Search Results

Advanced search parameters have been applied.

TMX-Upgrade neutral-beam injection system

Description: The TMX experiment proved that axial confinement of central-cell ions is improved ninefold by the electrostatic potential of end-cell plasmas. The TMX Upgrade task is to improve this confinement further. This paper discusses the injector system aspects of the TMX Upgrade.
Date: October 5, 1981
Creator: Felker, B.; Kane, R. J.; Wong, R. L.; Calderon, M. O. & Moore, T. L.
Partner: UNT Libraries Government Documents Department

Four years of magnet system operation on the Tandem Mirror Experiment-Upgrade (TMX-U)

Description: During the past four years, the Tandem Mirror Experiment-Upgrade (TMX-U) magnet system has operated successfully, delivering more than 13,300 full-power shots. This paper presents the expanded physics criteria and how they affect the magnetic field design. It compares our operational results with previously defined criteria for current repeatability, cooling, duty cycle and vacuum integrity. It also details the solutions to a few operational problems, including the discovery and repair of a ground fault in the east plug Ioffe and another in an east plug cee circuit power supply. 14 refs.
Date: November 14, 1985
Creator: Pedrotti, L.R.; Jackson, M.C.; Bell, H.H.; Heefner, J.W. & Wong, R.L.
Partner: UNT Libraries Government Documents Department

Obtaining gigaflop performance from particle simulation of plasmas

Description: In the numerical simulation of plasma phenomena there are two fundamental approaches that are generally followed. In the continuum approach one models the evolution of the fluid moment equations derived from the appropriate Boltzmann equation of the plasma. Alternatively, in the particle approach a large group of simulated charged particles are moved according to the self-consistent electromagnetic fields which partly depend on the charge and current densities of these same particles. Although the particle simulation method has been traditionally the more expensive of the two, it is much more capable of giving adequate account of many important kinetic phenomena. With the advent of the vector multiprocessor supercomputers, such as the Cray-2 or Cray Y-MP, we have learned to adapt particle simulation codes to exploit the parallel features of these machines. Yet, in spite of such developments, the particle simulation codes have remained much slower than the maximum machine speeds. We have investigated new techniques that further optimize these methods to bring the speeds of these particle simulations into the gigaflop range. Recent progress in this area suggests that the use of particle simulation methods will become competitive with the alternative fluid models especially when it is realized that gigaflop performance makes them much more affordable. 2 refs., 3 tabs.
Date: June 1, 1990
Creator: Anderson, D.V.; Curtis, B.C.; Shumaker, D.E. (Lawrence Berkeley Lab., CA (United States)) & Horowitz, E.J. (Computer Sciences Corp., Baltimore, MD (United States))
Partner: UNT Libraries Government Documents Department

Plasma engineering for MINIMARS: a small commercial tandem mirror reactor with octopole plugs

Description: With the employment of a novel octopole end plug scheme, we examine the plasma engineering design of MINIMARS, a small compact fusion reactor based on the tandem mirror principle. With a net electric output of 600 MW/sub e/, MINIMARS is expressly designed for short construction times, factory built modules, and a passively safe blanket system. We show that the compact octopole/mantle provides several distinct improvements over the more conventional quadrupole (yin-yang) end plugs and enables ignition to be obtained with much shorter central cell length. In this way we can design economic small reactors which will minimize utility financial risk and provide attractive alternatives to the conventional larger fusion plants encountered to date.
Date: April 3, 1985
Creator: Perkins, L. J.; Logan, B. G.; Campbell, R. B. Devoto, R.S.; Blackfield, D. T. & Johnston, B. H.
Partner: UNT Libraries Government Documents Department

Fusion-neutron damage in superconductors and magnet stabilizers

Description: Two NbTi and two Cu wires were irradiated with 14.8 MeV neutrons at 4.2 K to fluences of 6 to 8 x 10/sup 20/ n/m/sup 2/, using RTNS-II. Electrical resistances of Cu were monitored during irradiation. Magnetoresistances were measured in fields up to 12.4 T before and after irradiation and after isochronal annealing up to 273 K. Critical currents of NbTi were measured after irradiation, in feilds up to 10 T. The initial rate of increase of resistivity of the Cu was found to be 2.23 x 10/sup -31/ (..cap omega..-m)/(n/m/sup 2/). This rate could be predicted from fission reactor irradiations using damage energy scaling. The maximum observed change in the NbTi critical was a decrease of 3% at 4 T. At 6, 8, and 10 T there were no significant changes.
Date: August 7, 1981
Creator: Van Konynenburg, R.A.; Guinan, M.W. & Kinney, J.H.
Partner: UNT Libraries Government Documents Department

