1,531 Matching Results

Search Results

Advanced search parameters have been applied.

Hierarchical tree-structured control network for the Antares laser facility

Description: The design and implementation of a distributed, computer-based control system for the Antares 100-kJ gas laser fusion facility is presented. Control system requirements and their operational interrelationships that consider both integrated system control and individual subsystem control are described. Several configurations of minicomputers are established to provide direct control of sets of microcomputers and to provide points of operator-laser interaction. Over 100 microcomputers are located very close to the laser device control points or sources of data and perform the real-time functions of the control system, such as data and control signal multiplexing, stepping motor control, and vacuum and gas system control. These microcomputers are designed to be supported as an integral part of the control network and to be software compatible with the larger minicomputers.
Date: January 1, 1979
Creator: McGirt, F.
Partner: UNT Libraries Government Documents Department

S-20 photocathode research activity. Part I

Description: The goal of this activity has been to develop and implement S-20 photocathode processing techniques at Lawrence Livermore National Laboratory (LLNL) in order to study the physical properties of the photocathode films. The present work is the initial phase of a planned activity in understanding cathode fabrication techniques and the optical/electrical characterization of these films.
Date: November 22, 1983
Creator: Gex, F.; Huen, T. & Kalibjian, R.
Partner: UNT Libraries Government Documents Department

Evolution of shiva laser alignment systems

Description: The Shiva oscillator pulse is preamplified and divided into twenty beams. Each beam is then amplified, spatially filtered, directed, and focused onto a target a few hundred micrometers in size producing optical intensities up to 10/sup 16/W/cm/sup 2/. The laser was designed and built with three automatic alignment systems: the oscillator alignment system, which aligns each of the laser's three oscillators to a reference beamline; the chain input pointing system, which points each beam into its respective chain; and the chain output pointing, focusing and centering system which points, centers and focuses the beam onto the target. Recently the alignment of the laser's one hundred twenty spatial filter pinholes was also automated. This system uses digitized video images of back-illuminated pinholes and computer analysis to determine current positions. The offset of each current position from a desired center point is then translated into stepper motor commands and the pinhole is moved the proper distance. While motors for one pinhole are moving, the system can digitize, analyze, and send commands to other motors, allowing the system to efficiently align several pinholes in parallel.
Date: July 1, 1980
Creator: Boyd, R.D.
Partner: UNT Libraries Government Documents Department

Influence of target requirements on the production, acceleration, transport, and focusing of ion beams

Description: We have calculated the energy gain of ion-driven fusion targets as a function of input energy, ion range, and focal spot radius. For heavy-ion drivers a given target gain, together with final-lens properties, determines a 6-D phase space volume which must exceed that occupied by the ion beam. Because of Liouville's theorem and the inevitability of some phase space dilutions, the beams's 6-D volume will increase between the ion source and the target. This imposes important requirements on accelerators and on transport and focusing systems.
Date: January 1, 1981
Creator: Bangerter, R.O.; Mark, J.W.K.; Meeker, D.J. & Judd, D.L.
Partner: UNT Libraries Government Documents Department

Electrostatic levitation and transport of laser fusion targets

Description: Several levitation concepts have been evaluated resulting in the electrostatic quadrupole being chosen as the most universal. A levitator has been constructed to handle laser fusion targets during and between the processing steps. The levitator is based on a quadrupole rail which is segmented to provide electrically controlled transport and confinement along the rail. This device has demonstrated transport both vertical and horizontal of targets with appropriate mass to size ratios and exhibits remarkably stable confinement at atmospheric pressure.
Date: May 22, 1980
Creator: Johnson, W.L. & Hendricks, C.D.
Partner: UNT Libraries Government Documents Department

