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Thermochemistry, kinetics and spectroscopy of KrF and Kr{sub 2}F

Description: The subcontract from Los Alamos National Laboratory to Kansas State University has been completed and this is the final report. The progress under this contract is described in three sections (i) electronic quenching kinetics of KrF(B,C) and Kr{sub 2}F(4{sup 2}{Gamma}) molecules, (ii) photochemical excitation of van der Waals molecules containing Xe and Kr, and (iii) cumulative listing of papers published with support of this contract.
Date: January 1, 1995
Creator: Setser, D. W.
Partner: UNT Libraries Government Documents Department

April 25, 2003, FY2003 Progress Summary and FY2002 Program Plan, Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers,and Complementary Technologies, for Applications in Energy and Defense

Description: The High Average Power Laser Program (HAPL) is a multi-institutional, synergistic effort to develop inertial fusion energy (IFE). This program is building a physics and technology base to complement the laser-fusion science being pursued by DOE Defense programs in support of Stockpile Stewardship. The primary institutions responsible for overseeing and coordinating the research activities are the Naval Research Laboratory (NRL) and Lawrence Livermore National Laboratory (LLNL). The current LLNL proposal is a companion document to the one submitted by NRL, for which the driver development element is focused on the krypton fluoride excimer laser option. The NRL and LLNL proposals also jointly pursue complementary activities with the associated rep-rated laser technologies relating to target fabrication, target injection, final optics, fusion chamber, target physics, materials and power plant economics. This proposal requests continued funding in FY03 to support LLNL in its program to build a 1 kW, 100 J, diode-pumped, crystalline laser, as well as research into high gain fusion target design, fusion chamber issues, and survivability of the final optic element. These technologies are crucial to the feasibility of inertial fusion energy power plants and also have relevance in rep-rated stewardship experiments. The HAPL Program pursues technologies needed for laser-driven IFE. System level considerations indicate that a rep-rated laser technology will be needed, operating at 5-10 Hz. Since a total energy of {approx}2 MJ will ultimately be required to achieve suitable target gain with direct drive targets, the architecture must be scaleable. The Mercury Laser is intended to offer such an architecture. Mercury is a solid state laser that incorporates diodes, crystals and gas cooling technologies.
Date: October 25, 2005
Creator: Meier, W & Bibeau, C
Partner: UNT Libraries Government Documents Department

High-average-power excimer laser. Final report on Task 2 of Phase II of 1 July 1977-31 October 1977. [KrF]

Description: The design and operating characteristics of a KrF laser which has achieved a record average output power of 40 watts and an efficiency of 0.4% at a pulse repetition rate of 1 KHz by utilizing rapid, closed cycle gas flow and thyratron switching are described. The gas transport laser (GTL) used was a GTE Sylvania model 971 laser (a 1500 W CW CO/sub 2/ laser) modified for pulsed operation with fluorine gas mixes. The optical cavity, electrode configuration, and pulse forming circuitry used with the GTL were first optimized in principle using a static (no gas flow) system. Several different mirror configurations, pulse forming circuits (including basic designs and circuit components), and electrode configurations (including shapes and methods of pre-ionization) and gas mixes were tried before selecting the optimum combination to be used in the GTL. Operating at a pulse rate of 2 pps, an applied voltage of 24 KV, and filled with 50 torr Kr, 4 torr F/sub 2/, and 700 torr He, the static laser produced 50 mJ of output pulse energy at an efficiency of 0.82%. At a pressure of 1500 torr, the laser produced 78 mJ at an efficiency of 1.6% and 100 mJ at an efficiency of 1.1%. (WHK)
Date: January 1, 1977
Creator: Fahlen, T.S.
Partner: UNT Libraries Government Documents Department

Superfine laser position control using statistically enhanced resolution in real time

Description: An electronic control system is described which analyzes digitized TV images to simultaneously position 96 time-and-space multiplexed beams for a large KrF laser system. Degradation of position resolution due to the intervals between digitization is discussed, and improvement of this resolution by using inherent system noise is demonstrated. The methods shown resolve arbritary intensity boundaries to a small fraction of the discrete sample spacing.
Date: January 1, 1985
Creator: Kortegaard, B.L.
Partner: UNT Libraries Government Documents Department

