The expected energetic performances are presented for amplification of short pulses (approximately 10^-12 s) either directly in chain pulsed chemical laser (PCL) active medium, or in active media created by optical pumping of resonantly absorbing molecules by radiation of PCL. The calculations were based on the data for PCL energetic and amplifying performances and also on the data for pumping of N₂O molecules by HF laser radiation, both being obtained by us earlier. For amplifying a short pulse in DF-CO₂ PCL active medium, the energy output of 6J/l is achievable, while 8 - 10 J/l is attainable for regenerative amplification in HF(DF) laser (50 J/l(DOT)atm - under free oscillation conditions for both). For regime of optical pumping, the energy of N₂O short-pulse radiation can make 10% of pump (PCL output) energy. A series of other promising three- and four-atomic molecules is considered. The comparison of various variants of embodying of superpowerful laser systems based of chain chemical lasers is carried out. The conception of construction of short- pulsed laser systems with radiation energy of up to 10⁴ J is submitted with the expectation of their using for creation of dense relativistic plasma, as new perspective object of researches, and for realization of laser fusion.

The results of experimental study and numerical modeling of the high-power photoinitiated pulsed chemical DF/HF lasers operating in modes of free-running and amplification in the cascade scheme 'master generator (MG)- amplifier (A)' are presented. The comparative analysis of the laser operation efficiency for these modes with the object of obtaining maximal energy characteristics and radiation brightness is carried out. The maximal specific energy of 40 - 50 J/l and the maximal total energy of 2.9 - 3.1 kJ at divergence of 10^-3 radian are obtained in free-running mode for DF- and HF-laser and values of 12 J/l and 290 J respectively are obtained at divergence of 8 X 10^-5 radian for HF-laser. In mode of MG - A it is obtained in experiment 37 - 42 J/l, 2.9 - 3.4 kJ. On the base of numerical simulation it is possible to make a forecast as 60 J/l, 10 - 20 kJ and 5 X 10^-5 radian with efficiency > 50%.

The main reasons, complicating increase of the laser energy and average output power in the wide-aperture electric- discharge lasers, operating in the repetition rate mode, are analyzed in the paper. Physical and technical requirements to the design of the laser chamber and pump source for obtaining of the high technical parameters are formulated. Lines of attack on the problem of creation wide-aperture laser consisting of separate sections, located along the active length, are proposed. A new design of electrode unit, in which each electrode is made of electrically insulated plates, connected to a common bus of the pump source through a separate stabilizing inductor, is the foundation of this arrangement. The results of the test of the new electrode unit in electric-discharge HF(DF)-chemical laser are presented. It is experimentally shown that at its use in the laser with active mixture, based on SF₆ and H₂(D₂), is formed a stable volume discharge at different interelectrode gaps (up to 12 cm). The maximum laser efficiency 3.5% for HF and 2.4% for DF at the specific output energy of 4.2 J/l and 2.9 J/l accordingly was obtained. The conception of the wide-aperture electric discharge laser creation with a large active volume, based on the cylindrical shells, is considered.

The most useful forms of plasma generation, including self- sustained and externally sustained classes, will be compared with respect to their physical characteristics, limitations, and specific applications for which each is best suited. Controlled avalanche discharge excitation will be emphasized, since it provides a way around foil window breakage limitations of te electron beam ionization technique, and hence it enables a further extension of lasers into extremely high average power and high repetition rate-high peak power regimes. However, special high voltage pulse forming techniques and plasma impedance matching designs are required. A few such circuits and methods will be presented. Finally, some specific applications that may be uniquely enabled by controlled avalanche ionization - including an electric discharge-based oxygen-iodine laser - will be presented.

This paper reports on the physics of a self-sustained volume discharge without preionization, self-initiated volume discharge (SIVD), in working mixtures of nonchain HF(DF) lasers. Dynamics of SIVD in discharge gaps of different geometry is thoroughly described. The mechanisms of restricting current density in a diffuse channel in electric discharges in SF₆ and SF₆ based mixtures determining the possibility of the existence of SIVD were suggested and analyzed using simple models. It is shown that the most probable mechanisms are the electron impact dissociation of SF₆ and other mixture components, electron-ion recombination and electron attachment to vibrationally excited SF₆ molecules. Starting from a comparison analysis of the rate coefficients of these processes, it was found that the electron-ion recombination is capable of compensating for electron detachment from negative ions by electron impact. It is established that SIVD can be observed not only in SF₆, but in other strongly electronegative gases, e.g., in C₃F₈ and C₃HCl₃. Analysis is given of the factors determining uniformity of active medium in nonchain HF(DF) lasers. Some special features of operating nonchain HF(DF) lasers with small, 2 divided by 6 cm, apertures are carefully examined and the results of measuring the nonchain HF(DF) laser divergence are presented. Consideration is given to the problem increasing the aperture and discharge volume of nonchain HF(DF) lasers and, based from the experimental results, the possibility is shown of increasing their energy to a level of approximately 1 kJ and above.

