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Intracavity flux dependent absorption in e-beam pumped KrF

Description: Transient absorption measurements are performed on e-beam excited KrF under lasing and nonlasing conditions for 10% Kr (Ar diluent) and 99.6% Kr gas mixtures. The intracavity flux is varied by changing the output mirror reflectivity. The deposition rate for this experiment is {approx}396 kW/cm{sup 3}. For the 10% Kr and Kr-rich mixtures, the small signal absorption at 248.4 nm is 0.76%/cm and 1.25%/cm, respectively; while the nonsaturable absorption in 0.62%/cm and 0.90%/cm, respectively. A flux loading of {approx}1.5 MW/cm{sup 2} is needed to achieve nearly complete saturation of the saturable absorption.
Date: December 31, 1988
Creator: Seamans, J. F.; Kimura, W. D. & Hanson, D. E.
Partner: UNT Libraries Government Documents Department

Characteristics of the 2.65 {mu}m atomic xenon laser

Description: The laser characteristics of the 2.65 {mu}m xenon laser transition are reviewed. Measured and extrapolated laser efficiency in nuclear pumped and electron beam pumped system is reported. Previous research has indicated that the reported power efficiency is between 0.1 and 2 percent.
Date: October 1, 1995
Creator: Hebner, G.A.
Partner: UNT Libraries Government Documents Department

Multi-kiloampere, electron-beam generation using metal photo-cathodes driven by ArF and KrF lasers

Description: An electron-beam-pumped laser operating at ArF (193 nm) or KrF (248 nm) producing 35 MW (3.5 J in 100 ns) has been used to illuminate a micro-machined aluminum cathode. The cathode was pulsed to 2.75 MV at fields of 185 kV/cm (15-cm AK gap) using REX[1,2](a 4-MV, 5-kA,85-ns) pulsed-diode machine. The extracted current versus incident laser power, and therefore, quantum efficiency was measured for KrF at 5x10{sup -5}; ArF was significantly higher at 1x10{sup -3}. Current densities of 100 A/cm{sup 2} and total currents of 2 kA have been achieved, the latter by increasing the cathode area in proportion to the laser power.
Date: June 1996
Creator: Carlson, R. L.; Moya, S. A.; Ridlon, R. N.; Seitz, G. J. & Shurter, R. P.
Partner: UNT Libraries Government Documents Department

Recent advances in ultraviolet laser technology

Description: The science and technology of violet and ultraviolet lasers has matured rapidly in the last five years. High average power lasers have been demonstrated and several commercial product lines are now available. Single pulse devices have successfully demonstrated large output energies in well controlled beams. In this presentation we will review some of the current laser development programs in progress at Los Alamos. We will describe research in both discharge pumped lasers and E-beam pumped lasers and we will review methods of wavelength conversion in these devices. Finally we will discuss the current understanding of laser induced damage to optical components in the uv.
Date: January 1, 1985
Creator: Figueira, J.F.; Foltyn, S.R.; Rosocha, L.A.; Sze, R.C.; Tallman, C.R.; Telle, J. et al.
Partner: UNT Libraries Government Documents Department

Combination free-electron and gaseous laser

Description: A multiple laser having one or more gaseous laser stages and one or more free electron stages is described. Each of the free electron laser stages is sequentially pumped by a microwave linear accelerator. Subsequently, the electron beam is directed through a gaseous laser, in the preferred embodiment, and in an alternative embodiment, through a microwave accelerator to lower the energy level of the electron beam to pump one or more gaseous lasers. The combination laser provides high pulse repetition frequencies, on the order of 1 kHz or greater, high power capability, high efficiency, and tunability in the synchronous production of multiple beams of coherent optical radiation.
Date: June 8, 1981
Creator: Brau, C.A.; Rockwood, S.D. & Stein, W.E.
Partner: UNT Libraries Government Documents Department

Amplified spontaneous emission and pulse train amplification in a KrF amplifier

Description: We present modeling status of pulse-train amplification experiments conducted at Sandia National Laboratory in Albuquerque (SNLA) with an e-beam pumped KrF laser amplifier. The laser geometry is such that the dominant amplified spontaneous emission (ASE) growth is along the propagation axis. Our numerical studies include the propagation of on axis co- and counter-propagating fields for both the pulse train and ASE simultaneously. The time-dependent gain, absorption, formation and quenching rates are obtained from a state-of-the-art kinetics code developed at Los Alamos National Laboratory (LANL). 12 refs., 12 figs.
Date: January 1, 1988
Creator: Ackerhalt, J.R.; Hanson, D.E.; Adams, R.G.; Raymond, T.D.; Reiser, C.; Rice, J.K. et al.
Partner: UNT Libraries Government Documents Department

