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Fusion driver study. Final technical report, April 1, 1978-March 31, 1980

Description: A conceptual design of a multi-megajoule, repetitively pulsed CO/sub 2/ laser system for Inertial Confinement Fusion is presented. System configurations consisting of 50 to 100 kJ modules operating at subatmospheric pressures with multiple pass optical extraction appear feasible with present or near term technology. Overall laser system efficiencies of greater than 10% at repetition rates in excess of 10 Hz are possible with the state-of-the-art pulsed power technology. The synthesis of all the laser subsystems into a specific configuration for a Laser Fusion Driver depends upon the reactor chamber(s) layout, subsystem reliability and restrictions on overall dimensions of the fusion driver. A design is presented which stacks power amplifier modules in series in a large torus with centrally located reactor chamber. Cost estimates of the overall Laser Fusion Driver are also presented.
Date: April 1, 1980
Creator: Friedman, H.W.
Partner: UNT Libraries Government Documents Department

Near-term feasibility demonstration of laser power beaming

Description: A mission to recharge batteries of satellites in geostationary orbits (geosats) may be a commercially viable application which could be achieved with laser systems somewhat larger than present state-of-the-art. The lifetime of batteries on geosats is limited by repetitive discharge cycles which occur when the satellites are eclipsed by the earth during the spring and fall equinoxes. By coupling high power lasers with modern, large aperture telescopes and laser guide star adaptive optics systems, present day communications satellites could be targeted. It is important that a near term demonstration of laser power beaming be accomplished using lasers in the kilowatt range so that issues associated with high average power be addressed. The Laser Guide Star Facility at LLNL has all the necessary subsystems needed for such a near term demonstration, including high power lasers for both the power beam and guide star, beam directors and satellite tracking system.
Date: January 1, 1994
Creator: Friedman, H. W.
Partner: UNT Libraries Government Documents Department

Design and performance of a laser guide star system for the Keck II telescope

Description: A laser system to generate sodium-layer guide stars has been designed, built and delivered to the Keck Observatory in Hawaii. The system uses frequency doubled YAG lasers to pump liquid dye lasers and produces 20 W of average power. The design and performance results of this laser system are presented.
Date: May 18, 1998
Creator: Friedman, H. W., LLNL
Partner: UNT Libraries Government Documents Department

Scaling of solid state lasers for satellite power beaming applications

Description: The power requirements for a satellite power beaming laser system depend upon the diameter of the beam director, the performance of the adaptive optics system, and the mission requirements. For an 8 meter beam director and overall Strehl ratio of 50%, a 30 kW laser at 850 nm can deliver an equivalent solar flux to a satellite at geostationary orbit. Advances in Diode Pumped Solid State Lasers (DPSSL) have brought these small, efficient and reliable devices to high average power and they should be considered for satellite power beaming applications. Two solid state systems are described: a diode pumped Alexandrite and diode pumped Thulium doped YAG. Both can deliver high average power at 850 nm in a single aperture.
Date: January 1, 1994
Creator: Friedman, H. W.; Albrecht, G. F. & Beach, R. J.
Partner: UNT Libraries Government Documents Department

Observing techniques for astronomical laser guide star adaptive optics

Description: We discuss astronomical observing requirements and their implementation using sodium-layer laser guide star adaptive optics. Specific issues requiring implementation include the ability to place the astronomical object at different locations within the field of view; reliable subtraction of Rayleigh-scattered light; efficient focusing; and stable point-spread-function characterization.
Date: May 1, 1998
Creator: Max, C.E.; Macintosh, B.; Olivier, S.S.; Gavel, D.T. & Friedman, H.W.
Partner: UNT Libraries Government Documents Department

Laser pulse compression in strontium and calcium vapor

Description: Application of vapor pulse compression for increasing the intensity of a large copper vapor laser pumped dye laser for x-ray generation is limited by collisional absorption and nonlinear pulse breakup. We discuss measurements of these effects. 7 refs., 1 fig., 11 tabs.
Date: November 16, 1990
Creator: Crane, J.K.; Cooke, J.D.; Shaw, M.J.; Presta, R.W.; Christensen, J.J.; Johnson, M.A. et al.
Partner: UNT Libraries Government Documents Department

Performance results on the laser portion of the Keck laser guide star system

Description: The Laser Guide Star (LGS) system for the Keck II, 10 m telescope consists of two separate but interconnected systems, the laser and the adaptive optics bench. The laser portion of the LGSl is a set of five frequency doubled YAG lasers pumping a master oscillator-power amplifier dye chain to produce up to 30 W of 589 p at 26 kHz of tuned light. Presently the laser system has been set up at the Keck facility in Waimea, HI and is undergoing test and evaluation. When it will be set up on the Keck II telescope, the pump lasers, dye master oscillator and associated control equipment will be located on the dome floor and the dye laser amplifiers, beam control system and diagnostics will be mounted directly on the telescope as shown in Fig. 1, Extensive use of fiber optics for both transmission of the oscillator pulse and the pump laser light has been used.
Date: September 29, 1998
Creator: Cooke, J B; Danforth, P M; Erbert, G V; Feldman, M; Friedman, H W; Gavel, D T et al.
Partner: UNT Libraries Government Documents Department

First significant image improvement from a sodium-layer laser guide star adaptive optics system at Lick Observatory

Description: Atmospheric turbulence severely limits the resolution of ground-based telescopes. Adaptive optics can correct for the aberrations caused by the atmosphere, but requires a bright wavefront reference source in close angular proximity to the object being imaged. Since natural reference stars of the necessary brightness are relatively rare, methods of generating artificial reference beacons have been under active investigation for more than a decade. In this paper, we report the first significant image improvement achieved using a sodium-layer laser guide star as a wavefront reference for a high- order adaptive optics system. An artificial beacon was created by resonant scattering from atomic sodium in the mesosphere, at an altitude of 95 km. Using this laser guide star, an adaptive optics system on the 3 m Shane Telescope at Lick Observatory produced a factor of 2.4 increase in peak intensity and a factor of 2 decrease in full width at half maximum of a stellar image, compared with image motion compensation alone. The Strehl ratio when using the laser guide star as the reference was 65% of that obtained with a natural guide star, and the image full widths at half maximum were identical, 0.3 arc sec, using either the laser or the natural guide star. This sodium-layer laser guide star technique holds great promise for the world`s largest telescopes. 24 refs., 4 figs., 1 tab.
Date: July 14, 1997
Creator: Olivier, S.S.; Max, C.E.; Friedman, H.W.; An, J.; Avicola, K.; Beeman, B.V. et al.
Partner: UNT Libraries Government Documents Department

Improved performance of the laser guide star adaptive optics system at Lick Observatory

Description: Results of experiments with the laser guide star adaptive optics system on the 3-meter Shane telescope at Lick Observatory have demonstrated a factor of 4 performance improvement over previous results. Stellar images recorded at a wavelength of 2 {micro}m were corrected to over 40% of the theoretical diffraction-limited peak intensity. For the previous two years, this sodium-layer laser guide star system has corrected stellar images at this wavelength to {approx}10% of the theoretical peak intensity limit. After a campaign to improve the beam quality of the laser system, and to improve calibration accuracy and stability of the adaptive optics system using new techniques for phase retrieval and phase-shifting diffraction interferometry, the system performance has been substantially increased. The next step will be to use the Lick system for astronomical science observations, and to demonstrate this level of performance with the new system being installed on the 10-meter Keck II telescope.
Date: July 20, 1999
Creator: An, J R; Avicola, K; Bauman, B J; Brase, J M; Campbell, E W; Carrano, C et al.
Partner: UNT Libraries Government Documents Department