An efficient small scale TEA (Transversely Excited Atmospheric) CO₂ laser has been considered. The laser was a low flowing, UV preionized, pulsed system. Specific design of the head as well as the electrical circuit ensure the laser operation with high efficiency and reliability. Nonconventional CO₂/Y, Y equals N₂/H₂; H₂/He and H₂ gas mixtures showed relatively high energy output. CO₂/N₂/H₂ mixture as the most superior one produces output energy and peak power of 220 mJ and 1.40 MW, respectively. High-energy output of the laser was employed for surface modification of austenitic stainless steel AISI 316 and titanium nitride (TiN) coating deposited on the same steel substrate. Used laser peak power densities of 100 and 170 MW/cm² have induced the morphology changes of AISI 316 steel and TiN coating, respectively.

Influence of active medium non-uniformity of 300 ns pulse pump electric discharge XeCl laser on divergence of amplified radiation has been investigated. It was shown that in case of 100 - 200 kW/cm³ pump power the laser active media allows to amplify the diffraction limited laser beam practically without distortion. In case of 400 - 500 kW/cm³ pump power after 120 ns of discharge burning the micro- and macro-inhomogeneities appeared. These inhomogeneities increased the amplified radiation divergence. It was established that basic reason of a divergence degeneration was inhomogenity of gain profile in active medium. In our case amplification increased when the macro-inhomogeneities developed and the absorption increased when the micro- inhomogeneities developed in local regions of active medium.

First steps of development of an energetic (sub)nanosecond XeCl laser source are reported. For that purpose, a non- linear pulse shortening technique based on Stimulated Brillouin Scattering (SBS) is used for the temporal reshaping of an XeCl laser pump pulse. A compression factor of 10 has been demonstrated leading to the generation of a few nanosecond FWHM pulse duration pulses from a 65 mJ - 40 ns (FWHM) XeCl laser source. Further works are planned to improve the energy of the nanosecond Stokes pulse.

The results of an experimental investigation into lasing and spontaneous emission of the nitrogen laser excitated by a transversal volume discharge with inductive-capacitive stabilization are presented. The laser operated in the pulse repetition rate mode without gas flow. An average spontaneous emission and lasing power as functions of a pulse repetition rate for a number of charging voltage values of storage capacitors is presented. The radiation pulse stability for repetition rate up to approximately 500 Hz was investigated. In some regimes, the average lasing power rises linearly up to 120 Hz and spontaneous emission power up to 300 Hz. The specific lasing power per unit length of the active volume (along the optical axis) was > 1 mW/cm. The spontaneous emission power rising was linearly at specific pump power per unit area of the plasma layer surface up to 5 W/cm². It is shown that transverse volume discharge with inductive-capacitive stabilization allows creating enough effective lasers and lamps, operated without gas flow with the pulse repetition rate above 200 Hz. The strong laser beam deviation from the optical axis is found.

The present work reports development of simple, reliable, powerful pseudospark switches. Operating parameters of the switches and parameters of XeCl-lasers with pumping generators on the base of the switches are presented.

Formation of a diffraction limited divergence and obtaining a high contrast of radiation in electric-discharge XeCl laser system due to SBS are investigated. Possibility of a correction of laser beam wave-front distortion on an astigmatic and a spherical aberrations and on a refractive coefficient non-uniformity in optics elements and atmosphere is shown. Correction of laser beam wave-front having the 20- fold distortion of diffraction limited angle using phase- conjugate Brillouin mirror allowed to obtain the initial angle of 2 X 10^-5 rad divergence of laser beam. Use the threshold conditions of Brillouin scattering allowed to increase the XeCl laser radiation contrast from P_gen/P_noise approximately 4 up to P_gen/P_noise equals 10⁶ - 10⁷.

The data on optimization of output parameters (output energy and laser efficiency) and distribution of laser radiation energy on the output window cross-section of the wide- aperture Xe-laser pumped by a radially-convergent e-beam with pulse duration of approximately 0,5 microsecond(s) at the FWHM were obtained. It is shown experimentally, that the requirement of homogeneity of output laser radiation across the aperture limits the energy deposition value from below, and the requirement of maximal laser efficiency restricts the energy deposition value from above. In the experiment the maximal laser efficiency as 1,5 - 2% was obtained at the specific energy deposition of 12 - 14 mJ./cm³atm. The calculations show that with cleaning of the operating mixture from molecular gases impurities the laser efficiency and energy output can be increased in 1.5 - 2 times. The negative influence of impurity gases at optimum range of pumping power is decreasing of electron temperature and as a consequence decreasing of the upper laser level pumping.