Fragmentation of suddenly heated liquids

Description: Fragmentation of free liquids in Inertial Confinement Fusion reactors could determine the upper bound on reactor pulse rate. The x-ray ablated materials must cool and recondense to allow driver beam propagation. The increased surface area caused by fragmentation will enhance the cooling and condensation rates. Relaxation from the suddenly heated state will move a liquid into the negative pressure region under the liquid-vapor P-V dome. The lithium equation of state was used to demonstrate that neutron-induced vaporization uses only a minor fraction of the added heat, much less than would be required to drive the expansion. A 77% expansion of the lithium is required before the rapid vaporization process of spinodal decomposition could begin, and nucleation and growth are too slow to contribute to the expansion.
Date: March 1, 1985
Creator: Blink, J.A.
Partner: UNT Libraries Government Documents Department

Optical and thermal energy discharge from tritiated solid hydrogen

Description: The authors are investigating mechanisms of energy storage and release in tritiated solid hydrogens, by a variety of techniques including ESR, NMR and thermal and optical emission. The nuclear decay of a triton in solid hydrogen initiates the conversion of nuclear energy into stored chemical energy by producing unpaired hydrogen atoms which are trapped within the molecular lattice. The ability to store large quantities of atoms in this manner has been demonstrated and can serve as a basis for new forms of high energy density materials. This paper presents preliminary results of a study of the optical emission from solid hydrogen containing tritium over the visible and near infrared (NIR) spectral regions. Specifically, they have studied optical emission from DT and T{sub 2} using CCD, silicon diode and germanium diode arrays. 8 refs., 6 figs.
Date: April 2, 1991
Creator: Magnotta, F.; Mapoles, E. R.; Collins, G. W. & Souers, P. C.
Partner: UNT Libraries Government Documents Department

Verification of secure distributed systems in higher order logic: A modular approach using generic components

Description: In this paper we present a generalization of McCullough's restrictiveness model as the basis for proving security properties about distributed system designs. We mechanize this generalization and an event-based model of computer systems in the HOL (Higher Order Logic) system to prove the composability of the model and several other properties about the model. We then develop a set of generalized classes of system components and show for which families of user views they satisfied the model. Using these classes we develop a collection of general system components that are instantiations of one of these classes and show that the instantiations also satisfied the security property. We then conclude with a sample distributed secure system, based on the Rushby and Randell distributed system design and designed using our collection of components, and show how our mechanized verification system can be used to verify such designs. 16 refs., 20 figs.
Date: January 1, 1991
Creator: Alves-Foss, J. & Levitt, K.
Partner: UNT Libraries Government Documents Department

Immobilization of high level nuclear reactor wastes in SYNROC: a current appraisal. [Synthetic perovskite and hollandite; natural zirconolite and perovskite]

Description: Results are presented for leach testing at 95/sup 0/C and 200/sup 0/C of SYNROC containing 9% and 20% simulated high level radioactive waste, synthetic hollandite and pervoskite samples, and natural zirconolite and pervoskite samples. Single phase synthetic minerals show much higher leach rates than natural mineral samples and polyphase SYNROC samples. Natural zirconolite samples with low radiation damage have leach rates at 200/sup 0/C based on U which are identical to those measured on SYNROC samples. Natural zirconolites with very large accumulated ..cap alpha.. dose and radiation damage have leach rates at 200/sup 0/C which are only 5 times higher than those of low dose samples.
Date: October 13, 1981
Creator: Oversby, V.M. & Ringwood, A.E.
Partner: UNT Libraries Government Documents Department

Mechanical considerations for MFTF-B plasma-diagnostic system

Description: The reconfiguration of MFTF to a tandem mirror machine with thermal barriers has caused a significant expansion in the physical scope of plasma diagnostics. From a mechanical perspective, it complicates the plasma access, system interfaces, growth and environmental considerations. Conceptual designs characterize the general scope of the design and fabrication which remains to be done.
Date: October 19, 1981
Creator: Thomas, S.R. Jr. & Wells, C.W.
Partner: UNT Libraries Government Documents Department

Heavy-ion inertial fusion: initial survey of target gain versus ion-beam parameters

Description: Inertial-fusion targets have been designed for use with heavy-ion accelerators as drivers in fusion energy power plants. We have made an initial survey of target gain versus beam energy, power, focal radius, and ion range. This provides input for understanding the trade-offs among accelerator designs.
Date: October 26, 1981
Creator: Bangerter, R.O.; Mark, J.W.K. & Thiessen, A.R.
Partner: UNT Libraries Government Documents Department

Microwave kinoform for magnetic fusion

Description: A microwave kinoform that modifies both the phase and polarization of an incident wavefront has been designed. This kinoform for the TMX-U magnetic fusion experiment has been fabricated and tested. The design procedure, method of fabrication, and experimental test results are discussed.
Date: July 19, 1983
Creator: Gallagher, N.C. Jr. & Sweeney, D.W.
Partner: UNT Libraries Government Documents Department

Visual simulation of radiographs

Description: A method for computer simulation of radiographs has been added to the LLNL version of the solid modeler TIPS-1 (Technical Information Processing System-1). This new tool will enable an engineer to compare an actual radiograph of a solid to its computer-generated counterpart. The appearance of discrepancies between the two can be an indication of flaws in the solid object. Simulated radiographs can also be used to preview the placement of x-ray sources to focus on areas of concern before actual radiographs are made.
Date: January 18, 1985
Creator: Laguna, G.
Partner: UNT Libraries Government Documents Department

Wavelength dependence and efficiency of laser heating of DT-filled polymer-coated glass microspheres at cryogenic temperatures

Description: We have determined experimentally the fraction of laser light incident on DT filled cryogenic polymer coated and bare glass microsphere targets that is absorbed to produce target heating. Data have been obtained for bare glass and CH and CF polymer coated microspheres at 488 nm and 632 nm laser wavelengths. The measurement technique used and experimental results obtained are presented.
Date: September 24, 1981
Creator: Darling, D.H.; Bernat, T.P. & Ives, B.H.
Partner: UNT Libraries Government Documents Department

Normal zone detectors for a large number of inductively coupled coils

Description: In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this paper uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages. The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take place in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent.
Date: November 28, 1983
Creator: Owen, E.W. & Shimer, D.W.
Partner: UNT Libraries Government Documents Department

Pre-equilibrium decay processes in energetic heavy ion reactions

Description: The Boltzmann master equation (BME) is defined for application to precompound decay in heavy ion reactions in the 10 100 MeV/nucleon regime. Predicted neutron spectra are compared with measured results for central collisions of /sup 20/Ne and /sup 12/C with /sup 165/Ho target nuclei. Comparisons are made with subthreshold ..pi../sup 0/ yields in heavy ion reactions between 35 and 84 MeV/nucleon, and with the ..pi../sup 0/ spectra. The BME is found to be an excellent tool for investigating these experimentally observed aspects of non-equilibrium heavy ion reactions. 18 refs., 8 figs.
Date: April 15, 1986
Creator: Blann, M.
Partner: UNT Libraries Government Documents Department

Flibe/Be/He/FS concept (R = 1)

Description: The blanket concept is described. Beryllium, in the form of pebbles nominally 1 cm diameter in a 20 cm thick bed, is employed to multiply neutrons. The multiplier zone is followed by a zone of silicon carbide (SiC) which slows neutrons. Neutrons are captured in the Lithium-6 carried in the molten fluoride salt (LiF + BeF- melting point, 363/sup 0/C) to breed tritium and release extra energy in exothermic nuclear rections. The salt flows slowly through tubes in the blanket and out to a simple flash separator where the tritium is removed. Helium flows radially through the Be pebble bed and SiC region carrying the heat out to the thermal conversion plant. The tubes are coated either on the inside or outside with a 10 ..mu..m tungsten barrier by chemical vapor deposition to cut down tritium permeation to the helium coolant circuit. With the tungsten barrier on the inside the tritium inventory in the tube walls is small and tungsten will contribute to corrosion inhibition. A 1-mm aluminum jacket on the steam generator tubes keeps the tritium permeation to the steam down to 30 curies per day. The design can be converted into a fission-suppressed fissile breeder by thickening the beryllium zone by a factor of 2 or so and adding ThF/sub 4/ to the salt in which case 6 tonnes of uranium-233 would be produced per year.
Date: October 1, 1984
Creator: Moir, R.
Partner: UNT Libraries Government Documents Department

