150 Matching Results

Search Results

Results: 1 - 24 next
open access

Light Absorption and Scattering Mechanisms in Laser Fusion Plasmas

Description: The picture of laser light absorption and scattering which is emerging from theory and computer simulation studies of laser-plasma interactions is described. On the subject of absorption, we discuss theoretical and experimental evidence that resonance absorption in a steepened density profile is a dominant absorption mechanism. Recent work also indicates the presence of critical surface ripples, which we study using two and three dimensional computer simulations. Predictions of hot electron spe… more
Date: October 4, 1977
Creator: Barnes, C.; Estabrook, K. G.; Kruer, W. L.; Langdon, A. B.; Lasinski, B. F.; Max, C. E. et al.
Partner: UNT Libraries Government Documents Department
open access

High-energy proton radiation damage of high-purity germanium detectors

Description: Motivated by their applicability to gamma-ray spectroscopy experiments in space, quantitative studies of radiation damage effects in high-purity germanium detectors due to high-energy charged particles have been initiated with the irradiation by 6 GeV/c protons of two 1.0 cm thick planar detectors maintained at 88/sup 0/K. The threshold for resolution degradation and the annealing characteristics differs markedly from those previously observed for detectors irradiated by fast neutrons. Under pr… more
Date: October 1, 1977
Creator: Pehl, R.H.; Varnell, L.S. & Metzger, A.E.
Partner: UNT Libraries Government Documents Department
open access

Calorimetric and optical beam diagnostics on the LBL 120-keV neutral beam test facility

Description: The 120-keV Neutral Beam Test Facility at LBL is fitted with several types of instrumentation to determine the properties of the 10- to 15-A hydrogen and deuterium beams produced in this facility. These include a neutral particle dump for measuring the temperature profile generated by the beam, and a fixed and a moveable ion dump to measure the temperature profiles generated by the various ion components after they have been swept out of the neutral beam by a bending magnet. These several dumps… more
Date: October 1, 1977
Creator: Burrell, C. F.; Cooper, W. S.; Steele, W. F. & Smith, R. R.
Partner: UNT Libraries Government Documents Department
open access

New generation of arc and arc filament power supplies for pulsed neutral beams

Description: The new Tandem Mirror Experiment (TMX) facility at LLL requires that neutral beams operate for pulse lengths between 25 and 100 ms. The inevitable increase in cost over the present 12-ms pulse length capability dictated that a more economical alternative to the pulse forming networks and the transformer-type arc filament power supplies currently in use be found. A study of the various alternatives and design requirements revealed that battery banks are the most economical alternative. The therm… more
Date: October 3, 1977
Creator: Santamaria, G.T.
Partner: UNT Libraries Government Documents Department
open access

High resolution x-ray crystal spectrographs

Description: Observation of x-ray line emissions are valuable for determining the thermodynamic state of the emitting plasma. For laser produced plasmas, diffraction crystals can be used to isolate x-ray monochromes to obtain high resolution spectral measurements. We will describe a versatile multi-crystal high resolution spectrograph used for photon energies from 0.5 to 6 keV. We will discuss a calculational package that tunes the response and sensitivity of the instrument and estimates the effect of sourc… more
Date: October 21, 1977
Creator: Koppel, L. N. & Eckels, J. D.
Partner: UNT Libraries Government Documents Department
open access

Applications of concrete polymer materials for the rehabilitation of bridge decks

Description: The rapid deterioration of concrete bridge decks as a result of the increased use of deicing salts is one of the most severe problems facing the highway industry today. One possible solution to the problem is the use of concrete polymer materials. The materials of prime interest are polymer-impregnated concrete (PIC) and polymer concrete (PC), both of which have excellent durability and strength properties. Three potential applications: repair of deteriorated bridge decks, polymer impregnation … more
Date: October 1, 1977
Creator: Kukacka, L. E.
Partner: UNT Libraries Government Documents Department
open access

Profile modification by the ponderomotive force in spherical targets

Description: Experiments have been performed by LLL which indicate a definite density profile steepening. One possible mechanism for this effect is the ponderomotive force. LASNEX has been modified to include the light momentum deposition in the form rho dv/dt = -nabla P - nabla(radical epsilon + radical 1/epsilon) I/2c. Results will be presented from numerical simulations on spherical glass targets at laser intensities from 10/sup 14/ to 10/sup 16/ watts/cm/sup 2/. Emphasis is placed on the nature of the d… more
Date: October 26, 1977
Creator: Larsen, J. T. & Harte, J.
Partner: UNT Libraries Government Documents Department
open access