Development of a long-pulse master oscillator with pulse duration of 300 ns (FWHM) is reported. The oscillator is made on the base of a long-pulse spark preionized XeCl-laser pumped by a self-sustained discharge using a double- discharge circuit. The pre-pulse is formed by a generator with an inductive energy storage and a semiconductor opening switch. The laser produces up to 1,5 J in pulse with total duration up to 450 ns.

Present paper reports the results of theoretical investigations of influence of Q-factor value of optical resonator on spatial properties and output characteristics of long pulse discharge pumped XeCl laser. It has been shown that high value of Q-factor do not influence homogeneity of discharge plasma. When the value of Q-factor is low an inhomogeneous distribution of intensity of laser photon flux occurs already at the beginning of generation. Photoionization of excited Xe atoms leads to an enhancement of electron density near the output mirror in comparison with the rest discharge volume. Further development of inhomogeneity is caused by instability of discharge plasma. Inhomogeneity of pumping discharge initiated by interaction between laser photon flux and discharge plasma leads to significant changes of characteristics of laser radiation.

Results of experimental and theoretical investigations of XeCl with discharge formation by means of inductive energy storage and semiconductor opening switch have been presented. Main pumping of active medium has been performed by capacitive energy storage. Measured laser output energy is 0.8 J Laser efficiency calculated from energy stored in capacitive energy storage is 2.3%. Simulations predict that the optimization of pumping conditions may increase these parameters in two times.

Effect of the border of preionization on discharge uniformity and quality of laser radiation is studied theoretically in the framework of 2D model of discharge pumped XeCl laser. Calculations show that near the border between preionized and unpreionized regions a local enhancement of the electric field occurs. This phenomenon is induced by a divergence of the X-ray beam. The local enhancement of the electric field promotes formation of cathode spots and, finally, leads to formation of discharge inhomogeneities. A decrease of sharpness of the border of preionization region reduces the local enhancement of electric field and improves characteristics of the laser radiation.

A mathematical model for pulse discharge CO lasers includes vibrational kinetics of CO and N₂ molecular species, Boltzmann equation for electron energy distribution and equations for laser generation. The effective method for numerical simulation of pulse CO lasers is proposed. Actually it is a splitting one with respect to physical processes.

Quasi two-dimensional (r,z) model of large bore copper vapor laser (CVL) was developed. Full set of heat and species (charged and neutral) transfer equations, Maxwell equations and electron energy balance equation were solved for different pulse repetition rate in a temporally self- consistent manner, with the long term evolution of plasma kinetics followed over multiple excitation/afterglow cycles. Electron rate constants were for the first time taken from the realistic EEDF, which was the result of solving Boltzmann equation in two-term approximation with charged particle collisions taken into account. Laser radiation power was calculated together with external circuits (several magnetic switches are included) self-consistently. Our model includes the plasma-chemical and neutral kinetic processes in Cu/Ne/H₂/HCl mixtures. Two-dimensional thermal radiation transfer was taken into account for the first time. The influence of skin-effect and H₂/HCl additives on CVL characteristics was studied. Detailed hydrogen rotational and vibrational kinetics taken into account in a CVL model allows us to explain experimental results: radial redistribution of laser power, wall temperature increase, prepulse electron temperature and concentration decrease with hydrogen. The model was used for designing new laser system. After that this laser was constructed and gives first results lately. The laser shows good agreement with predictions, in already realized pure Cu mode (without any admixtures) it gives 105 W, whereas the prediction was 117 W.

The design of a large-bore copper vapor laser amplifier (CVA) intended for the application to high-power laser systems operating in the 'master oscillator ('MO-amplifier') mode is described. The discharge volume of the amplifier laser head is 70 mm in diameter and about 2000 mm in length. The results of experimental studies of the CVA operating in the lasing mode at a pulse repetition rate of 4 - 6 kHz and a buffer gas pressure of 30 - 80 Torr are presented in the paper. Stable operation of the CVA was achieved at an output power of 100 +/- 5 W and approximately 1% efficiency.

Impressive improvements in the quality of laser beam and the electric discharge properties of CuBr laser are reported lately as results of our continuing research on the hydrogen effect in copper halide-based lasers. Laser output power, P_out >= 10 W and beam divergence, (theta) <EQ 90 (mu) rad are available from a single-unit medium-scale (2 cm- bore x 50 cm) medium-power (10 - 20 W) CuBr laser fitted with a positive-branch unstable resonator of medium (M equals 73 - 100) magnification. Laser spatial intensity, P_out/(theta) ² increases 5 times compared with the case of no hydrogen added (1390W.mrad^-2 and 280W.mrad^-2, respectively). Electrical field potential measurements in Ne-H₂ mixtures show that in comparison with the pure-Ne-gas case, the near-electrode E- fields are nearly of a factor of 2 lower whereas the far- from-electrode E-field is almost of a factor of 6 higher as the pressure of H₂ additive reaches 0.37 Torr. Energy dissipation in the CuBr laser electrodes has been studied in a typical gaseous environment and with discharge length scaling. The power lost in the electrodes significantly increases not only with a decrease in electrode separation but also more compounds are added to the medium. The total energy dissipated in both electrodes varies between 10% and 30% of the storage capacitor energy.

A simplified model, describing the kinetic processes in a nanosecond pulsed longitudinal Ne-CuBr discharge afterglow, is made. It is shown that the influence of the active zone diameter decrease on the inversion population and hence on the output power and the laser pulse on the 248.6 nm line is due to the more effective population of the upper laser level, because of the higher neon ion density and mainly because of the more effective depopulation of the lower laser level. Optimal discharge conditions for UV laser operation are found for different active zone diameters of the laser tube - 12 mm, 9.5 mm, 9 mm, 8 mm, 5.8 mm, 5.7 mm, 5.2 mm and 4 mm. With diameter reduction a record average laser power of 1.3 W is obtained at multiline output. The highest peak pulse and average output powers are measured on the 248.6-nm laser line for the UV Cu^+I lasers - 3.25 W and 0.85 W, respectively. The obtained specific average laser power is 56.6 mW.cm^-3 at an active volume of 23 cm³.

The automatic decontraction and the retention of stability of the discharge in the wide range of gas-discharge conditions are observed in the repetitively pulsed discharges in metal vapor lasers.

Method of electron concentration (n_e) reducing in an interpulse period is proposed, based on ambipolar diffusion (AD) rate increase to the tube walls. As the AD coefficient D_a equals D(1-T_e/T), the heating of electrons by weak electric field to the T_e <EQ 1 (epsilon) B, yet insufficient for ionization although much higher than the gas temperature T, considerably hastens the process of ion removal to the walls. Effect of the intensified ambipolar diffusion (IAD) was registered experimentally by us in the afterglow of zinc and cadmium metal vapor ion lasers. In this work, computer modeling of the IAD is performed for He- Cu and Ne-Cu discharge afterglows with parameters typical for self-terminated copper vapor laser. As the calculations demonstrate, at helium pressure of about 10 Torr and tube diameter approximately 1 cm, when heating field E of 0.8 - 0.9 V/cm is imposed on afterglow for a time period of 100 microsecond(s) , n_e slides down to values of 10² - 10⁴ times smaller as compared to those without heating. The effect is stronger in helium. The use of IAD in interpulse period would allow, as calculations reveal, up to 20 - 40% increase of pulse repetition rate in the copper vapor laser with small tube diameters and low buffer gas pressures. The excess build up of copper metastables density is prevented by interruption of plasma heating 3 - 5 microsecond(s) prior the onset of a main current pulse.

The processes of temporal evolution of metal vapor longitudinal distribution in the pulse-periodic discharge with the cataphoresis delivery of vapor are investigated. In particular, the solution of a non-stationary diffusion equation for the density of metal vapor, averaged for rather large number of pulses, is derived. The axial distributions of metal vapor at different moments of time are calculated. The criteria of uniformity of these distributions are determined. Time intervals are found for homogeneous distribution establishment in typical pulse-periodic MVLs conditions. These time intervals showed to be fairly small, on the order of second. The obtained results demonstrate good perspectives for the use of cataphoresis in pulse- period MVLs to form the homogeneous active mediums and, as a consequence, obtain high output characteristics of lasers.

An attempt to explain the influence of Cs on pulsed copper vapor laser (CVL) operation is presented. The influence of Cs admixture on the processes of ionization and recombination in a discharge plasma used for excitation of the laser are considered.

Experimental study of sealed-off CuBr laser was performed with the aim to prolong its lifetime. Electrical circuit with a transistor switch was used. Optimal pulse repetition rate corresponding to maximum output radiation power was obtained.

Experimental study of PbBr laser was performed to study its performances and lifetime. Optimal pulse repetition rate was defined. Numerical model of PbBr laser was created to define the optimal Lead vapor pressure to achieve maximum output power and efficiency.

We have studied a self-terminating bismuth-vapor laser at (lambda) equals 472.2 nm with an average output power of 58 mW. Laser action was observed across the entire gas-discharge tube at pulse repetition rates between 3.0 and 5.4 kHz. Laser operation at a moderate buffer-gas pressure (P_Ne approximately 100 Torr) is shown to be feasible. The pulse repetition rates at which laser action occurs are between 500 Hz and 14 kHz.

