This PDF file contains the front matter associated with SPIE Proceedings Volume 6938, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The experimental investigations results of spectral, energy and temporal parameters of the first inductive N₂, FI and CO₂ gas lasers are reported. The excitation system for formation of the achievement the pulsed cylindrical inductive discharge in gas mixtures is described. For the first time the nitrogen inductive laser (337.1 nm) with pulse power of 350 kW was created. The generation energy of 4.6 mJ with the pulse duration (FWHM) of 12±1 ns was achieved. The total efficiency of nitrogen inductive laser was 0.05 %. The laser beam has a ring form with an outer diameter of 43 mm, thickness of 1.5-2.0 mm and the divergence of 0.3 mrad. For FI inductive laser the lasing was observed on 8 lines (623-755 nm). The maximal output energy of 2.6 mJ was achieved in He:F2-100:1 gas mixture. The pulse duration was 80±1 ns (FWHM) that correspond to pulse power of 32 kW. The total efficiency of the FI inductive laser was 0.01 %. The ring laser beam has an outer diameter of 43 mm, thickness of 3.0 mm and the divergence of 0.4 mrad. For CO₂ (10.6 um) inductive laser the maximal output energy of 150 mJ was achieved in gas mixture He:N₂:CO₂ - 8:1:1. The pulse duration (FWHM) was 170 us that corresponds to a pulse power of 0.9 kW. The laser beam has a ring form with dimension of an outer diameter of 33 mm with the thickness about 6.0-6.5 mm and the divergence of 4.0 mrad.

Investigation results of high-frequency XeF, KrF and N₂ lasers with an electrode unit, based on multisectional discharge gap with an inductive-capacitive discharge stabilization, are presented in the paper. The main direction of the research was obtaining the highest pulse repetition rates with their high stability. The pulse repetition rates up to 4...5 kHz were realized in UV lasers at relatively low gas flow velocity (16...19 m/s). The relative root-mean-square (rms) deviation of the laser pulse energy (σ) in the XeF laser was σ = 2.3% at f = 5 kHz, in the KrF laser σ = 3.2% at f = 4.5 kHz, in the nitrogen laser σ = 1.6% at f = 4.5 kHz. Influence of different factors on the stability of the pulses energy of the laser radiation was studied. It is shown that existence of inductive-capacitive decoupling between cathode plates in the KrF (XeF) and N₂ lasers made it possible to increase the limiting frequency for the KrF (XeF)-laser on 1...2 kHz keeping the same σ. The best stability of the laser pulses energy was obtained at location of the preionizer sparks upwards on the gas flow. In the nitrogen laser we recorded periodical change of the σ value.

Activity of our laboratory in the field of pulsed high-current proximity-wall-stabilised discharges - media for XUV/soft X-ray generation and amplification (XUV/soft X-ray lasing), and our effort to demonstrate lasing of discharge-based sources at the wavelength <15 nm are described. While lasing on the wavelength of 46,9 nm (Ne-like Ar ions) is in capillary discharge routinely achieved (due to excitation pumping scheme), lasing on the wavelength below 15 nm either has been demonstrated in laser-created plasma in Ne-/Ni-like ions of metal vapours (also due to excitation pumping scheme) or has been predicted for H-like N ions (recombination pumping scheme). For the excitation pumping of metal vapours a wire exploding in water locally compressed by focused shock wave is being prepared. The recombination pumping of N is examined in the capillary discharge geometry known from the former experiments with Ar, but at higher discharge currents (>60 kA).

In the present paper the perspectives using of excimer media for formation of a short high power laser radiation pulses are discussed. Research results of Gas Laser Laboratory of IHCE SD RAS, Tomsk, Russia in this area are shown.

Optimization studies of optical and power performances of nuclear pumped lasers are performed. It is shown that the laser mix pump rate speed-up from 7 to 30 m/s and laser channel width reduction from 2 to 1 cm allows increasing the average specific energy input by the factor of 1.6 and narrowing the refraction factor measuring interval for 4 times.

The parameters of pulse-periodical TEA CO₂ laser with plate-like electrodes and inductive-capacitive discharge stabilization are investigated. Maximum energy of a laser radiation was 15.9 mJ with maximum of lasing efficiency ~ 1.7% for a gas mixture: CO₂ : N₂ : He = 1 : 1 : 3. The pulse repetition rate above 3 kHz at a gas flow velocity in the discharge gap of ≤ 19 m s^-1 is achieved.

