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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

Damage history of Argus, a 4TW Nd-glass system

Description: Argus is a twin beam, 20 cm output aperture, Nd:glass laser system that has delivered 4TW to a laser fusion target. This performance is based on the concepts that multiple spatial filtering can prevent beam fill factors. Damage to optics due to self focusing and filamentation does not occur on Argus. The only form of damage is induced by broadband radiation from xenon flashlamps interacting with contaminants on or in the Nd:glass. The severity of damage is measured by the fraction of the beam obscured by the damage sites. This averages 0.1% per surface or 0.75% per arm. The amount of damage does not appear to be strongly related to the number of amplifier firings and generally occurs during the first few firings.
Date: December 6, 1977
Creator: Stowers, I.F. & Patton, H.G.
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

Development of an actively modelocked and Q-switched oscillator for laser fusion program at LLL

Description: A method was developed that allows the mode-locking process to go to its steady state condition before the laser is Q-switched. This is done by pumping the laser quasi-cw for about 5 ms. During this time, the loss in the Q-switch is such that the laser will just slightly go above threshold. The active modulator is on during this time, and the laser oscillates quasi-cw for a period long enough to obtain stable transform-limited short pulses. At the end of this prelase period, the laser is Q-switched, and a train of stable, short pulses is obtained.
Date: July 19, 1978
Creator: Kuizenga, D.J.
Partner: UNT Libraries Government Documents Department

Janus neodymium glass laser operations manual

Description: A manual, prepared to guide personnel in operating and maintaining the Janus glass laser system, is presented. System components are described in detail. Step-by-step procedures are presented for firing the laser and for performing routine maintenance and calibration procedures.
Date: September 29, 1978
Creator: Auerbach, J.M.; Holmes, N.C. & Trainor, R.J.
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

Metal vapor excimer laser. Quarterly progress report, August 1, 1978--October 31, 1978

Description: Progress in the metal vapor excimer program was slowed in the quarter as a result of a fire which occurred in the apparatus. As this period closed, the fire related damage had largely been repaired; in spite of the setback there will be sufficient time to generate data for the mid-December workshop meeting. Initial design considerations for the foil and foil support of a high temperature, transverse e-beam discharge device have been generated. In addition, foil material testing has been performed.
Date: December 1, 1978
Creator: Kovacs, M.A. & Jacob, J.H.
Partner: UNT Libraries Government Documents Department

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

Overvoltage protection by point-plane spark gaps

Description: In electron-beam-controlled discharge CO/sup 2/ lasers, such as those used in the Antares and Helios laser-fusion drivers at the Los Alamos Scientific Laboratory (LASL), protection needs to be provided against possible damage due to overvoltage. A passive (self-breakdown) point-plane spark gap has been developed and successfully used in the Helios power amplifiers which operate at voltages up to 300 kV. A gap of similar design is planned for use in the Antares power amplifiers which operate at 550 kV. These gaps must reliably hold off the normal discharge voltage, but break down with short delay if overvoltaged, diverting the discharge energy to a resistor. A prototype of the Antares gap has been built and is undergoing tests. Parameters being investigated include voltage polarity, gap spacing, gas composition, and gas pressure. Results of these measurements and the operational experience of the Helios gaps will be presented.
Date: January 1, 1979
Creator: Scarlett, W.R. & Riepe, K.B.
Partner: UNT Libraries Government Documents Department

Research on frequency shifting of ultraviolet lasers. Final report, June 23, 1977--May 23, 1978

Description: The four-wave mixing interaction proposed for uv frequency shifting cannot be phase matched with known techniques. One related process that avoids phase matching problems is stimulated Raman scattering (SRS). The same wavelength generated by four-wave mixing (2821 A) could also be generated by SRS using the uv pump source alone. In this case, the uv pump power must be high enough to exceed the oscillation threshold. SRS was observed in liquid CO pumped by the doubled Nd:YAG laser at 5320 A. The quadrupled Nd:YAG pump power at 2660 A was insufficient to attain SRS threshold. Although high-efficiency SRS should be attainable in the uv with more pump power, it is unlikely that this process can compete with frequency shifting of a KrF laser by SRS in hydrogen. The materials examined for Raman shifting of 10 ..mu..m lasers show promise for efficient energy conversion to the 16..mu..m region. However, a more quantitative evaluation must await further data on Raman cross section and linewidth. In the case of fibers, some further materials development work is also required.
Date: January 1, 1979
Creator: Klein, M B
Partner: UNT Libraries Government Documents Department

Preliminary examination of the Linear Free-Electron Laser

Description: The Linear Free Electron Laser is numerically analyzed in the one dimensional limit by following an average (resonant) particle. Several different wiggler schemes are presented, and electron beam current density requirements are discussed. A variable phase angle buncher is also proposed.
Date: February 5, 1979
Creator: Prosnitz, D. & Szoke, A.
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

Laser materials: July 1, 1977-July 31, 1978

Description: Fluoride materials display specific properties applicable for use as active and passive optical elements for advanced laser programs. Generally, these materials exhibit low values of n/sub 2/ and high ultraviolet transmission. Nd:YLF is a very promising laser fusion oscillator element operating in conjunction with phosphate and fluoroberyllate systems. New materials possessing high concentrations of terbium and cerium - KTb/sub 3/F/sub 10/, RbTb/sub 3/F/sub 10/ and potassium cerium compounds, display high magneto-optical rotatory power, high Verdet's constant, for use as Faraday rotators. Nd:YLF, operating at 1.047 ..mu..m or 1.053 ..mu..m has been identified as the most promising oscillator material for phosphate and fluoroberyllate systems. The new materials investigation included crystal growth and phase study of KTb/sub 3/F/sub 10/. KTb/sub 3/F/sub 10/ displays one of the highest figures of merit of any known material. Preliminary growth studies of other potential rotator materials included the RbF-Tb/sub 3/F/sub 10/ and the KF-CeF/sub 3/ systems. Compounds of both systems are expected to display high Verdet's constants.
Date: August 8, 1979
Creator: Folweiler, R.C.
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

Small-signal-gain spectrum of an 1800 Torr CO/sub 2/ amplifier

Description: Prominent hot-band effects have been observed in the 9.4 and 10.6 ..mu..m gain spectrum of an 1800 Torr electron-beam-controlled-discharge CO/sub 2/ laser amplifier. The data are in good agreement with theoretical calculations at 53 different frequencies.
Date: January 1, 1981
Creator: Goldstein, J.C.; Haglund, R.F. Jr. & Comly, J.C. Jr.
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

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

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

First operation of the Los Alamos free-electron laser oscillator

Description: An FEL oscillator has been operated at wavelengths between 9 and 11 ..mu..m with a peak intracavity power of about 20 MW and an average output power of 1 kW in 70- ..mu..s pulses. We present the design parameters and operating characteristics. We report measurements of spontaneous emission, start-up of oscillations, and signal growth through approx. 9 orders of magnitude to saturation. The dependence of gain and saturation on cavity length, alignment, beam parameters, and other critical variables are discussed and compared with theory. 7 references.
Date: January 1, 1983
Creator: Warren, R.W.; Newnam, B.E.; Stein, W.E.; Winston, J.G.; Sheffield, R.L.; Lynch, M.T. et al.
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

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