Optical and electrical investigations into cathode ignition and diode closure

Description: The temporal behavior of high-power diodes is closely related to the impedance collapse caused by the movement of the cathode and/or anode plasmas. This impedance collapse can be especially problematic when a constant power electron beam is required. This is the case for the very large area (square meters) diodes used to pump the amplifiers within the Aurora KrF laser system. The electron beam technology development program at Los Alamos utilizes the Electron Beam Test Facility (EGTF) to study diode physics in an attempt to better understand the basic phenomenology of ignition and closure. A combination of optical and electric diagnostics has been fielded on the Electron Beam Test Facility to study ignition and closure in large area electron beam diodes. A four-channel framing camera is used to observe the formation of microplasmas on the surface of the cathode and the subsequent movement of these plasmas toward the anode. Additionally, a perveance model is used to extract information about this plasma from voltage and current profiles. Results from the two diagnostics are compared. Closure velocity measurements are presented showing little dependence on applied magnetic field for both velvet and carbon felt emitters. We also report the first observation of the screening effect in large area cold cathode diodes. 13 refs., 11 figs.
Date: January 1, 1991
Creator: Coogan, J.J.; Rose, E.A. & Shurter, R.P.
Partner: UNT Libraries Government Documents Department

Pulsed power considerations for electron beam pumped krypton fluoride lasers for inertial confinement fusion applications

Description: The Los Alamos National Laboratory inertial confinement fusion (ICF) program is developing the krypton-fluoride excimer laser for use as an ICF driver. The KrF laser has a number of inherent characteristics that make it a promising driver candidate, such as short wavelength (0.25 {mu}m), broad bandwidth to target (>100 cm{sup {minus}1}), pulse-shaping with high dynamic range, and the potential for high overall efficiency (>5%) and repetitive operation. The large KrF laser amplifiers needed for ICF drivers are electron-beam pumped. A key issue for all laser ICF drivers is cost, and a leading cost component of a KrF laser driver is associated with the pulsed power and electron diode. Therefore, the efficient generation of electron beams is a high priority. The Los Alamos ICF program is investigating pulsed-power and diode designs and technologies to further the development of affordable KrF laser ICF drivers. 12 refs., 8 figs.
Date: January 1, 1991
Creator: Rose, E.A.; McDonald, T.E.; Rosocha, L.A.; Harris, D.B.; Sullivan, J.A. (Los Alamos National Lab., NM (USA)) & Smith, I.D. (Pulse Sciences, Inc., San Leandro, CA (USA))
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

New method for pumping an optical klystron

Description: A novel method of operation for a transverse optical klystron (TOK) is proposed. The TOK is a device in which a relativistic electron beam produces tunable coherent radiation at short wavelengths by interacting with a powerful external laser and an undulator field. Here we show that by selecting the external laser wavelengths to be one of the harmonics in the undulator radiation spectrum, excellent output at short wavelength can be realized with significantly reduced performance requirements for the undulator magnet and the storage ring providing the electron beam.
Date: January 1, 1985
Creator: Vignola, G.; Freemen, R.R.; Kincaid, B.M.; Pellegrini, C.; Luccio, A.; Murphy, J. et al.
Partner: UNT Libraries Government Documents Department

An improved hibachi support structure for electron-beam diode foils

Description: AURORA is a KrF laser system at Los Alamos designed to demonstrate the feasibility of optical multiplexing for KrF lasers. The first two amplifiers in the amplifier chain are the Small Aperture Module (SAM) and the Pre-Amplifier (PA). This paper will describe the engineering design of replacement hibachis for the SAM and PA as part of a general upgrade to increase e-beam pumping. Hibachi shading loss mechanisms are briefly discussed. A simple model that calculates relative shading losses between hibachis for the axial-field-free case is presented. Based on modeling results, sample hibachi slots were fabricated and foils tested to destruction to verify standard membrane stress equation. Test results were used in the design and fabrication of hibachis that were installed on the amplifiers. Relative energy deposition measurements using capacitive manometers are presented. 10 refs., 3 tabs.
Date: January 1, 1989
Creator: Kang, M.; Weinstein, B. & Rose, E.A.
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

Electron-beam pumped liquid excimer lasers

Description: We have investigated the excimers formed in liquid argon when various cryogenic gas mixes were excited by 1-MeV electrons. Fluorescence was detected from many excimers at their new red-shifted wavelengths, and XeO, Xe/sub 2/, and Kr/sub 2/ were lased. 25 refs., 12 figs.
Date: January 1, 1988
Creator: Loree, T.R.; Showalter, R.R.; Johnson, T.M.; Birmingham, B.S. & Hughes, W.M.
Partner: UNT Libraries Government Documents Department

Discharge excitation of the XeF C to A transition

Description: Recent success in high efficiency and high energy laser extraction of tunable radiation in the blue-green C-A transition of XeF under intense, short-pulse electron beam excitation has renewed interest in the possibility of similar performance in avalanche discharges. We present preliminary results of discharge excited fluorescence studies in a variety of devices having different degrees of energy loading.
Date: January 1, 1987
Creator: Sze, R.C.; Greene, D.P.; Bigio, I.J.; Shay, T.M.; McCown, A.W.; Figueira, J.F. et al.
Partner: UNT Libraries Government Documents Department