The results of the experimental investigations of the discharge-pumped KrCl (223 nm) excimer laser with the TPI thyratron (pseudo spark gap) as a high-voltage switch are presented. The experimental investigation of the energy and temporal parameters of the pumping and radiation for KrCl laser on the Ne:Kr:HCl mixture with an excitation system of the LC-inverter type based on TPI 10k/20 thyratron was carried out. The comparative analysis of the laser pumping and radiation parameters with those obtained for excitation system based on a spark gap RU-65 as a high-voltage switch was performed. As a result the output radiation energy for a laser with thyratron TPI 10k/20 was obtained to be of 40% higher than that with spark gap RU-65 at the same pumping conditions. The higher output energy and efficiency of the TPI based laser was considered to be due to higher efficiency of energy transfer from storage to discharge circuit and to active media owing to lower energy losses into TPI thyratron in comparison with the RU-65 spark gap. For KrCl excimer laser in Ne:Kr:HCl mixture the total efficiency of 1.5% with output energy of 0.65 J was obtained for the first time.

To increase power density in gas-discharge lasers based on combined DC-CPD discharge technology (DC + Capacitively-coupled Periodic-pulsed Discharge) one have to increase pulse current density of CPD. Thus electrical and chemical processes in CPD were studied in pulse current density limits expanded up to 500 mA/cm². It was shown that CO₂ dissociation rate is increased with current density and pulse repetition rate and is different in near-electrode sheath and in the discharge gap. Catalytic stabilization method of the gas mixture composition is proposed for CPD at higher pulse current densities.

In present paper the results of an experimental research of a qualitative radiation formation with pulse duration of 3.5 and 0.15 nanoseconds in one discharge block of XeCl laser with pump pulse duration of 35 ns at use resonator with SBS mirror are presented.

The review of the investigations of the optical radiation forming of the multi-channel nuclear-pumped lasers performed in VNIIEF is presented. There are several ways to solve the problem of the laser beam number minimization: 1) the using of the generator -amplifier scheme; 2) the phasing of the radiation of several lasers channels by means of the optical coupling devices; 3) the using of consecutive and parallel composition of the laser channels. At present, in VNIIEF the investigations of the generator -amplifier scheme and the laser systems consisted of two, three and four consecutive composed channels have been performed experimentally. Moreover, investigations of parallel composition of two laser channels are in progress now. There are three nuclear-pumped laser systems which were used to investigate the composition methods: LM-4, LM-8 and LUNA-2M, moreover, except the LM-4 these multi-channel systems are being used for carrying out the experiments nowadays.

The spectral-luminescent and lasing properties of the 3-substituted-7-hydroxycuomarins derivatives are studied experimentally and using quantum-chemical calculations using INDO method with spectroscopic parameterithation. The photophysical processes in these compounds were analyzed.

The laser properties and photostability of R6G was investigated in polymer solid-state matrix consisted from copolymers methylmethacrylate (MMA) with 2-hydroxyethylmethacrylate (HEMA) in the 1:1 ratio and in hybrid polymer consisted from the same monomers MMA+HEMA and tetraethoxysilane (TEOS) The 2-nd harmonic of a Nd-YAG laser was used for pumping of active media. It was shown that laser efficiency of R6G in both type of matrix is comparable whereas the laser lifetime of R6G in hybrid material is noticeably longer then in P(MMA+HEMA).

The opportunity of populating of Hg and N₂ levels due to ion-ion recombination is considered. Spectra of a luminescence of mixtures ³He + N₂ + NF₃ (CCl₄) are investigated on nuclear reactor installation. It was supposed, that populating of N₂ (C³Π_u) in processes: N₂ ⁺ + F^- (Cl^-) + M → N₂ (C³Π_u) + F (Cl) + M, will lead to increase of the intensity of the second positive system of nitrogen. However measurements have shown that molecular bands of nitrogen don't amplify at addition of electro-negative gases. Spectra of luminescence of mixtures He + Hg + O₂ (CO₂) are investigated on installation with excitation by α-particles of ²¹⁰Po. It was supposed, that in processes of recombination: Hg⁺ + O^- + M→ Hg* + O + M Hg⁺ + O₂ ^- + M→ Hg ** + O₂ + M will be populated 7³S₁ and probably 6D levels of Hg. The observed increase in intensity of triplet lines of mercury at addition of CO₂ to a mixture ³He + Hg, apparently, is connected with recombination of ions Hg⁺ and O^-.

