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Far infrared chemical lasers. Technical progress report No. 5, September 1, 1978-August 31, 1979

Description: The intention to use the optically-pumped water vapor laser to study energy absorption and transfer in this triatomic molecule was not realized. The system at this moment is not well-enough understood to be as useful as was originally anticipated. What is known is that laser action in the far infrared is the result of flash-pumping, through suprasil, water vapor in the 10-100 mtorr pressure range, in a large resonator. About ten lines at about 100-200 cm/sup -1/ have been found. Four of them very definitely can be assigned to transitions that evolve from the feeding of the level (001)6/sub 42/. The other lines are of dubious assignment or completely unassignable. All of the hundred or so lines of well-known water discharge laser have been assigned to places in the level scheme where the bend-stretch wave functions are mixed.
Date: January 1, 1979
Creator: Robinson, D. W.
Partner: UNT Libraries Government Documents Department

Investigation of efficiency optimization in free electron lasers

Description: The dynamics of trapped particles in the presence of the wiggler magnetic field and the electromagnetic radiation field in free electron lasers were investigated. From the results of computer simulations, it was found that, for a given set of parameters, the efficiency of energy extraction from the electron beam maximizes at a particular intensity of the electromagnetic radiation. Based on the physical argument of the dynamics of the trapped particles, a criterion which predicts accurately the optimum intensity of the electromagnetic radiation was obtained. (TFD)
Date: January 1, 1979
Creator: Kwan, T.J.T.
Partner: UNT Libraries Government Documents Department

Layered target burnthrough experiments using 50 nsec KrF laser pulses

Description: Experiments have been performed on two types of planar layered targets using the Sprite KrF laser. The targets lused were: (1) 0.25 to 3.0 microns of Al deposited on an SiO/sub 2/ substrate and (2) 0.25 to 3.0 microns of CH (parylene-N) deposited on 0.20 microns of Al on an SiO/sub 2/ substrate. The laser was characterized by a pulse length of 50 nsec FWHM, an intensity of 2 x 10/sup 10/ watts/cm/sup 2/ and a wavelength of 248.5 nm. A filtered photoiodide and a streak camera, each operating in the visible, viewed the rear of the target. We measured the time from the beginning of the laser pulse to the onset of the visible light signal as seen by the photoiodide at the rear of the initially opaque target. This time is referred to as the burnthrough time. We obtain an estimate of the mass ablation by plotting the mass ablation depth (mass density times target thickness in ..mu..gm/cm/sup 2/) versus the burnthrough time. These results are consistent with earlier mass loss measurements and with analytic and hydro-code calculations (LASNEX). The streak camera data shows emission at target positions larger than the laser focal spot, and thus are consistent with 1-D and 2-D calculations which show target surface ablation to be primarily driven by reradiated photons from the hot laser produced plasma.
Date: January 1, 1986
Creator: Kephart, J.F.; Dingus, R.S.; Gitomer, S.J.; Kopp, R.A. & Shaw, M.J.
Partner: UNT Libraries Government Documents Department

Scalable nanosecond CO/sub 2/ laser technology. Progress report for period November 7, 1976--January 7, 1977

Description: This second bi-monthly progress report on the Scalable Nanosecond CO/sub 2/ Laser Technology Program covers work performed from November 8, 1976 to January 7, 1977. Under Task I - Saturable Absorber Studies, small signal absorption measurements over the 9 and 10 ..mu.. bands were carried out on various molecules to determine their potential as gain isolators. Saturation and relaxation experiments are being set-up to further evaluate some of these absorber media. Continued modeling and theoretical analyses of saturable absorber media under Task II - Theoretical Studies are providing the necessary inputs in the selection of various molecules. Under Task III - Flowing Saturable Absorber Device, the flow-field structure of gain and absorber regions was studied. A species concentration probe is being built to determine the amount of contamination of the gain medium by saturable absorber medium due to mass diffusion in the mixing layer. The nanosecond CO/sub 2/ oscillator is being readied under Task IV - Nanosecond CO/sub 2/ Oscillator to conduct saturation experiments of candidate saturable absorber media under both single and multi-line conditions.
Date: February 1, 1977
Partner: UNT Libraries Government Documents Department

Stable 1 --> 0 carbon monoxide laser

Description: A stable carbon monoxide laser capable of oscillation on transitions in the fundamental 1 ..-->.. 0 band is described. This laser is also capable of a quasi-continuous tunability in the range of 4.7 to 8 microns.
Date: July 1, 1978
Creator: Gerlach, R. & Amer, N.M.
Partner: UNT Libraries Government Documents Department

Review of long-pulse laser development

Description: A brief review of some present techniques to obtain long-pulse laser action in excimer discharge devices will be presented. An attempt will be made to point out the strengths and weaknesses of these techniques. 18 refs., 15 figs.
Date: January 1, 1989
Creator: Sze, R.C.
Partner: UNT Libraries Government Documents Department