Filament preheating for phi targets

Description: The vaporization and preheating of a CD/sub 2/ filament inside a target is examined to investigate operation of such a target. The experimental arrangement duplicated the previous shots, with prepulse levels of 40 to 120 kV and several kA, and use of identical phi targets with CD/sub 2/ filaments. The behavior of the filament was observed by optical methods and was seen to consist of luminous and plasma phases in turn. This behavior is consistent with earlier hypotheses concerning phi target operation.
Date: February 1, 1979
Creator: Olsen, J.N.
Partner: UNT Libraries Government Documents Department

Engineering design of the Nova Laser Facility for inertial-confinement fusion

Description: The design of the Nova Laser Facility for inertial confinement fusion experiments at Lawrence Livermore National Laboratory is presented from an engineering perspective. Emphasis is placed upon design-to-performance requirements as they impact the various subsystems that comprise this complex experimental facility.
Date: January 25, 1982
Creator: Simmons, W. W.; Godwin, R. O.; Hurley, C. A.; Wallerstein, E. P.; Whitham, K.; Murray, J. E. et al.
Partner: UNT Libraries Government Documents Department

Optimization of the particle pusher in a diode simulation code

Description: The particle pusher in Sandia's particle-in-cell diode simulation code has been rewritten to reduce the required run time of a typical simulation. The resulting new version of the code has been found to run up to three times as fast as the original with comparable accuracy. The cost of this optimization was an increase in storage requirements of about 15%. The new version has also been written to run efficiently on a CRAY-1 computing system. Steps taken to affect this reduced run time are described. Various test cases are detailed.
Date: September 1, 1979
Creator: Theimer, M.M. & Quintenz, J.P.
Partner: UNT Libraries Government Documents Department

Advances in ICF power reactor design

Description: Fifteen ICF power reactor design studies published since 1980 are reviewed to illuminate the design trends they represent. There is a clear, continuing trend toward making ICF reactors inherently safer and environmentally benign. Since this trend accentuates inherent advantages of ICF reactors, we expect it to be further emphasized in the future. An emphasis on economic competitiveness appears to be a somewhat newer trend. Lower cost of electricity, smaller initial size (and capital cost), and more affordable development paths are three of the issues being addressed with new studies.
Date: April 17, 1985
Creator: Hogan, W.J. & Kulcinski, G.L.
Partner: UNT Libraries Government Documents Department

Ion beam energy deposition physics for ICF targets

Description: The target interaction physics of light ion beams will be described. The phenomenon of range shortening with increasing material temperature will be corroborated, and the concomittant phenomenon of range relengthening due to ion-electron decoupling will be introduced.
Date: January 1, 1980
Creator: Mehlhorn, T.A.
Partner: UNT Libraries Government Documents Department

Physics of laser fusion. Vol. I. Theory of the coronal plasma in laser-fusion targets

Description: This monograph deals with the physics of the coronal region in laser fusion targets. The corona consists of hot plasma which has been evaporated from the initially solid target during laser heating. It is in the corona that the laser light is absorbed by the target, and the resulting thermal energy is conducted toward cold high-density regions, where ablation occurs. The topics to be discussed are theoretical mechanisms for laser light absorption and reflection, hot-electron production, and the physics of heat conduction in laser-produced plasmas. An accompanying monograph by H. Ahlstrom (Vol.II) reviews the facilities, diagnostics, and data from recent laser fusion experiments.
Date: December 1, 1981
Creator: Max, C.E.
Partner: UNT Libraries Government Documents Department

Mechanical technology unique to laser fusion experimental systems

Description: Hardware design for laser fusion experimental machines has led to a combination of engineering technologies that are critical to the successful operation of these machines. These large opto-mechanical systems are dependent on extreme cleanliness, accommodation to efficient maintenance, and high stability. These three technologies are the primary mechanical engineering criteria for laser fusion devices.
Date: September 3, 1980
Creator: Hurley, C.A.
Partner: UNT Libraries Government Documents Department

Intense transient magnetic-field generation by laser plasma

Description: In a laser system, the return current of a laser generated plasma is conducted near a target to subject that target to the magnetic field thereof. In alternate embodiments the target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet.
Date: August 18, 1981
Creator: Benjamin, R.F.
Partner: UNT Libraries Government Documents Department