Traveling-wave lasing is reported on two phenylenevinylene polymers (MEH-PPV, M3EH-PPV), two triphenylamine-vinylene- phenylenevinylene copolymers (TPA-MOP-PPV, TPA-MEH-PPV), and a ternaric condensation copolymer containing TPA-MEH-PV and M3EH-PV sub-units (TPA-MEH-M3EH-PPV). Waveguiding thin films on glass substrates are transversally pumped with picosecond lasers pulses (wavelength 347.15 nm, duration 35 ps). The laser emission occurs between 515 nm (TPA-MOP-PPV) and 646 nm (M3EH-PPV) with a spectral width between 7 nm and 13 nm. The threshold pump pulse energy densities are between 10 (mu) J cm^-2 and 45 (mu) J cm^-2. At high pump pulse energies a saturation of the generated amplified spontaneous emission signal is observed which is thought to be due to exciton-exciton annihilation processes. Additionally a diphenyl substituted phenylenevinylene polymer (DPOP-PPV) is investigated which shows no laser action despite high neat-film fluorescence quantum efficiency ((phi) _F equals 0.72). Photo-induced absorption dominates over stimulated emission and hinders traveling- wave lasing. An absorption and emission spectroscopic characterization of the investigated polymers is carried out. An energy density dependent fluorescence quenching is observed and this behavior is discussed in terms of exciton- exciton annihilation processes.

The main characteristics of interaction of monokinetic electrons with different energies in the range from 0 to 50 eV at an angle 90 degree(s) (electron energy loss spectra, luminescence excitation functions, and luminescence spectra) for some lasing potential organic materials (paraquaterphenyl, 1,4-bis[2-(5- phenyloxazolyl)]benzene (POPOP), 2,5-biphenyloxazole (PPO), perylene, (beta) -binaphthilenoxide (dinaphthofuran), and 4-methylamino-N-(o-tolyl)-1,8-naphthalimide) are presented and analyzed. It was shown the correlation between elastic and inelastic scattering. It was found that the nature of electron and photon excitations is similar. Direct population of triplet states for most of studied compounds is negligible. The substances with intensive longwave singlet band (perylene, POPOP, PPO, naphthalimide) are very attractive for lasing search in electroluminescent cell. Calculation of excitation rates based on Born approximation results in essential error.

In the present work the analysis of the possible ways of energy degradation of electron excited states of 4-methyl-7- hydxyquinolone-2 (Q) and its protolytic species is presented (Figure 1); a ratio of radiative and nonradiative channels of deactivation of energy of electronic excitation is established; constants of photophysical processes (internal and intercrossing conversion), proceeding after act of absorption of light are designed. Study of exited state intramolecular proton transfer (ESIPT) in quinolones is interesting as a source of information on the relative importance of these processes in the photophysics and photochemistry of such molecular systems.

At a twisting of phenyl rings around of single C-C bond in trans-stilbene take place a short-wavelength shift the first (pi) (pi) * transition with decreasing of intensity and mixing (pi) * and (sigma) * MO due to modification of geometry. The planar form of trans-stilbene has a high symmetry and dipole moment in this form is equal to zero both in the ground, and excited states; in nonplanar conformation the molecule obtains some dipole moment. The planar confirmation of cis- stilbene is impossible ((theta) equals 0 degree(s)), as distance between the nearest atoms of hydrogen is equal 0,3 Angstrom. The rotation of rings only around of the double C equals C bond not yield results, which are in good agreement with the experimental absorption spectra. The good agreement of our calculations with the experimental absorption spectra are observed only at rotational angles (theta) equal from 10 to 45 degree(s) together with rotation of phenyl rings around of single C-C bond, (sigma) from 30 to 90 degree(s). The existence of cis-form is possible at (theta) equals 0 degree(s), but at the considerable twisting of phenyl rings rather each other (from 60 up to 90 degree(s)). It is possible to conclude from our calculations that the best emitting properties has molecule of trans-stilbene in planar geometry, at a twisting of phenyl rings around of single C-C bond, the spectral properties of trans-stilbene is similar to cis- conformations. `

A study of the phenol, 4-chlorophenol and 4-bromophenol aqueous solutions, photolysis under UV-irradiation from capacitive discharge KrCl- and XeBr-excilamps at different wavelengths have been undertaken. To specify photolysis efficiency the irradiated solutions have been investigated by spectroscopic methods. To account for obtained results, the quantum-mechanical computation has been invoked.

The second harmonic generation of tunable radiation of the flashlamp-pumped dye-lasers was investigated in different ranges of the spectrum. It was found out that the requirements to beam divergence of the laser radiation grow at increase of width of a spectral line. The pulse-periodic tunable source for UV-range of spectrum (260 - 340 nm) was developed and created. It have output up to some tens mW of an average power, and up to some tens kW of a peak power.