A number of unique properties of the electric-discharge XeCl laser, like possibility to generate laser pulses with duration from single nanosecond to hundreds ns, continues to attract a research interest to that laser system. It follows from an analysis of the laser characteristics obtained by different groups throughout the world [1], conditions of the laser generation to a great extent influence the output laser characteristics. The highest laser efficiency of 4-5% with the specific radiation energy 2-3 J/l is achieved at the pulse durations of 200-100 ns and pumping power of ~0.5 MW/cm³. Laser regimes characterized by high radiation energy of 7-10 J/l, but lower efficiency of 1-3% has been realized at a pulse duration of ~50 ns and pumping power of 2-10 MW/cm³. An increase of the radiation power becomes possible in regimes with a short pumping pulse of 30-20 ns, but at the cost of the laser efficiency, which decreases to 2-3%. The aim of the present work was a search of some general (independent on the pumping regimes) relationships, which could be used as a guideline for the choice of the initial conditions for creation of lasers with desirable parameters. Computer modeling was used as a research method, since it allows to a full extent explore the relation between the output characteristics of a laser and the initial conditions.

An interest to properties of the discharge in gas mixtures with SF₆ is justified by a wide use of such mixtures in the electron and commutation apparatuses and in the pulse discharge HF/DF lasers. Such lasers are considered to be perspective sources of radiation in the 2.4-3.2 μm range of the wave lengths. Experimental studies of the discharge in mixtures Ne/SF₆/C₆H₁₄ [1] and SF₆ - C₂H₆ [1, 2] have shown, that under certain conditions the discharge area extends, and spreads over the whole surface of electrodes. Discharge in the pure SF₆ (P = 78 mBar) [3] was shown to expand in width from ~ 2.5 mm to ~ 3.5 mm. The mechanism of such an expansion till now remains unclear. The present paper is devoted to computer modeling of kinetic processes in non-uniform plasma in the SF₆ gas. The kinetic processes affecting temporal and spatial distribution of the current density in non-uniform plasma are revealed.

The gas diode current-voltage characteristics at the voltage pulses applied from the RADAN and SM-3NS pulsers, and generation of an supershort avalanche electron beam (SAEB) have been studied experimentally in an inhomogeneous electric field upon a nanosecond breakdown in an air gap at atmospheric pressure. Displacement currents with amplitude over 1 kA have been observed and monitored. It is shown that the displacement current amplitude gets increased due to movement of the dense plasma front and charging of a "capacitor" formed between plasma and anode. The SAEB generation time relatively to the discharge current pulses and the gap voltage were determined in the experiments. It is shown that the SAEB current maximum at the pulser voltages of hundreds kV is registered on the discharge current pulse front, before the discharge current peak of the gas diode capacitance, and the delay time of these peaks is determined by the value of an interelectrode spacing. The delay time in case of a gap of 16 mm and air breakdown at atmospheric pressure was ~100 ps, and in case of 10 mm it was less than 50 ps.

Variations in the energy performance of a self-terminating Sr-vapor laser (SrVL) are examined. The active laser volume is varied between 20 and 650 cm³. A linear relation is revealed between the average power delivered by the SrVL and its active volume. The SrVL efficiency is found to increase with active volume and to be comparable with that of a copper-vapor laser for an active volume V = 650 cm³ (0.45 %). As the volume is increased, the total lasing pulse duration increases from 30 to 120 ns. The beam divergence problems associated with the use of a Fabry-Perot cavity or an unstable resonator of the telescopic type are discussed. A total average power of 13.5 W is obtained from V = 650 cm³ at a lasing PRR F = 19 kHz. The output power generated at different laser wavelengths is as follows: 10.4 W at λ = 6.456 μm, 2.6 W at λ = 3 μm, and 0.5 W at λ = 1 μm. The wavelength dependence of the lasing pulse duration is considered.

The lasing characteristics of red-emitting dyes in ethanol excited by Nd:YAG laser second-harmonic radiation are examined. The Nd:YAG laser was pumped by a diode matrix. The pump pulse repetition rates (PRRs) were 2.5 - 10 kHz and the pulse duration was 60 - 300 ns. The following dyes were evaluated: oxazine 17, DCM, DCM_sp, and pyridine 1. The conversion efficiency for oxazine was 25 % without wavelength selection and 15 % with wavelength selection over the tuning range from 630 to 700 nm. The Nd:YAG and dye laser designs used are described elsewhere [1,2].

A high power accelerator for photolytically pumped XeF (C-A) short pulse amplifier is described. The 450 keV, 250 ns (FWHM) radial e-beam is injected into cylindrical 30 cm diameter gas chamber through the 15×120 cm four foil windows. Total energy of e-beam penetrated foils is 3.7 kJ. E-beam pumped energy absorbed in argon (3 bar) is about 3 kJ.

The results of investigations of mechanical, optical and laser characteristics of ceramics made from neodymiumactivated yttrium oxide are presented. The ceramics was fabricated with the use of a new technology including Laser synthesis of nanopowders and their magnetic pulsed compaction (LSN&MPC). The fracture toughness Κ_IC = 0,9 - 1,4 MPa•m^1/2) and microhardness (H_V = 11,8 GPa) of the ceramics have been determined. It has been found that ceramic samples sintered in the temperature range from 1550 to 2050°C have (1 - 150) vol. ppm porosity and optical loss coefficient α_{1,07 μm} = 0,03 - 2,1 cm^-1. It has been shown that pore content in this range did not influence on the optical loss coefficient. Laser generation at λ_g ≈ 1,08 μm with a slope efficiency of 15 % at laser diode pumping has been obtained in 1.1 mm thickness sample with α_{1,07 μm} = 0,03 cm^-1.

Using two optical acoustic approaches we experimentally investigated spatial location of filament zone of propagation channel of focused laser radiation. For femtosecond pulses passing in air it was shown that nonlinear focus length had spatial scale of 1/P at initial power P moderate for self-focusing and at optical system focus distance significantly lower than Rayleigh beam length. The results of experimental optical acoustic investigation of femto- and nanosecond pulses attenuation by some biological tissues (muscular tissue, adipose tissue, cutaneous covering, and milk) and optical breakdown thresholds on these one are presented. It was shown that penetration depth of short laser pulse radiation into biological tissues is the same as for longer one. However, amplitude of acoustic response to a process of interaction of femtosecond laser pulse with biological tissue is larger in several times than that to interaction with nanosecond pulses of the same power and spectral distribution. The obtained threshold values can be interesting for tabulation of limit allowable levels of irradiation at work with laser radiation. Such values are unknown for femtosecond laser pulses today.

Gain characteristics of a photolytically driven XeF(C-A) laser amplifier are studied experimentally in the unsaturated amplification regime. The gaseous active medium is optically pumped by the vacuum-ultraviolet (VUV) radiation from two large-area multichannel surface discharges initiated along opposite walls of the amplifier chamber. Total gain factor of 10² is obtained for the ultrashort optical pulses under multipass amplification in the active volume of 40×18×4 cm³ dimensions with a spatially homogeneous gain distribution. Spectral measurements reveal a good conservation of the seed pulse spectrum. Small-signal gain reaching 2×10^-3 cm^-1 is observed for the blue-green seed pulses of 150 fs duration, as well as for the continuous seed radiation at 488 nm. The obtained gain values, being compared with the gain calculated for the measured pumping radiation power, indicate that the quantum yield of the XeF(B) formation as a result of the XeF₂ photodissociation is high and approaches unity within the spectral band of the XeF₂ VUV photodissociation continuum.

Experimental results of initial testing dye-laser "LITT-PDT" pumped by a copper vapor laser are presented. "LITT PDT" is a modern laser medical complex on CVL-pumped dye laser, generating radiation in a red spectrum area with a tuning wavelength of 630 - 700 nm and preserving high intensity of radiation on each wavelength, necessary for treatment by a photodynamic therapeutic method (PDM). Radiation in a red spectrum area (630 - 700 nm) enables treatment for oncological diseases by PDM using any photosensitizer. The given laser medical complex, generating radiation simultaneously on yellow and green discrete spectrum lines, makes methods of low intensive laser therapy for treatment of precancer and dermatological diseases possible.

Spatial-time behavior of transversally excited pulsed volume discharge in argon is investigated by spontaneous emission spectroscopy and different imaging techniques. VUV Ar₂* emission, UV-VIS continuum and Ar* red lines are used for direct monitoring of discharge homogeneity in the breakdown and recombination stages. Experimental data indicate that Ar* atoms and Ar₂* excimers are created exclusively in the positive column of the discharge, not in near-cathode zones. These zones (cathode sheath and negative glow), however, are the main sources of UV-VIS continuum. The discharge is homogeneous during the first powerful breakdown pulse and fills the whole space between electrodes. Secondary excitation pulses initiate oscillations of plasma emission and longitudinal fragmentation of the discharge into separate zones. Fragmentation is connected with dynamical change of the electron emittance of heated and cold electrodes. Additional electrons, produced during secondary excitation pulses, convert effectively the reservoir of long-lived triplet Ar₂* molecules to fast-emitted singlet Ar₂* excimers - sharp spikes of VUV (126 nm) emission are observed. Double-pulse discharge pumping regime is suggested for easier achievement of the lasing threshold for rare gas excimer lasers.

Pre-production models of excilamps developed in the laboratory of optical radiation are described; main characteristics of radiators and their power supplies, portable UV-excilamps of the barrier or capacitive discharges, and also powerful VUV-excilamps of the barrier discharge which can be used for cleaning or modifying material surfaces are presented.

Excimer and exciplex UV/VUV sources excited by Dielectric Barrier Discharges represent a promising technology for industrial applications where powerful and efficient UV sources are needed. According to previous work, the most suited power supply waveform for coaxial DBD Excilamps is a unipolar pulsed voltage excitation of some kilovolts at some hundred of kilohertz with a duty cycle around one percent. We present here new concepts for energy supplying of coaxial DBDs, based on the direct control of the current in the lamps. These concepts have been tested by means of simulation models developed in our department and the time evolution of the UV radiation is presented for various considered current waveforms. Based on these results, a power supply topology has been designed for an efficient power transfer to the Excilamp. It is based on a converter which controls the current flowing through the DBD. The results concerning the coupling of this converter with a DBD load are commented.

The various dielectric barrier discharges (DBD) lamps and plasma panel prototype designs developed in VNIIEF are presented. The lamps given, depending on a configuration of electrodes, it is possible to divide into three types: 1) a lamp with a plane-parallel configuration of the electrodes, intended for researching of barrier discharges parameters and UV-radiation of various mixes. The design of this lamp allows changing electrodes and varying distance between them; 2) lamps of cylindrical geometry. The external electrode is a spiral or a grid, and internal electrode is a metallic foil. Such design of lamps is the most widespread; 3) lamps with a planar configuration of electrodes. There are two types of lamps with a planar configuration of electrodes: 1) plasma panel prototypes and 2) lamps with ceramic barriers. Plasma panel prototypes are increased (in 50-100 times) copies of plasma display panels (PDP) and are intended for researching of the processes taking place in PDP. Using ceramic barriers of high capacity in DBD lamps allows receiving bigger power density of UV-radiation, than in case of glass (quartz) barriers.

The study of features of XeBr-excilamp (282 nm) and low-pressure Hg-lamp (253.7 nm) radiation impact on Escherichia coli bacterial culture are presented. It is shown for the first time that both sources of radiation have comparable germicidal action. The prospects of a new bactericidal radiation source - XeBr-excilamp - are discussed.

The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained. Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.

The results of investigations of dielectric barrier discharges parameters and UV-emission of Xe/SF₆ (50:1) mixture related to the pressure and the distance between electrodes are presented. The basic source of UV-emission in Xe/SF₆ mixture is XeF^* excimer, whose emission band center is positioned at 354 nm. The mixture pressure was varied in the range from 40 to 180 Torr, and the distance between electrodes changed in range from 3 to 11 mm. The distance between the electrodes and the gas pressure were selected out so that pd-product should be constant. The experiments conducted display that for pd = const in the pressure range of 70-180 Torr there are some regularities which are partly similar to the scaling laws of gas discharge, namely: the current density ~ const; the power dissipated by the discharge ~ 1/p^0.3; UV emission power ~ 1/p; the efficiency of lamp ~ 1/p^0.8; the current pulse duration ~ 1/p^0.3. The highest efficiency (6-8%) was reached for 30-50 Torr gas pressure.