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Compact resistively stablized excimer laser for injection- and mode-locking applications

Description: A miniature, resistively-stabilized excimer laser has been developed. The laser has 86 separately stabilized discharges within a length of only 27.6 cm, which allows for a total cavity length of only 33 cm. Presently, with a 2.5-mm electrode separation, we have obtained over 1 mJ per pulse energy in XeCl and the laser has been operated over 70 Hz without gas flow. Pulse lengths as long as 40 ns full-width at half-maximum intensity and over 80 ns total lasing time has been observed. The beam divergence is measured at three times the diffraction limit. This laser is expected to be uniquely suited for injection-locking and mode-locking applications.
Date: January 1, 1982
Creator: Sze, R.C.
Partner: UNT Libraries Government Documents Department

Excimer laser chemical problems

Description: Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.
Date: January 1, 1982
Creator: Tennant, R. & Peterson, N.
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

Excimer laser chemical problems

Description: Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.
Date: January 1, 1982
Creator: Tennant, R. & Peterson, N.
Partner: UNT Libraries Government Documents Department

High power laser and materials investigation. Final report, 31 July 1978-28 October 1979

Description: This is a combined study of resonant pumped solid state lasers as fusion drivers, and the development of crystalline optical materials suitable for propagation of the high peak powers associated with laser fusion research. During this period of study the concept of rare gas halide lasers was first demonstrated by the lasing of Tm:YLF at 453 nm pumped by the 353 nm energy of XeF. Excited stata densities of 5 x 10/sup 18/ cm/sup -3/ have been attained and spectroscopic measurements show that up to 60% of the pump energy can be converted into useful stored energy. Alternative lasers and pumping schemes are also discussed. In all cases the potential RGH/SS systems are evaluated in respect to internal efficiency and heat loading.
Date: June 1, 1980
Creator: Chicklis, E.P.; Folweiler, R.C.; Pollak, T.M. & Baer, J.
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

Transform-limited-bandwidth injection locking of an XeF laser

Description: A pulsed Ar-ion laser, operating on the 3511 A line of the doubly ionized species, has been used to injection lock an unstable resonator XeF laser. A single longitudinal mode of the Ar-ion laser was selected with a Fabry-Perot etalon, and the resulting XeF bandwidth was measured to be approx. 50 MHz which is the Fourier-transform limit corresponding to the XeF laser pulse duration of approx. 20 ns. Since the XeF B ..-->.. X emission originates from more than one upper vibrational level, for this pulse duration it was determined that approx. 60% of the total output was available to be locked to the reference oscillator line. The 2 MW output beam was also found to be near (< 1.5 x) diffraction limited.
Date: January 1, 1982
Creator: Bigio, I.J. & Slatkine, M.
Partner: UNT Libraries Government Documents Department

Overview of recent advances in excimer laser technology at Los Alamos

Description: From among the areas of excimer laser development at Los Alamos two are selected for further discussion: ultra-high brightness excimer laser systems and discharge-pumped XeF(C..-->..A) lasers operating in the blue-green portion of the spectrum. Two different high brightness systems are described. One is based on small-aperture KrF amplifiers, while the other is based on a large-aperture XeCl amplifier. The XeF(C..-->..A) laser is tunable from 435 to 525 nm, and may one day become a viable alternative to pulsed dye lasers for many applications. 14 refs., 4 figs.
Date: January 1, 1988
Creator: Bigio, I.J.; Sze, R.C.; Taylor, A.J. & Gibson, R.B.
Partner: UNT Libraries Government Documents Department

Inductively stabilized excimer lasers

Description: The technique of inductive stabilization of rare-gas halide discharges have been shown to yield long pulse laser outputs. The 1% efficiency obtained for the miniature short pulsed devices are believed to be very good. Length scaling to improve the gain per round trip of the laser cavity should improve the peak power in the cavity and greatly improve the extraction efficiency. This work is presently in progress. The measurement of a saturation energy for electrical energy deposition gives an important design criteria for high efficiency lasers. This number is believed to be valid regardless of the time scale of the energy deposition.
Date: December 1, 1983
Creator: Sze, R.C.
Partner: UNT Libraries Government Documents Department