The aim of this work is spectroscopic diagnostics of a discharge in a new compact 'sealed-off' excimer laser. Spatial-time behaviors of the main excited atomic and ionic species, gas temperature and electron density were monitored with ns-gated ICCD camera from spontaneous emission spectra of the discharge. Ignition of cathode hot spots is detected from atomic emission lines of a cathode material. At increased current density cathode hot spots appear after the end of the pumping pulse because of delayed explosion of overheated emission centers on the cathode surface. No constrictions have been developed in the discharge from these spots because the pumping is very short. At highest pulse repetition rate discharge constriction is initiated from accumulated overheating of the boundary gas layer near the cathode surface.

Dynamics of development of single hot spot discharge in SF₆ gas and in the mixture SF₆/C₂H₆ and of its contraction has been studied experimentally. Visualization of discharge development has been performed by a fast shutter CCD camera. Discharge properties have been studied in a wide range of current densities and input energies. It has been found that a single hot spot discharge has a cup- like structure. The diameter of the cathode hot spot is 0.04 cm, while the diameter of the plasma near the anode reach a value of about 3 cm. An increase of the discharge current causes an enlargement of the discharge cross section. The hypothesis of discharge widening is presented and discussed. It has been shown that discharges in the mixture are more homogeneous and stable. Single hot spot allows to realize a discharge current of 2 - 3 kA at input energies of about 1 - 3 J without distortion of discharge homogeneity. When the discharge with three hot spots separated by 5 mm has been investigated, the formation of inhomogeneity from one hot spot occurs at 700 A. Development of a channel with enhanced conductivity from single hot spot in SF₆ gas has been also obtained experimentally in case with advanced preionization.

The simulation of electron multiplication process in near cathode area is done. The analytical approximations for magnitudes, which are describing this process, are offered. The problem of determining the plasma parameters (electronic and ionic densities and currents, electric field strength) at the area, near to the cathode surface, is considered on the base of proposed approximations. The simple formulas, which are defining full current, width of cathode area and a voltage drop as function of field strength on the cathode surface, are presented.

Two effective methods of electron energy distribution function (EEDF) calculation are presented. One of them considers stationary form of EEDF master equation, the second one treats nonstationary form of the last. Two Fortran programs are developed for gas mixtures containing CO₂, CO, N₂, O₂, H₂, He, Ar species. On the whole good or satisfactory agreement with experiment is achieved for most of kinetic properties.

Glow discharge in a gas flow (GDF) in various chambers has been investigated by analytic and numerical methods. In the case of GDF in cylindrical tubes spatial distributions of gas temperature and of electron density were received as series with Bessel functions. For GDF in plane profiled chambers these characteristics were obtained as series with trigonometric and degenerate hypergeometric functions. Transverse glow discharge chambers in electronegative gas flow was investigated numerically by alternating direction method. As a result, two-dimensional distributions of charged particles and of electric potential inside chamber were obtained.

Isotope separation processes operate on very small differences, given either by the Quotient of masses with the same number of electrons or by their mass difference. When separating isotopes of light elements in mass quantities, thermodynamic processes accounting for the quotient, either in diffusion, chemical reactivity or distillation are used. For heavy elements those quotients are very small. Therefore they need a large number of separation steps. Large plants with high energy consumption result from that. As uranium isotope separation is the most important industrial field, alternatives, taking account for the mass difference, as e.g. gas centrifuges, have been developed. They use only a fraction of the energy input, but need a very large number of machines, as the individual throughput is small. Since it was discovered, that molecules of high symmetry like Uranium-Hexafluoride as a deep-cooled gas stream can be ionized by multiple photon excitation, this process was studied in detail and in competition to the selective ionization of metal vapors, as already demonstrated with uranium. The paper reports about the principles of the laser excitation for both processes, the different laboratory scale and prototypical plants built, the difficulties with materials, as far as the metal vapor laser separation is concerned, and the difficulties experienced in the similarity in molecular spectra. An overview of the relative economic merits of the different processes and the auspices in a saturated market for uranium isotope separation, together with other potential markets for molecular laser separation, is contained in the conclusions.

We have developed rapidly tuned RF-pumped CO₂ waveguide laser transmitters for remote sensing in the 9 - 11 micrometers spectral range. The small size, high power and efficiency, and tunability of these lasers offer significant advantages over other laser sources in this spectral region. Employing acousto-optic modulators to achieve random-access tuning at pulse rates up to 100 kHz permits rapid gathering of data on time scales short compared to times for change in atmospheric turbulence and absorption effects, thereby improving the signal-to-noise ratios that can be achieved. Laser system design and performance characteristics of present systems are described, along with proposed concepts to increase optical bandwidths and extend the tuning range to cover the full long-wave atmospheric transmission window from 8 - 12 micrometers .