Temperature lowering in cryogenic chemical-synthesis techniques and system

Description: When evaluating a chemical synthesis process for a reaction that occurs on the cryogenically cooled walls, it is sometimes necessary to reduce the wall temperatures to enhance the chemical process. To evaluate the chemical process at lower than atmospheric boiling of liquid nitrogen, we built a system and used it to reduce the temperature of the liquid nitrogen. The technique of lowering the liquid nitrogen temperature by reducing the pressure of the boil-off is established knowledge. This paper presents the engineering aspects of the system, design features, equipment requirements, methods of control, and results of the chemical synthesis. The heat input to the system was {approx}400 watts, placing a relatively large demand on the pumping system. Our system is a scale-up of the small laboratory experiment, and it provides the information needed to design an effective system. The major problem encountered was the large quantity of liquid escaping the system during the processing, placing a large gas load on the vacuum system.
Date: August 1, 1993
Creator: Martinez, H. E.; Nelson, T. O. & Vikdal, L. N.
Partner: UNT Libraries Government Documents Department

Summary report: laser candidates for inertial fusion

Description: During the period of mid-FY78 through early FY80, the DOE Office of Inertial Fusion (OIF) Advanced Laser Program transitioned from investigation at the small scale laboratory experiment level of several device candidates to a focus on scaling of related short wavelength systems, notably KrF. During this transition, WJSA performance under the above tasks provided responsive technical inputs to: (1) assist OIF in its comparative assessment of the initial candidates and selection of programs for further effort, (2) provide criteria for laser performance requirements necessary for reactor driver commercial feasibility, (3) project technology levels achievable as a function of time and resource investment, and (4) identify critical technical issues requiring resolution.
Date: January 1, 1980
Partner: UNT Libraries Government Documents Department

Intensification of rare gas halide lasers with application to laser fusion

Description: The two techniques of backward-wave Raman pulse compression and pulse stacking are reviewed in the context of using KrF lasers as drivers in inertial confinement fusion. Experimental and theoretical results on Raman pulse compression in methane are presented including data on 70 to 75% pump energy extraction by the counter propagating Stokes wave. Results from on-going pulse stacker/Raman compressor experiments are also described, along with future investigations in this general area.
Date: January 1, 1980
Creator: Jacobs, R.R.; Eimerl, D.; Goldhar, J.; Murray, J.R.; Rapoport, W.R.; Schlitt, L. et al.
Partner: UNT Libraries Government Documents Department

Development of CO/sub 2/ and KrF gas lasers as drivers for inertial confinement fusion

Description: Several different driver systems are currently under development in the national ICF program. Los Alamos has traditionally emphasized gas laser systems because of their intrinsic high average power capability and ease of operation. This paper will review the status of activities in both carbon dioxide (CO/sub 2/) and krypton fluoride (KrF) development at the Laboratory.
Date: January 1, 1983
Creator: Rockwood, S.D.
Partner: UNT Libraries Government Documents Department

Kinetics and spectroscopy of KrF (B) and Kr sub 2 F (4 sup 2. Gamma. )

Description: The absorption spectra corresponding to transitions from the 4{sup 2}{Gamma} level to upper excited states of several rare gas-halide trimers (Kr{sub 2}F, Ar{sub 2}F and Xe{sub 2}Cl) have been measured at wavelengths ranging from 200 nm to as large as 800 nm. Absolute absorption cross sections for Kr{sub 2}F have been determined. Experiments are discussed that will measure the radiative lifetime of the KrF (B) state which is formed utilizing a sub-picosecond source. KrF B {leftrightarrow} C mixing, quenching rates and the B{yields}X stimulated emission cross section will be measured. 21 refs., 6 figs., 1 tab.
Date: January 1, 1989
Creator: McCown, A.W. & Greene, D.P.
Partner: UNT Libraries Government Documents Department