Theoretical modeling of the KrF fluorescence spectrum

Description: Dunning's amd Hay's electronic potential curves were used to compute transition moments and to predict emission profiles for comparison with the observed fluorescence spectra. By adjusting the ionic and valence states by 8 nm, many of the observed spectral features can be quantitatively accounted for. The synthetic spectrum of KrF includes the 220-nm D/sub /sup 1///sub 2// ..-->.. X transition, the 249-nm composite feature, and the 276-nm feature which is a superposition of the nearly coincident C/sub /sup 3///sub 2// ..-->.. A/sub /sup 3///sub 2// and B/sub /sup 1///sub 2// ..-->.. /sub /sup 1///sub 2// transitions. The feature observed at 300 nm by Powell and Murray is likely due to a transition from the /sup 2/..sigma../sup +//sub /sup 1///sub 2// Rydberg state to the repulsive A/sub /sup 1///sub 2// state. The 400-nm feature may be due to a triatomic complex. (DLC)
Date: September 10, 1976
Creator: Rescigno, T. N. & Winter, N. W.
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

Experimental investigation of the chemistry of excited states of rare gases. Third quarterly progress report, April 15, 1978--July 15, 1978

Description: The quenching of XeF(B) was studied by using the steady-state photolysis of XeF/sub 2/ as the source of XeF(B). The XeF(C) state was observed, as well as the XeF(B) state, by using a very clean CO(A-X) resonance lamp to photolyze the XeF/sub 2/. XeF(C) must be included in the kinetic scheme in order to understand the quenching of XeF*. The preliminary work that has been done with the Xe(/sup 3/P/sub 1/) and Kr(/sup 3/P/sub 1/) resonance atom reactions is summarized. The pulsed laser induced fluorescence technique was used to measure radiative lifetimes and two-body quenching rate constants. The study of Ne(3p)** in Ne Buffer has been completed and tables of these results are included. Some exploratory work searching for new emission spectra and with an emphasis on rare gas oxide spectra has been done and is described.
Date: July 1, 1978
Creator: Setser, D.W.
Partner: UNT Libraries Government Documents Department

XeF pump laser. Final technical report

Description: The goal of this program was to demonstrate operation of an XeF laser of adequate energy, efficiency and beam quality at high repetition rates. The specific design goals were: PRF greater than or equal to 10 kHz, energy output greater than or equal to 50 mJ/pulse, efficiency greater than or equal to 0.3%, and beam divergence angle less than or equal to 20x diffraction limited. In the following sections of this report we will discuss how these goals have been met.
Date: March 1, 1980
Partner: UNT Libraries Government Documents Department

Conceptual design of a 1. 5-MJ, 2-Hz KrF fusion laser system

Description: The report consists of two major elements: Section II presents an overview of the design study and discusses the major results and conclusions derived from this study; and Section III provides details of the technical analyses and results and presents technical summaries that discuss e-beam pulsed-power conditioning, optical-system design, mechanical-systems design, facilities, overall laser-system efficiency, and capital costs.
Date: December 1, 1980
Creator: Caird, J.; Allen, W.O. & Hipkin, H.G.
Partner: UNT Libraries Government Documents Department

Fluid mechanics of fusion lasers. Final report, September 11, 1978-June 5, 1980

Description: Flow loop components required to operate continuous-flow, repetitively-pulsed CO/sub 2/ and KrF laser drivers for ICF were identified and their performance requirements were specified. It was found that the laser flow loops can have a major effect on the laser beam quality and overall efficiency. The pressure wave suppressor was identified as the most critical flow loop component. The performance of vented side-wall suppressors was evaluated both analytically and experimentally and found capable of meeting the performance requirements of the CO/sub 2/ and KrF fusion lasers. All other laser flow loop components are essentially similar to those used in conventional, low speed wind tunnels and are therefore well characterized and can be readily incorporated into fusion laser flow systems designs.
Date: January 1, 1980
Creator: Shwartz, J; Kulkarny, V A; Ausherman, D A; Legner, H H & Sturtevant, B
Partner: UNT Libraries Government Documents Department

Metal vapor Raman compressor. Final report, April 1, 1979-March 31, 1980

Description: The objectives of the present work were to demonstrate the feasibility of a long Pb vapor cell and to assess the potential of the XeCl-Pb system as a Raman pulse compressor. For this work, a narrow bandwidth XeCl laser was developed and an 8 m Pb vapor cell was constructed. Details on the laser device and the results of the experiment are given.
Date: January 1, 1980
Partner: UNT Libraries Government Documents Department