The research on studying and development of iodine lasers for experiments in the field of ICF, conducted in RFNC- VNIIEF, were resulted in the creation of 120 TWt 12-channel pulse iodine laser facility 'Iskra-5'. Wavelength of radiation is (lambda) equals 1.315 micrometers . 'Iskra-5' installation is designed on the scheme of parallel amplification of pulse, generated by front-end system, in 12 identical amplifying channels. Front-end system includes four main parts: master oscillator (MO), two cascades of preliminary amplification (PA1, PA2) and final amplifier (A0). Radiation from front-end system after A0 passes through the splitting system to the input of amplifying channels. Topics of report are short description of 'Iskra-5' front-end system and analysis of its parameters during previous five years of facility operation. Modernization of master oscillator is reported also. This modernization includes changing of electro-optical mode-locker on acousto-optically mode-locker made from crystalline quartz. Using of crystalline quartz allowed to get 100% depth of modulation on the wavelength of iodine laser radiation under control power about 10 Wt. The analysis of results revealed that using of acousto-optical modulator significantly stabilizes the parameters of front- end system radiation pulse.

Experimental results of initial testing dye-laser 'MLK-02' pumped by a copper vapor laser 'Kulon-10' are presented. Output parameters obtained are the following: average power - 1 and 1.5 W, efficiency - 17.6 and 18.7% at the wavelengths of 670 and 725 nm, respectively. The laser apparatus is supposed to be used for methods of photodynamic therapy.

A copper-vapor laser 'Malakhit' was used to prevent and or treat complications caused by antitumor therapy. Results obtained for 19 adult patients with cancer of the lung, 59 adult patients with cancer of the stomach, and 640 children with malignant and benign tumors are discussed.

The absorption of laser radiation on various atmospheric paths have been estimated basing on the data on spectral composition of HF, DF, and iodine lasers radiation and on the atmospheric molecular absorption coefficient. Applications of these lasers to atmospheric transmission problems require the information on the attenuation characteristics of the atmosphere at each of the lasing frequencies. Calculations have been made of the monochromatic transmission of HF and DF laser radiation for nonhomogeneous atmospheric slant paths. Aerosol extinction, continuum molecular absorption, and line absorption are included in the computations. An approximate Voigt profile has been used to express mixed Doppler-Lorentz line broadening. HF P₂(8) and DF P₂(8) lines are chosen among the presently operational cw chemical lasers for detailed studies.

The paper is devoted to experimental study of discharge and radiation characteristics taking place in Xe one-barrier excilamps at broad variations of excitation pulse parameters and gas fill-pressures. The B-X band of the molecule Xe₂* dominates the lamp spectrum and has high efficiency. Radiation of monatomic lines and luminescence of the lamp bulb can be observed too. The molecule Xe₂* band B-X radiation of luminescence time dependence and luminescence of the lamp bulb quartz are similar, at the same time the radiation of Xe monatomic line (lambda) equals 467 nm has obviously some other form. Depending on excitation conditions, i.e. power, duration and excitation impulse form, a gas discharge Xe excilamp, different by homogeneity level and radiation efficiency types of discharge can be realized. Formation of discharge homogeneity is the necessary condition to obtain high efficiencies of excimer radiation in this type of lamp. In one-barrier xenon excilamps with internal small curvature of an electrode, a homogeneous discharge forms at pressures up to 300 Torr.

In a current report it is offered to provide chemical sample pretreatment by modern sources of spontaneous emission, so- called excilamps. The possible preferences and disadvantages is under discussion. Some experimental results are presented.

The additional processes of excitation of (formula available in paper) excimer molecules in gas-discharge plasma on (formula available in paper) mixtures have been investigated (together with dissociation of mercury dihalides by electronic shock, which is the basic process. The pumping of working mixtures was implemented by high- frequency (f equals 1000 Hz) barrier and surface discharges of nanosecond duration (approximately 100 ns), taking place simultaneously. The essential increase in the amplitude (up to 3 times), radiation pulse duration (up to 2 times) and their back edge (up to 15 times) has been revealed with the addition of molecular nitrogen in the (formula available in paper) working mixture, and also the difference in value of amplitudes of the first, second and third pulses have been revealed. It has been established, that the change in temporary radiation parameters is caused by the transfer of energy from molecular nitrogen in metastable state A³Σ _μ at collisions with molecules of mercury dihalides. One more additional process, increasing the amplitude of the second and third radiation pulses both in the HgBr₂/HgCl₂/He mixtures, and in the HgBr₂/HgCl₂/N₂/He mixtures is the excitation of the HgBr(X²Σ⁺₁₂ and HgCl(X²Σ⁺₁₂) radicals in the B²Σ⁺₁₂-state by the electrons.

