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Report of the Working Group on Media Accelerators
A summary is given of the activities of those in the Media Accelerator Group. Attention was focused on the Inverse Cherenkov Accelerator, the Laser Focus Accelerator, and the Beat Wave Accelerator. For each of these the ultimate capability of the concept was examined as well as the next series of experiments which needs to be performed in order to advance the concept.
Date:
April 12, 1982
Creator:
Sessler, Andrew M.
System:
The UNT Digital Library
Lawrence Livermore National Laboratory laser-fusion program
The goals of the Laser-Fusion Program at Lawrence Livermore National Laboratory are to produce well-diagnosed, high-gain, laser-driven fusion explosions in the laboratory and to exploit this capability for both military applications and for civilian energy production. In the past year we have made significant progress both theoretically and experimentally in our understanding of the laser interaction with both directly coupled and radiation-driven implosion targets and their implosion dynamics. We have made significant developments in fabricating the target structures. Data from the target experiments are producing important near-term physics results. We have also continued to develop attractive reactor concepts which illustrate ICF's potential as an energy producer.
Date:
July 12, 1982
Creator:
Ahlstrom, H.G.
System:
The UNT Digital Library
Program for personnel protection from oxygen deficiency in a Fast Breeder Reactor Test Facility (FFTF)
The FFTF reactor is described. Procedures and equipment used to protect personnel from potential hazards of oxygen deficient environments are described.
Date:
December 12, 1979
Creator:
Bell, J.C.
System:
The UNT Digital Library
Target plane imaging system for the Nova laser
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.
System:
The UNT Digital Library
Novel, convenient, and nonpersistent radiotracer for environmental and energy applications
A newly-available radioisotopic system, /sup 172/Hf-/sup 172/Lu, has excellent potential for tracer applications in which nuclear data acquisition must be accomplished in real time. The 6.7-day half-life of /sup 172/Lu is sufficient for a large fraction of tracer experiments, and should allow the direct incorporation of /sup 172/Lu into tests that have traditionally utilized much longer-lived radionuclides. Since /sup 172/Lu is the daughter component of a radioisotope generator, however, its effective shelf-life is determined by the half-life of its 1.9-year /sup 172/Hf parent. Consequently, the frequency of isotope procurement need not be any more extensive than investigators would normally be accustomed to. Discussion relevant to isotope production, generator operation, and nuclide acquisition is presented in this paper.
Date:
March 12, 1984
Creator:
Grant, P.M.
System:
The UNT Digital Library
Determination of the beta energy (E/sub max/) using thin window instruments
The use of simple survey instruments for beta-energy analysis is complicated by large differences that exist in the beta spectra shapes. These spectral shapes are often complex and change continuously as the betas are absorbed in air. Changes are also caused by absorbing material between the source and the detector. One may frequently encounter a combination of beta energies, either from multiple emissions from a single isotope or from several isotopes in the sample being evaluated. There may also be monoenergetic conversion electrons present in the sample or low-energy X rays which are absorbed in a similar fashion to betas. Obviously, a complete analysis of compelx beta spectra cannot be performed using only survey instruments. We present two methods which will give the approximate E/sub max/ of the beta energy responsible for the most significant portion of the beta dose. Either technique should give adequate information about the beta spectra to provide necessary guidance for the health physics evaluation of the exposure.
Date:
August 12, 1983
Creator:
Hankins, D.E.
System:
The UNT Digital Library
Radiological design criteria for fusion power test facilities
The quest for fusion power and understanding of plasma physics has resulted in planning, design, and construction of several major fusion power test facilities, based largely on magnetic and inertial confinement concepts. We have considered radiological design aspects of the Joint European Torus (JET), Livermore Mirror and Inertial Fusion projects, and Princeton Tokamak. Our analyses on radiological design criteria cover acceptable exposure levels at the site boundary, man-rem doses for plant personnel and population at large, based upon experience gained for the fission reactors, and on considerations of cost-benefit analyses.
Date:
February 12, 1982
Creator:
Singh, M.S. & Campbell, G.W.
System:
The UNT Digital Library
Test problems in radiative transfer calculations
Several test problems are presented for evaluating the radiation diffusion equations. For spatial transport schemes, 1-D problems with known analytic solutions are tested on 2-D domains with non-orthogonal meshes. It is shown that a scheme based on the Finite Element Method is insensitive to grid distortions when the diffusion term is dominant. Other test problems deal with Compton scattering, specifically the 1-D Fokker-Planck equation coupled to an equation describing the change in electron temperature. The test problems model the evolution of a Planckian radiation field as it equilibrates with the electrons. In all cases, the numerical results are compared with the analytic ones. 15 refs., 9 figs., 7 tabs.
Date:
January 12, 1989
Creator:
Shestakov, A. I.; Kershaw, D. S. & Zimmerman, G. B.
System:
The UNT Digital Library
Nova: a high energy laser system
This review briefly describes the laser system, spatial filter, computer control system, and the 46 cm disk amplifier. (MOW)
Date:
October 12, 1979
Creator:
Godwin, R. O.
System:
The UNT Digital Library
Recent results from the PEP4-TPC on quark fragmentation
The physics goals for the PEP-4/PEP-9 experiment concentrate on two areas: the fragmentation properties of quarks and gluons produced in e+e- annihilation, and the investigation of hadron production in 2-photon collisions. Only the first of these topics is addressed. Despite the many successes of QCD in the description of deep inelastic reactions, the basic fragmentation process of quarks and gluons is not very well understood. This lack of knowledge has been shown to jeopardize precise test of QCD, such as the accurate determination of the strong coupling constant. With its ability to disentangle complex hadronic events and to identify most of the final state particles, the TPC allows new and more sensitive tests of fragmentation models. A brief description of the detector is given and particle identification by ionization energy loss is described. Next, the inclusive production of stable hadrons and of resonances is discussed, and limits on the inclusive production of fractional charged particles are given. A new analysis of long-range correlations in e+e- annihilation is given.
Date:
November 12, 1983
Creator:
Hofmann, W.
System:
The UNT Digital Library
Test and evaluation of the BBC CQK 200-4 modulator tube for the MFTF sustaining neutral beam power supply system
The BBC CQK 200-4 Tube was tested by Aydin at LLL, to confirm that it would switch 90 kV after conducting 88 amperes for 30 seconds. The CQK 200-4 is a recent modification of the CQK 200-3, an Rf transmitter tube designed for continuous loading, to increase the anode hold-off voltage to 150 kV. During the design life of the tube it will be subjected to 10/sup 5/ to 10/sup 6/ cyclic thermal loads. Two concerns are that (1) during the 30 second high current load, the screen grid may have excessive dissipation causing a loss of control of the tube, and (2) the cyclic temperature-induced stresses in the anode may cause fatigue failures that will reduce the tube's useful life. The first concern was addressed by performing full scale tests at the LLL test facility.
Date:
November 12, 1979
Creator:
Eckard, R.D.; Van Ness, H.W. & Hesselgrave, D.
System:
The UNT Digital Library
Laser driven fusion fission hybrids
The role of the fusion-fission hybrid reactor (FFHR) as a fissile fuel and/or power producer is discussed. As long range options to supply the world energy needs, hybrid-fueled thermal-burner reactors are compared to liquid metal fast breeder reactors (LMFBR). A discussion of different fuel cycles (thorium, depleted uranium, and spent fuel) is presented in order to compare the energy multiplication, the production of fissile fuel, the laser efficiency and pellet gain requirements of the hybrid reactor. LLL has collaborated with Bechtel Corporation and with Westinghouse on the conceptual design of laser fusion power plants. The neutronic studies of these two designs are discussed. The operational parameters, such as energy multiplication, power density, burn-up and plutonium production as a function of time, are also presented.
Date:
July 12, 1977
Creator:
Hansen, L. F. & Maniscalco, J. A.
System:
The UNT Digital Library
Condensed Matter at High Shock Pressures
Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N/sub 2/, CO, SiO/sub 2/-aerogel, H/sub 2/O, and C/sub 6/H/sub 6/. The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab.
Date:
July 12, 1985
Creator:
Nellis, W. J.; Holmes, N. C.; Mitchell, A. C.; Radousky, H. B. & Hamilton, D.
System:
The UNT Digital Library
Large aperture optical switching devices
We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs.
Date:
December 12, 1983
Creator:
Goldhar, J. & Henesian, M.A.
System:
The UNT Digital Library
Inertial confinement fusion (ICF). [Review of research progress]
The principal goal of the inertial confinement fusion program is the development of a practical fusion power plant in this century. Rapid progress has been made in the four major areas of ICF--targets, drivers, fusion experiments, and reactors. High gain targets have been designed. Laser, electron beam, and heavy ion accelerator drivers appear to be feasible. Record-breaking thermonuclear conditions have been experimentally achieved. Detailed diagnostics of laser implosions have confirmed predictions of the LASNEX computer program. Experimental facilities are being planned and constructed capable of igniting high gain fusion microexplosions in the mid 1980's. A low cost long lifetime reactor design has been developed.
Date:
October 12, 1977
Creator:
Nuckolls, J.
System:
The UNT Digital Library
Conservative Differencing of the Electron Fokker-Planck Transport Equation
We need to extend the applicability and improve the accuracy of kinetic electron transport codes. In this paper, special attention is given to modelling of e-e collisions, including the dominant contributions arising from anisotropy. The electric field and spatial gradient terms are also considered. I construct finite-difference analogues to the Fokker-Planck integral-differential collision operator, which conserve the particle number, momentum and energy integrals (sums) regardless of the coarseness of the velocity zoning. Such properties are usually desirable, but are especially useful, for example, when there are spatial regions and/or time intervals in which the plasma is cool, so that the collision operator acts rapidly and the velocity distribution is poorly resolved, yet it is crucial that gross conservation properties be respected in hydro-transport applications, such as in the LASNEX code. Some points are raised concerning spatial differencing and time integration.
Date:
January 12, 1981
Creator:
Langdon, A. B.
System:
The UNT Digital Library
Lip-Lip Interactions and the Growth of Multiwalled Carbon Nanotubes
Article on lip-lip interactions and the growth of multiwalled carbon nanotubes.
Date:
January 12, 1998
Creator:
Buongiorno Nardelli, Marco; Brabec, Charles; Roland, Christopher & Bernholc, Jerry
System:
The UNT Digital Library
Band Structure and Quantum Conductance of Nanostructures from Maximally Localized Wannier Functions: The Case of Functionalized Carbon Nanotubes
Article on band structure and quantum conductance of nanostructures from maximally localized Wannier functions.
Date:
August 12, 2005
Creator:
Lee, Young-Su; Buongiorno Nardelli, Marco & Marzari, Nicola
System:
The UNT Digital Library
Foreign Students Fueled 2% Rise in 1985 Graduate Science and Engineering Enrollment
Article from the National Science Foundation, noting that the 2% rise in 1985 graduate science and engineering enrollment was due to foreign students.
Date:
June 12, 1987
Creator:
National Science Foundation
System:
The UNT Digital Library
Heterodyne phase shift diagnostic for measuring atomic vapor density
We describe a technique for atomic density measurements. We generate and recombine frequency shifted laser beams producing beat signals on reference and signal detectors. Opacity in the signal detector leg is proportional to the phase difference between detector signals. 4 refs., 2 figs.
Date:
November 12, 1987
Creator:
Crane, J. K.; Paisner, J. A.; Johnson, M. A.; Story, T. W.; Barclay, C.; George, J. D. et al.
System:
The UNT Digital Library
Vacuum measurements on the Tandem Mirror Experiment Upgrade (TMX-U) fusion experiment
The gas inventory of the Tandem Mirror Experiment Upgrade (TMX-U) must be carefully controlled, if it is to successfully create various plasma configurations for thermal-barrier experiments designed to provide an improved performance for tandem-mirror experiments. This paper is a progress report on the calibration methods and pressure measurements of machine conditions deriving from recently improved neutral-beam gas control, and changes to the internal baffling geometry and the gettering system.
Date:
August 12, 1983
Creator:
Calderon, M. O.; Hunt, A. L.; Lang, D. D.; Nexsen, W. E.; Pickles, W. L. & Turner, W. C.
System:
The UNT Digital Library
MFTF supervisory control and diagnostics system hardware
The Supervisory Control and Diagnostics System (SCDS) for the Mirror Fusion Test Facility (MFTF) is a multiprocessor minicomputer system designed so that for most single-point failures, the hardware may be quickly reconfigured to provide continued operation of the experiment. The system is made up of nine Perkin-Elmer computers - a mixture of 8/32's and 7/32's. Each computer has ports on a shared memory system consisting of two independent shared memory modules. Each processor can signal other processors through hardware external to the shared memory. The system communicates with the Local Control and Instrumentation System, which consists of approximately 65 microprocessors. Each of the six system processors has facilities for communicating with a group of microprocessors; the groups consist of from four to 24 microprocessors. There are hardware switches so that if an SCDS processor communicating with a group of microprocessors fails, another SCDS processor takes over the communication.
Date:
November 12, 1979
Creator:
Butner, D.N.
System:
The UNT Digital Library
Development of a Plasma Streaming System for the Mirror Fusion Test Facility
The Plasma Streaming System (PSS) is an essential portion of the Mirror Fusion Test Facility (MFTF), scheduled for completion in October 1981. The PSS will develop a plasma density of at least 2 x 10/sup 12/ particles/cm/sup 3/ at the MFTF magnet centerline by injecting particles along the field lines. The plasma will have a midplane plasma radius as large as 40 cm with variable plasma particle energy and beam geometry. Minimum amounts of impurities will be injected, with emphasis on minimizing high Z materials. Each of the 60 PSS units will consist of a gun magnet assembly (GMA) and a power supply. Each GMA consists of a plasma streaming gun, a pulse magnet that provides variable beam shaping, and a fast reaction pulse gas valve.
Date:
November 12, 1979
Creator:
Holdsworth, T.; Clark, R.N.; McCotter, R.E.; Rossow, T.L. & Cruz, G.E.
System:
The UNT Digital Library
X-ray backlighting sources of 4 to 10 keV for laser-fusion targets
High-intensity, short-duration x-ray pulses are necessary to diagnose the compression of laser film targets. Present target designs are such that backlighting sources ranging from a few thousand electron volts to 100 keV will be necessary. The desired source durations range from a few tens of picoseconds for flash radiography to several nanoseconds for streaked backlighting, and the source occurrence must be tightly synchronized to that of the target-irradiating laser pulse. For the latter reason, a laser-induced x-ray pulse is preferred. An initial study of the K lines of Ti, Ni, and Zn as possible backlighting sources was conducted. The conversion efficiency of laser light into line radiation was obtained as a function of laser intensity, pulse length, and wavelength. A threshold laser intensity for x-ray line production was identified. Information was obtained on the size and duration of the x-ray emission source, in relation to laser parameters. The experimental results, and their impact on backlighting capability for high-density laser function targets, are discussed.
Date:
May 12, 1981
Creator:
Rupert, V. C.; Matthews, D. L. & Koppel, L. N.
System:
The UNT Digital Library