Data telecommunications at the CSCF

Description: At Brookhaven National Laboratory data telecommunication for remote job entry, interactive time sharing, networking, graphics, and special purpose links became increasingly important--they now rival the more traditional over-the-counter traffic. The BNL Central Scientific Computing Facility (CSCF) responded to this need with a number of developments. The latest and most comprehensive of these is a ''front-end'' communications system built around MODCOMP II computers. To put this project into it… more
Date: October 1, 1977
Creator: Peskin, A. M.
Partner: UNT Libraries Government Documents Department
open access

Lead-Glass Wall addition to the Spear Mark I Magnetic Detector

Description: A ''Lead-Glass Wall,'' consisting of 318 lead-glass Cherenkov shower counters and three wire spark chambers, has been added to one octant of the SPEAR Mark I Magnetic Detector. The wall covers a solid angle of approximately 6 percent of 4..pi.. steradians and has been used to identify and measure the energies of electrons and photons produced in electron-positron collisions. The design, calibration, gain-monitoring, and performance of the system are described.
Date: October 1, 1977
Creator: Feller, J. M.; Barbaro-Galtieri, A. & Dorfan, J. M.
Partner: UNT Libraries Government Documents Department
open access

Notes on Luminosity Variation at ISABELLE

Description: In the present ISABELLE design, the luminosity at each insertion will be the same, unless special efforts are taken to get a low-..beta.. insertion or reduced crossing angle. These can only change the luminosity by factors of 2 to 4 from insertion to insertion. An estimation of the range of desired luminosities is given.
Date: October 19, 1977
Creator: Herrera, J. C.; Marx, M.; Roe, B. & Rosenberg, E. I.
Partner: UNT Libraries Government Documents Department
open access

Time resolution performance studies of contemporary high speed photomultipliers

Description: The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850… more
Date: October 5, 1977
Creator: Leskovar, B. & Lo, C.C.
Partner: UNT Libraries Government Documents Department
open access

Performance of the short-pulse oscillators for Argus and Shiva

Description: The large Nd:glass laser-fusion systems, such as Argus and Shiva, require short-pulse oscillators that are very reliable and predictable. The requirements go well beyond what can reasonably be expected from a passively mode-locked laser. An actively mode-locked and Q-switched oscillator has now been developed that is extremely reliable and predictable, and satisfies all the requirements for the present Nd:glass laser systems. These systems require pulses that are adjustable from less than 100 p… more
Date: October 1, 1977
Creator: Kuizenga, D.J. & Martin, W.E.
Partner: UNT Libraries Government Documents Department
open access

Design studies of a laser fusion power plant

Description: The conceptual design of a laser fusion power plant has been undertaken to exploit recent developments in target design. Advanced high-gain targets which have been developed make it possible to significantly relax the laser and optical system requirements. The power plant design features a reactor concept which utilizes a thick falling region of liquid lithium to protect the first-wall from the neutrons, x-rays, and charged particles that are produced in the thermonuclear microexplosion. The li… more
Date: October 7, 1977
Creator: Maniscalco, J. A.; Meier, W. R. & Monsler, M. J.
Partner: UNT Libraries Government Documents Department
open access

Requirements and new materials for fusion laser systems

Description: Higher focusable power in neodymium glass fusion lasers can be obtained through the use of new materials with lower nonlinear index (n/sub 2/) and better energy storage capabilities than the presently employed silicate glass. Silicate, phosphate, fluorophosphate, and beryllium fluoride glasses are discussed in terms of fusion laser requirements, particularly those for the proposed Nova laser. Examples of the variation in spectroscopic and optical properties obtainable with compositional changes… more
Date: October 1, 1977
Creator: Stokowski, S. E.; Weber, M. J.; Saroyan, R. A. & Hagen, W. F.
Partner: UNT Libraries Government Documents Department
open access

New method to determine the chemical composition and structure of non-elemental acceptor and donor centers in ultra-pure germanium

Description: A new approach towards the understanding of hitherto unknown, non-elemental acceptors and donors which can limit the purity of ultra-pure germanium has been explored for a specific pair of shallow centers, designated A/sub 2/ and D. Using photoelectric spectroscopy, we have demonstrated that an isotope shift in the ground-state binding energy occurs when the germanium crystals are grown in pure deuterium instead of in the usual pure hydrogen atmosphere. This isotope shift is the most direct pro… more
Date: October 1, 1977
Creator: Haller, E.E.
Partner: UNT Libraries Government Documents Department
open access

Energy balance measurements for Shiva

Description: The Lawrence Livermore Laboratory Shiva laser-target interaction facility is designed for experiments at 20 to 30 terawatts. At this power level there will be larger fluxes of neutrons, x-rays, electrons and ions than have been previously measured. The measurements of energy converted into the various reaction products is crucial both in target design and performance analysis of the actual experiment. The total energy absorbed is measured by a box calorimeter surrounding the target except for b… more
Date: October 24, 1977
Creator: Glaros, S.S.; Rupert, V.C.; Gunn, S.R.; Phillion, D.W. & Kornblum, H.N.
Partner: UNT Libraries Government Documents Department
open access