Burro-series gas-concentration contours

Description: Gas concentration contours generated from the data taken during the Burro series experiments 8 and 9 are presented. The contours are presented as a function of time in both a horizontal and a vertical format for several areas within the array.
Date: December 23, 1981
Creator: Koopman, R.P.
Partner: UNT Libraries Government Documents Department

Wide spectrum microwave pulse measurement

Description: Various techniques are postulated as diagnostics for wide band microwave pulses. The diagnostics include determinations of both the instantaneous amplitude and the frequency content of one-shot pulses. 6 refs., 11 figs. (WRF)
Date: January 1, 1986
Creator: King, R.J.
Partner: UNT Libraries Government Documents Department

Investigation of particle-laden turbulent flow in free shear turbulent combustion

Description: Explicit numerical mixed phase simulations are described which couple random gasdynamic motions to inertiallly interactive gas borne particles. Theses simulations are numerical experiments intended to provide data for investigating the interaction between a developing turbulent free shear layer and gas borne solid particles it entrains. The simulations predict most probable distributions of dispersed phase trajectories, standard deviations, and gas phase mixing dynamics which include the concomitant back-influences of the particle phase on the carrier gas flow. Data for refinement of the computational scheme and physical verification are provided by experiment. The experimental evidence is developed in a splitter plate divided, two-channel free shear mixing combustion tube. A variety of particle concentrations and particle size distributions are admitted into non-combusting or combusting flows with selected heat release levels. The computations, in turn, provide guidance on design and selection of new experiments.
Date: January 1, 1983
Creator: Buckingham, A.C.; Siekhaus, W.J.; Ellzey, J. & Daily, J.W.
Partner: UNT Libraries Government Documents Department

Modeling and optimization of operating parameters for a test-cell option of the Fusion Power Demonstration-II tandem mirror design

Description: Models of tandem mirror devices operated with a test-cell insert have been used to calculate operating parameters for FPD-II+T, an upgrade of the Fusion Power Demonstration-II device. Two test-cell configurations were considered, one accommodating two 1.5 m blanket test modules and the other having four. To minimize the cost of the upgrade, FPD-II+T utilizes the same coil arrangement and machine dimensions outside of the test cell as FPD-II, and the requirements on the end cell systems have been held near or below those for FPD-II. The maximum achievable test cell wall loading found for the short test-cell was 3.5 MW/m/sup 2/ while 6.0 MW/m/sup 2/ was obtainable in the long test-cell configuration. The most severe limitation on the achievable wall loading is the upper limit on test-cell beta set by MHD stability calculations. Modification of the shape of the magnetic field in the test-cell by improving the magnet design could raise this beta limit and lead to improved test-cell performance.
Date: April 3, 1985
Creator: Haney, S.W. & Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

The Hazardous Material Technician Apprenticeship Program at Lawrence Livermore National Laboratory

Description: This document describes an apprenticeship training program for hazardous material technician. This entry-level category is achieved after approximately 216 hours of classroom and on-the-job training. Procedures for evaluating performance include in-class testing, use of on-the-job checks, and the assignment of an apprentice mentor for each trainee. (TEM)
Date: July 1, 1987
Creator: Steiner, S.D.
Partner: UNT Libraries Government Documents Department

RTNS-II fusion-neutron facility for material-damage studies

Description: The Rotating Target Neutron Source-II (RTNS-II) is operated by Lawrence Livermore National Laboratory (LLNL) for the US (DOE) and Japan (Monbusho). Joint support and utilization of the facility by Japan and the US has been in effect for nearly 1 1/2 years. Irradiations, using the fusion neutrons produced at RTNS-II, are done in support of the fusion energy programs of the US and Japan. In addition, add-on non-fusion related irradiations can and have been done at RTNS-II.
Date: June 1, 1983
Creator: Heikkinen, D.W. & Logan, C.M.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen