hard ioniser is developed. It is found by numerical simulation that the pumping of the upper laser level is governed either by the three-body recombination of atomic argon ions with electrons or the dissociative recombination of molecular argon ions with electrons, depending on the argon content in a gas mixture. The conversion of dimer molecular argon ions into trimers, the quenching of the upper laser level by neutral atoms, and the spectral line broadening determine the optimum lasing conditions for the total mixture pressure and the partial argon pressure for different excitation conditions. The model adequately describes experiments using electron beam and nuclear pumping. The optimisation of a 1.79-μm nuclear-pumped He — Ar laser in the VIR-2M reactor gave a maximum laser efficiency of 1.2 %.

A description is given of a detailed nonsteady-state multiwave kinetic model of a laser, based on xenon atom transitions with λ = 1.73, 7.03, 2.65, 2.63, 3.37, and 3.51 μm in an He — Ar — Xe mixture pumped by a hard ioniser. The proposed kinetic model is tested against the results of experiments on electron-beam pumping of an Xe laser containing pure xenon, as well as binary and ternary mixtures. Numerical modelling is used to identify the main mechanisms pumping the upper active levels: three-particle recombination of atomic Xe+ ions (He — Xe mixture), dissociative recombination of molecular Xe2+ ions (pure Xe), dissociative recombination of molecular ArXe+ ions and electron excitation from the 6s' xenon atom states in an (He) — Ar — Xe mixture. It is shown that the contribution of each of the mechanisms to pumping of the upper active level is determined by the composition and pressure of the mixture.

A kinetic model of the active medium is developed for a nuclear-pumped laser (with an He — Cd — CCl4 mixture) based on transitions in the cadmium ion and atom. The results of numerical modelling give the distribution of the relaxation flux between excited states of the cadmium atom. A study is reported of the mechanisms responsible for the influence of the addition of carbon tetrachloride on the evolution of relaxation processes in an He — Cd plasma and on stimulated emission of the λ = 325.0 nm line. It is shown that the main factor hindering lasing as a result of the 4d9 5s2 2D3/2 → 4d10 5p 2P1/2 transition is the parasitic absorption of the stimulated radiation by metastable cadmium atoms.

A detailed transient kinetic model is developed for a laser with nuclear pumping of transitions in the oxygen atom (λ = 2.65 and 2.76 μm) in He — Ne — O2 — N2 — H2 — (CO, NO) mixtures. Numerical simulation is used to show that the main pumping mechanisms of the upper active levels are three-body recombination of atomic oxygen ions with electrons and the transfer of excitation, accompanied by oxygen dissociation, from metastable helium atoms to oxygen. The optimal lasing conditions and the ultimate output characteristics of the laser are found. The calculated results are in satisfactory agreement with experimental data.

The first detailed time-dependent kinetic model of a nuclear-pumped laser is developed for transitions in carbon and nitrogen atoms present in Ne?Ar? N2?CO? H2? O2 mixtures. Numerical simulation is used to show that the main mechanism of pumping the upper active levels of carbon and nitrogen atoms in Ne?CO? N2 mixtures is three-body recombination of atomic carbon and nitrogen ions. Dissociative recombination of an ArC+ ion becomes the main pumping channel when argon is added to a mixture. The optimal conditions and the ultimate laser output characteristics are identified. The calculated results are in satisfactory agreement with experimental data.

A brief historical review is followed by an account of the main results of many years of experimental and theoretical investigations of the problem of direct conversion of the nuclear energy into coherent radiation (nuclear-pumped lasers) and of constructing a reactor-laser. The main difficulties encountered in solving this problem and ways of overcoming them are discussed.

A transient self-consistent kinetic model is developed of an Xe — Sr — H2 laser emitting as a result of the 6s2S→5p2P3/2 (λ = 430.5 nm) transition in the strontium ion when pumped by hard ionising radiation. The optimal lasing conditions are found under which the efficiency of the active medium, in terms of the deposited energy, may exceed 3%. It is shown that efficient lasing is possible when the laser is pumped by electrons from a RADAN-type accelerator.

The ultimate efficiency of a Penning neon plasma laser (λ = 585.3 nm) is shown to be less than 0.5%, relative to the energy deposited in the active medium. The optimal conditions are found for pumping by external sources acting for various durations and the threshold value of the specific input power delivered by nuclear pumping is calculated.

A kinetic model of an He—Ne—Ar—H2 laser (λ = 585.3 nm) is developed taking into account the influence of nitrogen impurities. Small amounts of molecular nitrogen, at the level of traces in nominally pure gases, can have a significant influence on the output characteristics of the laser. It is shown that introduction of small amounts of hydrogen can lead to an improvement in the lasing characteristics when the pump power is increased.

A theoretical investigation was made of the dependences of the output energy, efficiency, gain, and optimal concentrations of the reagents on the pump duration and power near the threshold of an XeF (B → X ) laser. It was assumed that an Ne—Xe—NF3 mixture was pumped by a hard ioniser (nuclear radiation, electron beams, etc.). A study was also made of the influence of parasitic absorption on the energy characteristics of this laser.

This paper reviews theoretical and experimental investigations of the active media of high-pressure lasers with active media consisting of mixtures of inert gases and the vapor of group-II metals. The active media are pumped by hard ionizing agents: electron or ion beams or charged products of nuclear reactions (nuclear pumping). The physical origins of limitations on the laser power and efficiency of these active media with respect to injected energy are investigated. Detailed time-varying kinetic models are used under conditions of electron-beam and nuclear pumping to find the optimal conditions for lasing, along with the theoretical maximum output characteristics of high-pressure lasers operating on transitions of singly ionized metal atoms. The prospects for developing pulsed lasers using nuclear pumping are discussed.

A numerical simulation is used to show that new experimental data on the rate constants of xenon atoms in metastable and resonant states lead to a revision of the existing views on the mechanism of excitation of the upper active levels of a laser operating on IR transitions in xenon.

Experimental and theoretical investigations were made of an XeF laser pumped by a travelling ionising wave originating from a nuclear explosion. The results indicated that an efficiency, in terms of the input energy, could reach 1–3%.