Electrostatically driven plasma hydrodynamic instability. I. The failure of vacuum-insulated, long wavelength laser fusion pellets

Description: Longer wavelength (e.g., lambda = 10.5 ..mu..m) laser radiation generates relatively large fluxes of superthermal electrons that penetrate and preheat the cores of such pellets at early times in their implosion history, precluding their efficient subsequent compression. It has been proposed to separate the outermost shell of such pellets (onto which the laser light is directed) from its inner regions by a vacuum layer, thereby ''insulating'' these inner portions from superthermal electron degra… more
Date: October 1, 1977
Creator: Levermore, C. D.; Caflisch, R. E. & Wood, L. L.
Partner: UNT Libraries Government Documents Department
open access

Interactive display of polygonal data

Description: Interactive computer graphics is an excellent approach to many types of applications. It is an exciting method of doing geographic analysis when desiring to rapidly examine existing geographically related data or to display specially prepared data and base maps for publication. One such program is the interactive thematic mapping system called CARTE, which combines polygonal base maps with statistical data to produce shaded maps using a variety of shading symbolisms on a variety of output devic… more
Date: October 1, 1977
Creator: Wood, P.M.
Partner: UNT Libraries Government Documents Department
open access

Tokamak Fusion Test Reactor neutral beam injection system vacuum chamber

Description: Most of the components of the Neutral Beam Lines of the Tokamak Fusion Test Reactor (TFTR) will be enclosed in a 50 cubic meter box-shaped vacuum chamber. The chamber will have a number of unorthodox features to accomodate both neutral beam and TFTR requirements. The design constraints, and the resulting chamber design, are presented.
Date: October 19, 1977
Creator: Pedrotti, L.R.
Partner: UNT Libraries Government Documents Department
open access

Modeling subsidence due to geothermal fluid production

Description: Currently, liquid dominated geothermal systems hold the maximum promise for exploiting geothermal energy in the United States. The principal characteristic of such systems is that most of the heat is transferred by flowing water, which also controls subsurface fluid pressures and stress changes. The reduction in pore pressures brought about by geothermal fluid extraction is potentially capable of causing appreciable deformation of the reservoir rocks leading to displacements at the land surface… more
Date: October 1, 1977
Creator: Lippmann, M.J.; Narasimhan, T.N. & Witherspoon, P.A.
Partner: UNT Libraries Government Documents Department
open access

Fast optical shutters for Nova, a high power fusion laser

Description: Preliminary design and performance test results for fast optical shutters intended for use in the Nova high power fusion laser system are briefly described. Both an opening shutter to protect the pellet target from amplified spontaneous emission (ASE), and a closing shutter to protect the laser from light reflected back from the target are discussed. Faraday rotators, synchronized by a 400 Hz oscillator, provide an opening shutter mechanism with an opening time of approximately 10 ..mu..s. A pl… more
Date: October 18, 1977
Creator: Bradley, L. P.; Gagnon, W. L. & Carder, B. M.
Partner: UNT Libraries Government Documents Department
open access

Antisymmetrization effects in heavy-ion potentials and their dependence on the nucleon--nucleon interaction

Description: Double-folding heavy-ion potentials are conventionally generated by folding the densities of projectile and target with a nucleon--nucleon interaction. The success of the folding method has recently been explained by Fleckner and Mosel (Nucl. Phys. A277, 170 (1977)) in terms of a cancellation effect between two types of approximations, namely, the effects of neglecting the antisymmetrization between the ions and the polarization of the densities due to the (Coulomb and nuclear) forces between t… more
Date: October 1, 1977
Creator: Schultheis, H. & Schultheis, R.
Partner: UNT Libraries Government Documents Department
open access

SCR series switch and impulse crowbar at the Lawrence Berkeley Laboratory for CTR neutral beam source development

Description: The series switch is designed to operate at 120kV and pass 65A for 0.5 sec every 30 sec on the Lawrence Berkeley Laboratory CTR Neutral Beam Source Test Stand IIIB. The series switch consists of 400 individual SCR circuits connected in series and is turned on by a simple system of cascaded pulse transformers with multiple single turn secondaries each driving the individual SCR gates. It is turned off by an SCR impulse crowbar that momentarily shorts the power supply allowing the series switch t… more
Date: October 1, 1977
Creator: Franck, J. V.; Arthur, A. A.; Brusse, L. A. & Low, W.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen