The layout and performance of the single beam Asterix IV high-power iodine laser operating either at the fundamental wavelength at 1315 nm or the second or third harmonic at 658 nm and 438 nm, respectively, is described. Every 20 minutes Asterix IV can provide output pulses with durations ranging from 0.4 ns to several ns with pulse energies of up to 2.1 kJ and pulse powers reaching 3 TW. Preliminary experiments and calculations reveal that by pumping Ti:S disks with the 3(omega) -radiation of Asterix IV much higher powers in the multi-100 TW region can be attained. Since 1988 the laser fired 6500 target shots as a reliable tool. As a selection among numerous experiments three highlights are dealt with: (1) uniform megabar shock waves in solids, (2) XUV opacities in hot dense Al, Fe, and Ho, and (3) lasing on the J equals 0 - 1 line of neon-like ions using the prepulse technique.

Since the mid 1960s laser fusion problems are the subject of active study in many countries of the world. To achieve self-sustaining fusion reaction, the DT fuel densities of 100 - 200 g/cm³, specific areal densities of 0.3 - 0.5 g/cm², and ion temperatures of 3 - 5 keV are required. It is a rather difficult task to realize these extremely high parameters using high-power laser radiation. For the past thirty years performance of various types of targets has been studied including direct-drive and indirect drive targets with single- and multilayered shell pellets. Numerous factors which take effect in implosion physics were investigated. A rich calculational and theoretical material has been obtained. There have been developed and built high-power laser facilities at several laboratories worldwide, some of them are operational. Their parameters are given. All the facilities employ the same optical scheme namely the scheme of direct amplification, and this is one of the reasons for a relatively low efficiency. The main physical results obtained in laser ICF are given. (truncated)

The performance of a repetitively pulsed, 70 joule, closed cycle 1.3 (mu) M photolytic atomic iodine laser with excellent beam quality (BQ equals 1.15) is presented. This BQ was exhibited in the fundamental mode from a M equals 3.1 confocal unstable resonator at a 0.5 Hz repetition rate. A closed cycle scrubber/laser fuel system consisting of a condensative- evaporative section, two Cu wool I₂ reactor regions, and an internal turbo-blower enabled the laser to operate very reliably with low maintenance. The fuel system provided C₃F₇I gas at 10 - 60 torr absent of the photolytic quenching by-product I₂. Using a turbo- molecular blower longitudinal flow velocities greater than 10 m/s were achieved through the 150 cm long by 7.5 multiplied by 7.5 cm² cross sectional photolytic iodine gain region. In addition to the high laser output and excellent BQ, the resulting 8 - 12 microsecond laser pulse had a coherence length greater than 45 meters and polarization extinction ratio better than 100:1. Projections from this pulsed photolytic atomic iodine laser technology to larger energies, higher repetition rates, and variable pulse widths are discussed.

The operations at VNIIEF large-sized laser facilities and the VNIIEF advanced projects of laser facilities for ICF and fundamental physics investigations are discussed. Iodine laser and phase conjugation physics are treated. The possibility of the monopulse laser channel development is shown with energy up to 70 kJ in the single beam. A brief review is presented of a 10 MJ laser project and the high explosive iodine laser (HE-laser) with phase conjugation is considered as the possible means of solving the ICF problem in the fast ignition concept. We suggest the way of quasi stationary superhigh light field production by the focusing power of laser beams into supersmall volume (wavelength orders size).

With the use of kinetic models for a photodissociation iodine laser the calculation of the effective rate constants for chemical reactions in a gaseous active mixture is carried out in the case of a strong influence of molecular collisions. The analysis uses a detailed reaction scheme and Lindemann's collisional mechanism. A list of measured values of rate constants for all reactions occurring in the photodissociation iodine laser active volume for the most important perfluorocarbon radicals is attached.

The plasma produced when a powerful laser pulse is focused onto a target surface in vacuum can provide a copious source of highly charged ions. Ions can then be extracted from the plasma to form a high current, short pulse length ion beam. Experimental laser ion sources have been the subject of investigation in medical physics and particle accelerator applications; a laser ion source is an option for the injection system of heavy ions for the Large Hadron Collider at CERN where a high intensity lead ion beam is required. This paper describes work carried out at CERN to develop a carbon dioxide laser ion source.

Principal parameters of KH_2(1-x)D_2xPO₄: the optical absorption and the refractive indices dispersion in a wide range, important for frequency conversion of iodine laser radiation are investigated. The use of 'skew' FC elements is proposed. Tuning curves have been calculated for 'normal' and 'skew' FC elements. The doubling and tripling 'skew' FC elements are used in large iodine laser installations: 'Iskra-IV' (Russia) and 'Perun' (Czech).

The two types of high rate growth technology of KDP-type crystal are observed. This technology will be used for effective producing of crystal elements for high-energy laser systems. The recent achievements (in particular the obtaining of 380 by 230 by 50 mm Z-plate from KDP crystal) are reported.

In this paper we present and discuss the results of our experiments concerning the study of stimulated Brillouin scattering (SBS) at the laser Perun which have been performed since the last workshop (Bechyne 1992).

Smoothing of ablation pressure profile by controlling the position of the critical surface was explored using a double pulse regime for plasma formation. In the experiment performed on the PERUN single beam iodine laser facility ((lambda) equals 1.315 micrometer, E equals 40 - 50 J, conversion to blue approximately 50%) variations of the distance between the critical and ablation surfaces are achieved by changing the time delay and intensity ratio of the heating blue (third harmonic) irradiation of the Al-target through a preformed red (second harmonic) plasma.

The requirements for the laser facility based on illumination uniformity calculations which allow the user to achieve implosion of 10³ are formulated. The experimental results of the improved direct drive target illumination uniformity are presented. Using it for smoothing properties of the plasma phase plate (PPP) is proposed. PPP parameters for spatial and temporal smoothing of DDT illumination nonuniformities are evaluated.

We report about first experiments on turbulent mixing of Al and Au thin layers at laser acceleration of three-layer Si-Al-Au targets irradiated with iodine laser Iskra-4. A composition of diagnostic complex and first results are presented.

A space-resolved spectrum was obtained using a flat-field XUV spectrograph system, composed of a varied line-spacing concave grating, a toroidal mirror, and a 40 micrometer- width slit. The toroidal mirror is used in order to compensate for the astigmatism due to the grazing incidence of light at the grating. The spectral resolution of the spectrograph system was measured with the XUV spectra emitted from laser plasma produced by an iodine laser. The spatial resolution of the spectrograph system was obtained by calculating transverse ray aberrations with the wave front aberration for the system.

Thermoluminescent dosimeters LiF:Mg,Ti (TLD100), LiF:Mg,Cu,P (GR200A) and CaF₂:Dy (TLD200) as well as Si commercial photodiodes, Polish production, BPYP44 type, were used for time-integrated absolute measurements of x-ray emission from laser-produced plasmas generated by a Nd:glass laser or an iodine photodissociation laser. All the detectors were calibrated by application of radioactive standard sources. Calibrated responses to x-ray radiation emitted from a laser-produced Al plasma are compared and a discrepancy in the results is discussed.

Interferometry measurements of zinc, copper and iron line plasmas created by the iodin laser PERUN ((lambda) equals 1.315 micrometer, (tau) approximately equals 400 ps FWHM) with intensities equivalent to those generated by low-level prepulses in the collisional excitation soft x-ray lasers (5 times 10⁹ minus 1.3 times 10¹¹ Wcm^-2) are presented. The interferograms were taken with 4 and 10 ns delays with respect to the peak of the drive laser pulse using the third harmonic of the iodine laser ((lambda) equals 438 nm). Preliminary results of electron density profile reconstructions in the plane perpendicular to the line plasma axis are reported.

In this contribution we outline our program aimed at obtaining an efficient soft x-ray laser at the wavelength 25.5 nm, using collisional excitation in a neonlike iron plasma. The goal of the research that we are pursuing is to develop a relatively small-scale soft x-ray laser that would be accessible for a variety of applications. A driver available for us is the laser iodine photodissociation laser system PERUN, providing on the order of 40 joules in on the order of 400 ps (FWHM) pulses at the fundamental wavelength 1.315 micrometer. Theoretical analysis based on Z-scaling as well as detailed computer modeling of neonlike Fe plasmas suggest driving energies of approximately equals 15 Jcm^-1 should be sufficient to generate high gain coefficients (up to 7 cm^-1) on the J equals 0 minus 1 line at 25.5 nm. The modeling reveals that a 1.315 micrometer iodine driver is more efficient in producing J equals 0 minus 1 amplification in this moderate-Z system than a 1.06 micrometer Nd:glass driver. As optimizing of pumping conditions is imperative for the feasibility of the project, we have started our experimental effort by investigating plasmas analogous to those created by a small-level prepulse, i.e. by intensities ranging from approximately 5 multiplied by 10⁹ to approximately 1.3 multiplied by 10¹¹ Wcm^-2. Preliminary results of this study are discussed elsewhere in this Proceedings.

Results of an experiment aimed at a detailed characterization of line plasmas created by intensities equivalent to those generated by low-level prepulses in the collisional excitation soft x-ray lasers are presented. Electron density profile in the plane perpendicular to the line plasma axis, at times 4 and 10 ns subsequent to the laser pulse, time-integrated electron temperature and time-integrated lateral extent of the plasma were obtained. These parameters were studied for zinc, copper and iron plasmas created on slab target by approximately 400 ps (FWHM) pulses of an iodine laser ((lambda) equals 1.315 micrometer) giving rise to irradiances ranging from approximately 4.8 multiplied by 10⁹ to approximately 1.2 multiplied by 10¹¹ Wcm^-2.

Laser beam focus position was varied with respect to the target surface to obtain the maximum current of highly charged Ta ions from laser-produced plasma in the far expansion zone. The experiments prove that the optimum position must be settled with the accuracy plus or minus 125 micrometers.

The impact acceleration of electrons by resonance absorption on x-ray emission is studied via simple model for extremely short scale lengths density profiles relevant to interaction of intense subpicosecond laser pulses with solid targets. The increased depth of x-ray emitting layer in target is shown to be able to account for the experimentally observed increase in integrated x-ray emission, when the interaction of p-polarized laser radiation is compared with the interaction of s-polarized laser radiation for the same absorbed energy for both polarizations.

The major effort in German research work related to oxygen-iodine laser technology is devoted to investigations of a supersonic multikilowatt laser device. The laser facility and latest performance data are presented and compared with the international state-of-the-art. The laser operation is supported by a number of small scale basic experiments aimed at the diagnostics of O₂(¹(Delta) ), the visualization of iodine mixing, the chemical properties of the basic constituents and the simulation of liquid jet type generators. Special emphasis is given to the perspectives of COIL industrialization. Propagation of iodine laser radiation and a concept for excited oxygen generation based on fullerenes also are addressed.

Chemical oxygen iodine laser (COIL) is the only laser expected to be applied for thick plate cutting, for instance, by high laser power over 5 kW transferred to the processing fields by the optical silica fiber. As a result of the first stage of industrial COIL development, a 1 kW subsonic COIL was delivered as a commercial processing device first in the world in 1992. The supersonic COIL development was carried out at the second stage and the output power of over 5 kW was obtained in 1995. Using this high power beam, superiority of the COIL as an industrial laser was studied by processing metals.

Development of the high pressure singlet oxygen generator (SOG) is a very important aspect for chemical oxygen-iodine laser (COIL). Increasing of oxygen pressure up to 30 torr and more at conserving high O₂(¹(Delta) ) yield and maintaining BHP temperature at minus (10 divided by 20) degrees Celsius permits us to decrease ration [H₂O]/[O₂] to 5% and less. In this case COIL can operate successfully without a water vapor trap. With raising the total pressure Reynolds number increases too, diminishing boundary layers in supersonic nozzles and improving pressure recovery. The weight and dimensions of the SOG and laser become reduced for the same gas flow rate. For solving these problems the jet SOG has been suggested and developed in Lebedev Physical Institute, Samara Branch. The advantages of the jet SOG consist of the following: (1) Large and controlled specific surface of contact liquid-gas provides for high mass transfer efficiency. (2) High jets velocity guarantees fast basic hydrogen peroxide (BHP) surface renovation. (3) High gas velocity in the reaction zone diminishes O₂(¹(Delta) ) quenching. (4) Efficient gas-liquid heat exchange eliminates the gas heating and generation water vapor due O₂(¹(Delta) ) quenching. (5) Counterflowing design of the jet SOG produces the best conditions for self-cleaning gas flow of droplets in the reaction zone and gives the possibility of COIL operation without droplets separator. High pressure jet SOG has some features connected with intrachannel jet formation, free space jets reconstruction, interaction jets ensemble with counter moving gas flow and drag part of gas by jets, disintegrating jets, generation and separation of droplets, heat effects, surface renovation, impoverishment BHP surface by HO₂^- ions, moving solution film on the reaction zone walls, etc. In this communication our current understanding of the major processes in the jet SOG is set forth. The complex gas and hydrodynamic processes with heat and mass transfer, chemical reactions, generation of the relaxing components with high energy store take place in the SOG reaction zone. It is impossible to create a sufficiently exact model of such a jet SOG taking into account all the enumerated processes. But some approximations and simplifications allow us to determine what the main jet SOG parameters parts are for designing COIL.