Gas laser cells: stress analysis of cylindrical cells with radial injection of electrons

Description: The problem is to develop a design procedure for pressurized cylindrical excimer laser cells. Excitation of the pressurized laser gas is by a short pulse of high energy electrons injected through the cell wall. In traversing the wall, the electrons lose energy and heat the wall. Because of rapid gas heating, a shock wave is generated which produces an additional load on the wall. Selected for analysis is a simple, conservative model of a cylindrical cell pressurized to double the shock pressure. The hoop stress is given by the product of a coefficient, which accounts for the shock over pressure, and the classical hoop stress relation. The shock over pressure coefficient is linearly related to the volumetric energy deposition with slope inversely proportional to the product of initial gas density, specific heat, and temperature. The derived equation is applied to a design study of a selected range of laser parameters. The applicability of this simple analysis is discussed. Electron energy absorption curves for several metals are also presented.
Date: February 14, 1975
Creator: Lai, W.
Partner: UNT Libraries Government Documents Department

Progress toward free-electron lasers for applications

Description: Using an electron beam in a magnetic field as the gain medium, free-electron lasers offer a powerful new source of tunable, coherent radiation. Results are just becoming available from several new experiments, but they are confirming the theoretical promise of these devices. Backed up by a strong base of accelerator technology, free-electron lasers are expected to become important in applications requiring wavelengths from the far infrared part of the spectrum to the vacuum ultraviolet.
Date: January 1, 1984
Creator: Brau, C.A.
Partner: UNT Libraries Government Documents Department

Narrow band tuning with small long pulse excimer lasers

Description: We discuss frequency narrowing and tuning with simple dispersion elements with small long-pulse excimer lasers. The improved performance over short-pulse lasers is discussed and attributed to the increased number of round trips. A physical model of the dynamics of line narrowing is presented.
Date: December 1, 1985
Creator: Sze, R.C.; Kurnit, N.; Watkins, D. & Bigio, I.
Partner: UNT Libraries Government Documents Department

Evolution of free-electron laser development

Description: Recent experimental demonstrations of free-electron laser oscillators and amplifiers have verified the feasibility of these broadly tunable photon sources. We review the current status and their continuing evolution toward ever higher output power and shorter wavelengths. 46 refs.
Date: January 1, 1986
Creator: Newman, B.E.
Partner: UNT Libraries Government Documents Department

Free electron lasers

Description: A review of experimental and theoretical concepts of a free electron laser is given. The possibilities of scaling these lasers to high powers are discussed. (MOW)
Date: January 1, 1980
Creator: Brau, C.A.
Partner: UNT Libraries Government Documents Department

Laser-based instrumentation for detection of chemical-warfare agents

Description: Several laser-based techniques are being developed for remote, point, and surface contamination detection of chemical warfare agents. These techniques include optoacoustic spectroscopy, laser-induced breakdown spectroscopy, and synchronous detection of laser-induced fluorescence. Detection limits in the part-per-million to part-per-billion regime have been demonstrated.
Date: January 1, 1981
Creator: Quigley, G.P.; Radziemski, L.J.; Sander, R.K. & Hartford, A. Jr.
Partner: UNT Libraries Government Documents Department

Low-pressure approach to the formation and study of exciplex systems. Progress report

Description: Continued fundamental studies are proposed on both the formation and properties of new materials for high-energy, gas-phase lasers. As originally proposed, attention will be focused mainly (but not wholly) on systems which have bound excited states but unbound ground states. An important class of such excimer/exciplex systems has a van der Waals dimer/oligomer as its ground state. In the original proposal for this work, a new method for the preparation of excimers and exciplexes was presented in which van der Waals complexes are formed as intermediates. Systems under study include the excited states of dimers, oxides and halides of inert gases.
Date: August 23, 1976
Creator: Sanzone, G.
Partner: UNT Libraries Government Documents Department

Status of the Los Alamos Free-Electron Laser

Description: Since the initial oscillator experiments were completed last year, the Los Alamos FEL has undergone some major modifications and additions in preparation for the next set of experiments. The laser performance is projected to be substantially enhanced, the rf energy-recovery technique will be demonstrated, and FEL physics measurements will be expanded. The accelerator is now being tuned with very promising performance. The above experiments will be completed during the next year.
Date: January 1, 1985
Creator: Watson, J.M.
Partner: UNT Libraries Government Documents Department