Synthesis and characterization of graphite-metal fluoride intercalation compounds

Description: The compound C/sub x/AsF/sub 5/ was prepared and characterized by x-ray diffraction and x-ray absorption, which show the presence of As(III) and As(V), and the As-F bond distances are consistent with AsF/sub 3/ and AsF/sup -//sub 6/, C/sup +//sub 8/AsF/sup -//sub 6/ and C/sup +//sub 8/OsF/sup -//sub 6/ were synthesized. The C/sub x/AsF/sub 6/ and numerous standard arsenic-flourine compounds were studied by x-ray absorption. Magnetic susceptibility of C/sup +//sub 8/OsF/sup -//sub 6/ confirms the high degree of oxidation in this compound. X-ray absorption studies were begun to determine the species present within the graphite when BrF/sub 3/ or GeF/sub 4/ + F/sub 2/ are added. In the BrF/sub 3/ case, Br/sub 2/ is evolved and only Br(III) is present in the graphite. The binary phase diagram XeF/sub 2/:Xe/sup +//sub 5/AsF/sup -//sub 6/ was investigated by melting point determination and Raman spectroscopy. This mixture near 1.3:1 forms a kinetically stable glass at room temperature and is molten at 50/sup 0/C. Several new species or phases are observed in the Raman spectra. These species have been assigned tentative structures.
Date: April 1, 1981
Creator: McQuillan, B.W.
Partner: UNT Libraries Government Documents Department

Discharge physics, formation and quenching processes of XeF. Final technical report

Description: Discharge physics and the formation and quenching processes in typical XeF laser mixtures are discussed. We have determined that the discharge physics is dominated by electron impact excitation and ionization of the rare gas metastables. The ionization of the metastables impacts the discharge stability directly while their excitation strongly affects the efficiency of producing XeF*. From our discharge experiments we have determined that Xe/sup +/(6p) states react with NF/sub 3/ to produce XeF* with a branching ratio of 0.7. The rate constant for this reaction is 4 x 10/sup -10/ cm/sup 3//sec. The formation and quenching processes have been determined by analyzing the dependence of (B/sup 2/..sigma../sup +//sub 1/2/ ..-->.. X/sup 3/..sigma../sup +//sub 1/2/) radiation on the partial pressures of Ar, Xe, and F/sub 2/. In the experiments the XeF* was produced by a high energy E-beam. We have determined the two and three body quenching rates by Ar to be 8 +- 4 x 10/sup -13/ cm/sup 3//sec and 1.5 +- 0.5 x 10/sup -32/ cm/sup 6//sec. Xe quenches XeF* with a three body rate of 3 +- 1.5 x 10/sup -31/ cm/sup 6//sec; the third body was mainly argon.
Date: May 1, 1977
Partner: UNT Libraries Government Documents Department

Efficient forward conversion in a Raman generator

Description: Stimulated Raman scattering of an XeCl laser at 308 nm in a high pressure H/sub 2/ cell shows anomalously high conversion into first Stokes (S1) when a pumping geometry with a Fresnel number near unity is used. Specifically a quantum efficiency of 88% is obtained into S1. Comparison with a plane-wave model indicates that a theory including diffraction and 4-wave mixing may be necessary to understand the anomalous holdoff of the second Stokes component. 10 references.
Date: January 1, 1984
Creator: Carlsten, J.L.; Telle, J.M. & Wenzel, R.G.
Partner: UNT Libraries Government Documents Department

E-beam-induced fluorescence of excimers in cryogenic solutions

Description: We have detected the fluorescence emitted from excimer molecules formed in e-beam-pumped mixtures in a liquid argon host. The mixtures were both binary (halogen donors in the liquid argon) and ternary (dilute concentrations of donors and other rare gases in the liquid argon). Many excimers were observed, including the rare-gas dimers Xe/sub 2/, Kr/sub 2/, and Ar/sub 2/. Strong fluorescence was seen from XeF, XeCl, and ArO.
Date: January 1, 1985
Creator: Loree, T.R.; Showalter, R.R.; Johnson, T.M.; Telle, J.M.; Fisher, R.A. & Hughes, W.M.
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