Alignment and focusing device for a multibeam laser system

Description: Large inertial confinement fusion laser systems have many beams focusing on a small target. The Antares system is a 24-beam CO/sub 2/ pulse laser. To produce uniform illumination, the 24 beams must be individually focused on (or near) the target's surface in a symmetric pattern. To assess the quality of a given beam, we will locate a Smartt (point diffraction) interferometer at the desired focal point and illuminate it with an alignment laser. The resulting fringe pattern shows defocus, lateral misalignment, and beam aberrations; all of which can be minimized by tilting and translating the focusing mirror and the preceding flat mirror. The device described in this paper will remotely translate the Smartt interferometer to any position in the target space and point it in any direction using a two-axis gimbal. The fringes produced by the interferometer are relayed out of the target vacuum shell to a vidicon by a train or prisms. We are designing four separate snap-in heads to mount on the gimbal; two of which are Smartt interferometers (for 10.6 ..mu..m and 633 nm) and two for pinholes, should we wish to put an alignment beam backwards through the system.
Date: January 1, 1980
Creator: Sweatt, W.C.
Partner: UNT Libraries Government Documents Department

Three wavelength optical alignment of the Nova laser

Description: The Nova laser, presently under construction at Lawrence Livermore National Laboratory, will be capable of delivering more than 100 kJ of focused energy to an Inertial Confinement Fusion (ICF) target. Operation at the fundamental wavelength of the laser (1.05 ..mu..m) and at the second and third harmonic will be possible. This paper will discuss the optical alignment systems and techniques being implemented to align the laser output to the target at these wavelengths prior to each target irradiation. When experiments require conversion of the laser light to wavelengths of 0.53 ..mu..m and 0.35 ..mu..m prior to target irradiation, this will be accomplished in harmonic conversion crystals located at the beam entrances to the target chamber. The harmonic alignment system will be capable of introducing colinear alignment beams of all three wavelengths into the laser chains at the final spatial filter. The alignment beam at 1.05 ..mu..m will be about three cm in diameter and intense enough to align the conversion crystals. Beams at 0.53 ..mu..m and 0.35 ..mu..m will be expanded by the spatial filter to full aperture (74 cm) and used to illuminate the target and other alignment aids at the target chamber focus. This harmonic illumination system will include viewing capability as well. A final alignment sensor will be located at the target chamber. It will view images of the chamber focal plane at all three wavelengths. In this way, each beam can be aligned at the desired wavelength to produce the focal pattern required for each target irradiation. The design of the major components in the harmonic alignment system will be described, and a typical alignment sequence for alignment to a target will be presented.
Date: November 16, 1983
Creator: Swift, C.D.; Bliss, E.S.; Jones, W.A. & Seppala, L.G.
Partner: UNT Libraries Government Documents Department

Target plane imaging system for the Nova laser

Description: The Nova laser, in operation since December 1984, is capable of irradiating targets with light at 1.05 ..mu..m, 0.53 ..mu..m, and 0.35 ..mu..m. Correct alignment of these harmonic beams uses a system called a target plane imager (TPI). It is a large microscope (four meters long, weighing one thousand kilograms) that relays images from the target chamber center to a video optics module located on the outside of the chamber. Several modes of operation are possible including: near-field viewing and far-field viewing at three magnifications and three wavelengths. In addition, the entire instrument can be scanned in X,Y,Z to examine various planes near chamber center. Performance of this system and its computer controls will be described.
Date: December 12, 1985
Creator: Swift, C.D.; Bliss, E.S.; Jones, W.A.; Reeves, R.J.; Seppala, L.G.; Shelton, R.T. et al.
Partner: UNT Libraries Government Documents Department