Laser-damage thresholds of thin-film optical coatings at 248 nm

Description: We have measured the laser-induced damage thresholds for 248 nm wavelength light of over 100 optical coatings from commercial vendors and research institutions. All samples were irradiated once per damage site with temporally multi-lobed, 20-ns pulses generated by a KrF laser. The survey included high, partial, and dichroic reflectors, anti-reflective coatings, and single layer films. The samples were supplied by ten vendors. The majority of samples tested were high reflectors and antireflective coatings. The highest damage thresholds were 8.5 to 9.4 J/cm/sup 2/, respectively. Although these represent extremes of what has been tested so far, several vendors have produced coatings of both types with thresholds which consistently exceed 6 J/cm/sup 2/. Repeated irradiations of some sites were made on a few samples. These yielded no degradation in threshold, but in fact some improvement in damage resistance. These same samples also exhibited no change in threshold after being retested seven months later.
Date: December 11, 1981
Creator: Milam, D.; Rainer, F. & Lowdermilk, W.H.
Partner: UNT Libraries Government Documents Department

Kinetic modelling of krypton fluoride laser systems

Description: A kinetic model has been developed for the KrF* rare gas halide laser system, specifically for electron-beam pumped mixtures of krypton, fluorine, and either helium or argon. The excitation produced in the laser gas by the e-beam was calculated numerically using an algorithm checked by comparing the predicted ionization yields in the pure rare gases with their experimental values. The excitation of the laser media by multi-kilovolt x-rays was also modeled and shown to be similar to that produced by high energy electrons. A system of equations describing the transfer of the initial gas excitation into the laser upper level was assembled using reaction rate constants from both experiment and theory. A one-dimensional treatment of the interaction of the laser radiation with the gas was formulated which considered spontaneous and stimulated emission and absorption. The predictions of this model were in good agreement with the fluorescence signals and gain and absorption measured experimentally.
Date: November 1, 1983
Creator: Jancaitis, K.S.
Partner: UNT Libraries Government Documents Department

Pulse power for the RAPIER B Amplifier KrF laser system

Description: The RAPIER B Amplifier electron beam system has been completed and produces 36kJ of 450 keV electrons in a 150 ns pulse to be used for pumping a KrF laser amplifier. The operating characteristics of the system have been studied. The efficiency of conversion of energy stored in the Marx generator to electron beam output is 72 +- 3% including an 89% designed transfer efficiency. The system is triggered electrically with a 150 ns delay from the command trigger to machine output. The rms jitter for the six individual modules range from 1.6 to 3.9 ns and the average timing difference between the earliest and latest module output is 12 ns. Film dosimetry indicates no observable interaction between the magnetically isolated beams in the module diodes and fluorescence measurements do not indicate strong interaction in the gas filled laser cell. Current probe measurements show no significant change in beam size during the output pulse. Energy deposition profiles agree reasonably with Monte Carlo calculations up to pressures of 1.5 atm.
Date: May 25, 1983
Creator: Schlitt, L.G.
Partner: UNT Libraries Government Documents Department

Compact 36 kJ electron beam system for laser pumping

Description: An electron beam machine consisting of six modules is being constructed for the 'B' amplifier of the RAPIER KrF laser system. Each module consists of a diode, a 5 ..cap omega.. positive charged water dielectric Blumlein pulse-forming line, and a five stage Marx generator. Separate 25 cm x 41 cm electron beams are formed in magnetically isolated diodes which when arranged in groups of three produce two nearly continuous 25 cm x 125 cm beams that enter the laser cell from opposite sides. The pulse-forming lines operate at 450 keV and produce 150 ns long pulses. The lines employ electrically triggered annular SF/sub 6/ output switches. The two concentric transmission lines of each pulse-forming line are charged in 1 ..mu..s through symmetric circuits to reduce diode prepulse voltage. The six modules together with the laser cell will occupy less than 15 m/sup 2/ of floor space.
Date: May 31, 1981
Creator: Schlitt, L.G.
Partner: UNT Libraries Government Documents Department

Rare gas halide lasers for fusion. Final technical report, 1 March 1979-29 February 1980

Description: In an effort to reliably extend the understanding of KrF* lasers, we collected specific, detailed experimental data and carried out theoretical calculations to explore and document those issues we identified as likely to be important in the short pulse operating regime. These included the effects of: (1) fuel burnup, (2) electron quenching, (3) gain/absorption at high current densities, (4) photoionization, (5) accessibility of the lying levels of KrF by laser flux, (6) temperature on fluorescence efficiency.
Date: April 1, 1980
Creator: Duzy, C; Hsia, J; Hyman, H; Jacob, J; Klimek, D; Parks, J et al.
Partner: UNT Libraries Government Documents Department