Reinjection laser oscillator and method

Description: A uv preionized CO/sub 2/ oscillator with integral four-pass amplifier capable of providing 1 to 5 GW laser pulses with pulse widths from 0.1 to 0.5 ns full width at half-maximum (FWHM) is described. The apparatus is operated at any pressure from 1 atm to 10 atm without the necessity of complex high voltage electronics. The reinjection technique employed gives rise to a compact, efficient system that is particularly immune to alignment instabilities with a minimal amount of hardware and complexity.
Date: August 20, 1981
Creator: McLellan, E.J.
Partner: UNT Libraries Government Documents Department

Bibliography of GRASER research. Informal report

Description: The bibliography contains 161 references to literature on the problem of developing gamma-ray lasers or of observing stimulated emission or coherent spontaneous emission of nuclear gamma radiation, together with a number of references that deal with phenomena that are expected to be central to their realization. The period covered is 1917 through 1979.
Date: April 1, 1979
Creator: Baldwin, G.C.
Partner: UNT Libraries Government Documents Department

Status of the free-electron laser experiment at Los Alamos

Description: Main design parameters are presented for the accelerator, the laser, and the wiggler. Four sections are presented that discuss unusual or different features in the design, construction, alignment, and diagnostic parts of the experiment. Up-to-date performance characteristics of the components are described. (MOW)
Date: January 1, 1981
Creator: Warren, R.W.; Brau, C.A.; Newnam, B.E.; Stein, W.E.; Winston, J.G. & Young, L.M.
Partner: UNT Libraries Government Documents Department

Evaluation of bidirectionally conducting thyratrons for pulsed excimer lasers

Description: In the last few years many new applications have been found for excimer lasers in industry and defense programs. Many of these programs have very stringent requirements of lifetime, reliability, and power that are not available commercially. Power conditioning systems capable of driving excimers with reliable lifetimes of 5 billion pulses have been built with off-the-shelf components. In this paper we will discuss the requirements and life test performance of three types of thyratrons designed specifically for driving excimer lasers and also the life of associated components.
Date: January 1, 1984
Creator: McDuff, G.; Rust, K.; Menown, H. & Neale, C.
Partner: UNT Libraries Government Documents Department

Advanced electrooptic components for satellite/submarine optical communications systems

Description: Significant progress was made on identification and acquisition of optical components for an ultrahigh brightness weakly tunable blue-green beam generator. Limited performance validation of key system design concepts was achieved, and significant progress was made in improved optical design for more efficient generation of ultrahigh brightness, tunable blue-green radiation. These results are detailed.
Date: September 30, 1976
Creator: Marling, J. B.; Aldridge, F. T. & Wood, L. L.
Partner: UNT Libraries Government Documents Department

Halide laser glasses

Description: Energy storage and energy extraction are of prime importance for efficient laser action and are affected by the line strengths and linewidths of optical transitions, excited-state lifetimes, nonradiative decay processes, spectroscopic inhomogeneities, nonlinear refractive index, and damage threshold. These properties are all host dependent. To illustrate this, the spectroscopic properties of Nd/sup 3 +/ have been measured in numerous oxide, oxyhalide, and halide glasses. A table summarizes the reported ranges of stimulated emission cross sections, peak wavelengths, linewidths, and radiative lifetimes associated with the /sup 4/F/sub 3/2/ ..-->.. /sup 4/I/sub 11/2/ lasing transition.
Date: January 14, 1982
Creator: Weber, M.J.
Partner: UNT Libraries Government Documents Department

Additive enhancement of short pulse flashlamps

Description: A key factor in the development of iodine photodisassociation lasers is the improvement of pump lamp efficiency in the 250 to 300 nm pump band at pulsewidths of about 10 ..mu..s. Previous work by Gusinow showed that certain metal additives appeared to enhance pump lamp output in the 250 to 300 nm region by as much as a factor of three. This had been determined by comparing microdensitometer traces of spectrograms of doped and undoped lamps. The principal problems noted with these lamps were a shot-to-shot variability of more than 30% and an effective life of only 20 shots (a result of migration of the dopants from between the electrodes to the colder regions behind the electrodes).
Date: April 1, 1977
Creator: Shaw, J. F.; Maynard, R. & Lovoi, P.
Partner: UNT Libraries Government Documents Department

Metal vapor excimer laser. Quarterly progress report, May 1, 1978--July 31, 1978

Description: The discharge tube and circuitry has been assembled and tested and awaits the addition of metal vapor for the first discharge and gain tests. Further problems with the discharge tube as a result of high voltage arcing were encountered and finally overcome. Materials testing with cadmium has demonstrated that stainless steel and Inconel are suitable for fabrication materials while Monel is not. An investigation of scaling considerations of a single pulse metal vapor laser system was initiated and some preliminary assessments are detailed below. Inverse Bremsstrahlung pumping of a metal vapor system is discussed as a possible alternate to a conventional e-beam stabilized discharge.
Date: October 1, 1978
Creator: Kovacs, M.A. & Jacob, J.H.
Partner: UNT Libraries Government Documents Department