The chemical oxygen iodine laser (COIL) is an attractive candidate for efficient power scaling at short wavelengths. High specific power output from supersonic operation leads to compact devices. The German Aerospace Research Establishment (DLR) started experimental investigations of a multikilowatt supersonic COIL at its Lampoldshausen rocket test site in 1994. The excited oxygen is produced by a rotating disk generator. Currently the laser is operated without a cold trap. After the injection of the iodine, the laser gas is expanded to an isentropical Mach number of 1.8 by a multi-element grid nozzle. At present, laser power at about 5 kW and radiation times up to one minute are realized. The paper discusses the general setup of the device and reports on some selected laser output characteristics.

The performance of cw supersonic chemical oxygen-iodine laser (COIL) is reported. The maximum chemical efficiency of 7.4% with the chlorine flow rate of 500 mmol/s is obtained and output power is up to 3.7 KW.

Pulsed chemical oxygen-iodine laser with a discharge generation of atomic iodin is described. Having the output energy like that with photolysis iodine atoms generation such a laser exhibits higher plug-in efficiency. The efficiency value of 91% is reported. Pulse power of 100 kW was obtained which exceeds two orders of magnitude that for cw laser with the same chlorine flowrate. Repetitively pulsed operation is reported.

The losses in various COIL elements with pressure growth are analyzed. The singlet oxygen generator (SOG) and the iodine mixing area, expected to cause the man losses in the working gas mixture, are discussed. High pressure SOG requirements are formulated and a new SOG scheme trying to use the advantages of aerosol and jet types of reactor is presented. Results of first experiments on the new reactor model are given. According to the first results, Cl₂ utilization is high and singlet oxygen concentration in the reactor output is acceptable enough. Requirements for a mixing system to minimize the relaxation losses are specified. Applicability of the GDL mixing systems to COIL is analyzed.

To work out specific laser system, to optimize their operating conditions it is necessary to have a complete description of the kinetic processes in active media and exact values of the reactions rate constants. The detailed study of process kinetics in COIL were discussed in a number of papers and a review on the rate constants at oxygen-iodine media has been prepared and published in Russian language. The present article is a short variant of this review.

Jet singlet oxygen generator (JSOG) is one of the most efficient sources of electronically excited O₂(¹(Delta) ). The JSOG can operate at very high partial O₂(¹(Delta) ) pressure. This feature of JSOG allows supersonic COIL operation without water vapor trap. The prediction of output parameters of JSOG is very important for correct design and engineering of COIL. The one-dimensional model of JSOG has been developed to predict output parameters (chlorine utilization, O₂(¹(Delta) ) yield). The comparisons of calculated and measured output parameters are presented. The main attention is paid to discrepancies of calculated and measured output parameters and limitation of the one-dimensional model. It is shown that for extremely high pressure JSOG the role of effects that cannot be included into a one-dimensional model is very important. The difference between input and output BHP temperature in JSOG is correlated with chlorine utilization and O₂(¹(Delta) ) yield.

The instability of the liquid jets in a jet singlet oxygen generator for oxygen-iodine lasers may limit the operational conditions and the scalability of such generators. Therefore the type of instability and the breakup behavior of jets is investigated experimentally for varying operational conditions. Jets of basic hydrogen peroxide are simulated by the use of glycerin solutions with different viscosities. Two experimental setups with optical observation of the jet development are described. Transition from laminar to turbulent jets, the associated breakup modes and the beginning of jet dissolution by surface spraying are observed. For generator relevant jet diameters intact jet lengths were found to be limited to approx. 25 cm. Jets with driving pressure of more than 3 bar exhibited strong spraying from their surface. The jet diameter shrinks with increasing driving pressure.

An effect of various arrangement of liquid jets and jet diameters on singlet oxygen yield, residual chlorine and water vapor content has been studied experimentally in a jet singlet oxygen generator for a chemical oxygen-iodine laser.

A new concept of singlet oxygen generator with respect to a chemical oxygen-iodine laser has been investigated experimentally. The idea is based on the photodynamic effect (a photo- assisted transfer of energy) in the system of solid photosensitizer -- dioxygen -- source of UV/VIS radiation for singlet oxygen production in gaseous phase. Preliminary experiments on fullerenes C₆₀/C₇₀, methylene dye and phtalocyanine like substance, respectively, used as solid photosensitizers have been attempted.

A brief review of the investigation results of chemical lasers based on the chain and nonchain reaction of fluorine with hydrogen (deuterium) made in the Russian Federal Nuclear Center (VNIIEF) is presented in this report.