Krypton fluoride laser mirror study. Final report, October 1978-November 1979

Description: Rare gas halide lasers at 193 and 248/nm will require lower-loss optics if mirrors ad windows are not to be limiting factors in advanced DOE applications in laser fusion and photochemistry. This project addresses this problem in a number of ways, including materials investigations, test coatings, and fabrication of new uv laser coating designs, as described in more detail in the previous quarterly reports. Described in the final report are the process of making uv laser mirrors and the experimental strategy for attempting to improve them. Materials research is essential, and included selection and deposition of several condidate materials and an approximate ranking of their optical properties, so that new material combinations could be chosen, computer simulated, and deposited using improved vacuum techniques. Analysis of the electric fields within a laser mirror were employed to lower coating loss. A summary of test data is included, along with remarks on the survivability of uv laser optics, and possible future areas of inquiry, if truly low-loss uv laser mirrors are to ever be developed.
Date: December 1, 1979
Creator: Flint, B.K.; Najmi, A. & Stelmack, L.A.
Partner: UNT Libraries Government Documents Department

Advanced lasers for fusion applications

Description: Projections indicate that MJ/MW laser systems, operating with efficiencies in escess of 1 percent, are required to drive laser fusion power reactors. Moreover, a premium in pellet performance is anticipated as the wavelength of the driver laser system is decreased. Short wavelength laser systems based on atomic selenium (lambda = 0.49..mu..), terbium molcular vapors (0.55..mu..), thulium doped dielectric solids (0.46..mu..), and on pulse compressions of KrF excimer laser radiaton (0.27..mu..) have been proposed and studied for this purpose. The technological scalability and efficiency of each of these systems is examined in this paper. All of these systems are projected to meet minimum systems requirements. Amont them, the pulse-compressed KrF system is projected to have the highest potential efficiency (6%) and the widest range of systems design options.
Date: November 1, 1978
Creator: Krupke, W.F.
Partner: UNT Libraries Government Documents Department

KrF-laser annealing of native oxides on GaAs

Description: Annealing of native oxides grown on GaAs has been performed using a pulsed KrF laser. This process allows the oxides to be heated to temperatures well above 350/sup 0/C without arsenic loss from the GaAs substrate. The physical, chemical, and electronic properties of the oxide are markedly changed by laser processing.
Date: January 1, 1980
Creator: Ahrenkiel, R.K.; Anderson, G.; Dunlavy, D.; Maggiore, C.; Hammond, R.B. & Stotlar, S.
Partner: UNT Libraries Government Documents Department

Time-resolved flourescence measurements of KrF emission produced by vacuum ultraviolet photolysis of KrF/sub 2/ mixtures

Description: Vacuum ultraviolet (VUV) light radiation was used to produce electronically excited KrF excimers (in D-, B- and C-states) by the photolysis of KrF/sub 2/ and F/sub 2//Kr mixtures at various excitation wavelengths. The excited KrF photoproduct quantum yield was measured over the excitation wavelength range of 120 to 200 nm, and a quantum efficiency of 0.45 was estimated at the peak absorption wavelength of 159 nm for KrF/sub 2/. The collision-free fluorescence lifetime of the B-X transition near 248 nm was determined to be 9.9 /plus minus/ 0.6 ns when the KrF/sub 2/ was excited with the 159 nm light. Near gas kinetic rate constants were measured for the quenching of KrF B-X emission by KrF/sub 2/ and CO/sub 2/. Using the threshold energy needed for observing excited KrF photofragments, an upper bound for the bond dissociation energy of KrF/sub 2/ was determined to be 1.03 /plus minus/ 0.1 eV. 14 refs., 8 figs.
Date: January 1, 1989
Creator: Tiee, J.J.; Quick, C.R.; Hsu, A.H. & Hof, D.E.
Partner: UNT Libraries Government Documents Department

Experimental investigation of the chemistry of excited states of rare gases. Annual technical progress report, October 15, 1976--October 14, 1977