The results of an experimental study on the temporal evolution of molecular-ion continua of rare gases using electron- and ion beam pumping are presented. The temporal evolution of radiation bands, which make up the molecular-ion continuum (MIC) has been measured. A hypothesis for a relaxation cascade of excitation energy transfer from doubly charged ions (Rg⁺⁺_n) to singly charged ions (Rg⁺_n) has been analyzed. Results obtained using electron-beam pumping and a comparison with data obtained by other pumping methods allows us to draw the conclusion that for MIC in rare gases, the local maxima's wavelengths do practically not depend on pumping power and pumping method. The ratio of intensities in different maxima during plasma relaxation, however, and the behavior of each maximum with respect to pressure variations do depend on specific excitation power.

The paper is devoted to problems of employment of high- frequency electrodeless lamps as ultra violet (UV) and vacuum ultra violet (VUV) light sources. Some aspects of lamp preparation technology for UV and VUV are considered. The technology, developed in our laboratory, allows to prepare HFEL-s filled with wide spread of chemical elements. Our experience shows that most important filling elements for UV and VUV spectral regions are Zn, Cd, Hg, Se, As, Sn and Pb, Sb, Bi, Tl, Te, I, H, Hg-Cd, Hg-Zn, Se-Te. The requirements for generators are discussed. Some important spectral characteristics of lamp examples are presented.

In this paper, the calculations on decay of voltage, power and excitation energy in barrier discharge excilamps is presented. In order to verify these parameters calculations, measurements on energy input into the gas discharge plasma both using common techniques (calorimeter and volt-coulomb discharge characteristics of discharge) and integration of calculated excitation power were done. The obtained results are in good agreement that points to correct calculations done on necessary excitation parameters in the barrier discharge excilamps.

Experimental study of Xe and Kr radiation spectrum temporal dynamics under pumping by nanosecond e-beam have been carried out for the purpose to determine the dependence of UV radiation efficiency of molecular-ion continua (MIC) on pressure. The results obtained allow to draw a conclusion, that with increase of gas pressure it does happen the change of the main radiating molecules from double-ionized to single ionized ones, and the efficiency of MIC radiation in inert gases decreases. To obtain the laser oscillation at MIC of inert gases is more probable at low pressures, when absorption in active medium is small and MIC radiation efficiency is maximal. It is necessary to use a selective narrow-band resonator in this case. From the point of view of efficient use of e-beam energy the optimal excitation geometry is the longitudinal relatively to optical axis.

In the present paper, Xe-I₂ and He-I₂ glow and capacitive discharge excilamps have been studied. These excilamps emit at iodine monatomic resonance lines in the range of 180 - 210 nm, and on XeI* molecule band ((lambda) _max equals 253 nm). Besides that, by varying pressure and mixture composition, it is possible to control relation between iodine monatomic lines and XeI* molecule band radiation intensity. The efficiency level is up to 10%. The lifetime in sealed-off and quasi-sealed-off modes is up to 1000 h.

Results on investigation of linear and non-linear optical properties, damage threshold and potential efficiencies of biaxial LiInS₂ crystal are represented. Transmission range is 0.4 - 12.5 micrometers at the 0.1 level and 0.5 - 11.0 micrometers at the 0.5 level. Typical absorption coefficients are as low as 0,1 - 0,25 cm^-1 at the maximum transmission range 1.0 - 8.0 micrometers and 1.1 - 2.3 cm^-1 at the CO₂ laser wavelengths. Coefficients of second order non-linear susceptibilities are d₃₁ equals 6.2, d₃₂ equals 5.4 and d₃₃ equals 9.8 pm/V, but damage threshold is as high as 120 - 130 MW/sm² for 36 ns pulses at 9.55 micrometers . The phase-matching is estimated with using of determined Sellmeier coefficients. It is represented in graphic form so as fields of SHG efficiencies. It is shown that LiInS₂ can be used in middle IR OPO pumped by Cu-vapor laser, group-velocity phase matching take place in wide spectral range for sum- and difference-frequency generation of visible, near and middle IR lasers including SHG of 3 micrometers Er laser.

The influence of two-photon absorption on the stimulated Mandelshtam-Brillouin scattering of light in (beta) -picolin- water solution with a singular point has been studied. Values of two-photon absorption coefficient and the imaginary part of a susceptibility of the solution have been calculated. Temperature dependence of the imaginary part of the susceptibility for analyzed solution has been determined.

The results of development and optimization of the working medium of ecological pure radiator working in the range of 130 - 190 nm are presented in this paper. A decaying discharge of a constant current in the quartz or sapphire tube with an interelectrode distance of 50 mm was used for pumping. As working media the mixtures He(Ar, Kr, Xe)/H₂O were used. It was shown that by falling the pressure on discharge interval U_ch equals 800 - 1700 V, in discharge current I_ch equals 5 - 50 mA and partial pressure of water vapor P(H₂O)