Inertial confinement fusion reactor systems

Description: A variety of reactor cavity concepts, drivers, and energy conversion mechanisms are being considered to realize commercial applications of ICF. Presented in this paper are: (1) a review of reactor concepts with estimates of practically achievable pulse repetition rates; (2) a survey of drivers with estimates of the requirements on reactor conditions imposed by beam propagation characteristics; and (3) an assessment of compatible driver-reactor combinations.
Date: January 1, 1980
Creator: Frank, T.G.; Bohachevsky, I.O. & Pendergrass, J.H.
Partner: UNT Libraries Government Documents Department

Shiva automatic pinhole alignment

Description: This paper describes a computer controlled closed loop alignment subsystem for Shiva, which represents the first use of video sensors for large laser alignment at LLNL. The techniques used on this now operational subsystem are serving as the basis for all closed loop alignment on Nova, the 200 terawatt successor to Shiva.
Date: September 5, 1980
Creator: Suski, G.J.
Partner: UNT Libraries Government Documents Department

Operating procedures: Fusion Experiments Analysis Facility

Description: The Fusion Experiments Analysis Facility (FEAF) is a computer facility based on a DEC VAX 11/780 computer. It became operational in late 1982. At that time two manuals were written to aid users and staff in their interactions with the facility. This manual is designed as a reference to assist the FEAF staff in carrying out their responsibilities. It is meant to supplement equipment and software manuals supplied by the vendors. Also this manual provides the FEAF staff with a set of consistent, written guidelines for the daily operation of the facility.
Date: March 20, 1984
Creator: Lerche, R.A. & Carey, R.W.
Partner: UNT Libraries Government Documents Department

Optical components for the Nova laser

Description: In addition to its other characteristics, the Nova Laser Fusion facility may well be the largest precision optical project ever undertaken. Moreover, during the course of construction, concurrent research and development has been successfully conducted, and has resulted in significant advances in various technical areas, including manufacturing efficiency. Although assembly of the first two beams of Nova is just commencing, the optical production, including construction of the special facilities required for many of the components, has been underway for over three years, and many phases of the optical manufacturing program for the first 10 beams will be completed within the next two years. On the other hand, new requirements for second and third harmonic generation have created the need to initiate new research and development. This work has been accomplished through the enormous cooperation DOE/LLNL has received from commercial industry on this project. In many cases, industry, where much of the optical component research and development and virtually all of the manufacturing is being done, has made substantial investment of its own funds in facilities, equipment, and research and development, in addition to those supplied by DOE/LLNL.
Date: May 17, 1982
Creator: Wallerstein, E.P.; Baker, P.C. & Brown, N.J.
Partner: UNT Libraries Government Documents Department

Simple scaling model for exploding pusher targets

Description: A simple model has been developed which when normalized by experiment or Lasnex calculations can be used to scale neutron yields for variations in laser input power and pulse length and target radius and wall thickness. The model also illucidates some of the physical processes occurring in this regime of laser fusion experiments. Within certain limitations on incident intensity and target geometry, the model scales with experiments and calculations to within a factor of two over six decades in neutron yield.
Date: November 4, 1977
Creator: Storm, E.K.; Larsen, J.T.; Nuckolls, J.H.; Ahlstrom, H.G. & Manes, K.R.
Partner: UNT Libraries Government Documents Department

Exploding pusher targets for the SHIVA laser system

Description: The first targets for the 20 TW SHIVA laser system were designed. They are simple glass micro-balloons, approximately 300 ..mu..m in diameter and 2 ..mu..m thick, filled with D-T gas. Using LASNEX, whose model physics was utilized successfully for ARGUS targets, we optimize for both gain and yield. The target behaves as an exploding pusher. Different simple analytic models for the physics of this mode are presented, and are tested by comparing their scaling predictions, at constant absorbed power, with those demonstrated by LASNEX. Emphasis is placed on successful prediction of the basic quantities of peak ion temperature and compression, rather than neutron yield or n tau.
Date: September 26, 1977
Creator: Rosen, M.D.; Larsen, J.T. & Nuckolls, J.H.
Partner: UNT Libraries Government Documents Department