Description: Tunable dye laser fluorescence has been combined with the flowing afterglow technique as a method for studying reactive intermediates present in the flowing afterglow. The radiative lifetimes and two-body quenching rate constants (with Ar carrier gas) for the Ar*(3p/sup 5/,4p) and Ar*(3p/sup 5/,5p) excited states were reported in the preceding year. During this year, we have measured the Ar* product states from the two-body quenching. More than 50% of the quenching leads directly to intermultiplet transfer to Ar(4s) states, rather than to intramultiplet cascade down the Ar(4p) manifold. Using this technique we also have studied the Xe(5p/sup 5/,6p') and Xe(5p/sup 5/,7p) excited states and radiative lifetimes, two-body quenching and the product states from quenching have been ascertained. These data should be of value for modeling energy flow pathways of rare gases excited by high energy electrons. A method has been developed for studying the quenching of the XeF(B) and KrF(B) by a variety of reagent molecules. A preliminary account of this work was published (number 5 in the publication list). Much additional experimental work has been done and a definitive study of the electronic quenching of XeF(B) and KrF(B) is in progress. Efforts to interpret (and publish) our comprehensive studies of the reactive quenching of the Kr(/sup 3/P/sub 2/) and Xe(/sup 3/P/sub 2/) by fluorine and chlorine-containing molecules has continued (see numbers 4, 6 and 8 in the publication listing). Two more manuscripts are in final stages of preparation. Of particular importance has been the development of methods for simulating and interpreting the bound-free emission spectra from the very high vibrational levels of the xenon and krypton fluorides and chlorides. Experiments have been done to measure the branching ratios for (i) ArF* formation from reactive quenching of Ar(/sup 3/P/sub 2/) with fluorine-containing reagents and (ii) KrBr* and Br* formation for ...
Date: January 1, 1978
Creator: Setser, D.W.
Partner: UNT Libraries Government Documents Department

850 J, 150 ns narrow-band krypton fluoride laser

Description: We report laser experiments on a 248 nm KrF laser with a 30x40x120 cm gain volume and an injection locked unstable resonator cavity. The volume is pumped by six 450 kV, 90 kA electron beam generators using water pulse forming lines.
Date: December 16, 1983
Creator: Goldhar, J.; Jancaitis, K.S.; Murray, J.R. & Schlitt, L.G.
Partner: UNT Libraries Government Documents Department

Alternate laser fusion drivers

Description: Over the past few years, several laser systems have been considered as possible laser fusion drivers. Recently, there has been an increasing effort to evaluate these systems in terms of a reactor driver application. The specifications for such a system have become firmer and generally more restrictive. Several of the promising candidates such as the group VI laser, the metal vapor excimers and some solid state lasers can be eliminated on the basis of inefficiency. New solid state systems may impact the long range development of a fusion driver. Of the short wavelength gas lasers, the KrF laser used in conjunction with Raman compression and pulse stacking techniques is the most promising approach. Efficiencies approaching 10% may be possible with this system. While technically feasible, these approaches are complex and costly and are unsatisfying in an aethetic sense. A search for new lasers with more compelling features is still needed.
Date: November 1, 1979
Creator: Pleasance, L.D.
Partner: UNT Libraries Government Documents Department

Time-resolved reflectivity measurements of silicon and germanium pulsed excimer laser irradiation

Description: Time-resolved reflectivity measurements of silicon and germanium have been made during pulsed KrF excimer laser irradiation. The reflectivity was measured simultaneously at both 1152 and 632.8 nm wavelengths, and the energy density of each laser pulse was monitored. The melt duration and the time of the onset of melting were measured and compared with the results of melting model calculations. For energy densities just above the melting threshold, it was found that the melt duration was never less than 20 ns for Si and 25 ns for Ge, while the maximum reflectivity increased from the value of the hot solid to that of the liquid over a finite energy range. These results, along with a reinterpretation of earlier time-resolved ellipsometry measurements, indicates that, during the melt-in process, the near-surface region does not melt homogeneously, but rather consists of a mixture of solid and liquid phases. The reflectivity at the onset of melting and in the liquid phase have been measured at both 632.8 and 1152 nm, and are compared with the results found in the literature.
Date: November 1, 1985
Creator: Jellison, G.E. Jr.; Lowndes, D.H.; Mashburn, D.N. & Wood, R.F.
Partner: UNT Libraries Government Documents Department