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in publisher: "Lawrence Livermore National Laboratory"

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Radionuclides in plankton from the South Pacific Basin

We have initiated an investigation of the utility of marine plankton as bioconcentrating samplers of low-level marine radioactivity in the southern hemisphere. A literature review has shown that both freshwater and marine plankton have trace element and radionuclide concentration factors (relative to water) of up to 10/sup 4/. We participated in Operations Deepfreeze 1981 and 1982, collecting a total of 48 plankton samples from the USCGC Glacier on its Antarctic cruises. Battelle Pacific Northw… more

Date: March 23, 1984

Creator: Marsh, K.V. & Buddemeier, R.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by {pi} radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier… more

Date: October 1, 1991

Creator: Prosnitz, D.; Scharlemann, E.T. & Sheaffer, M.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Self-referencing Mach-Zehnder interferometer as a laser system diagnostic: Active and adaptive optical systems

We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than {lambda}/10 pv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both refractive optics and catadioptric collimator to achromatize the Mach-Zehnder referen… more

Date: February 1, 1991

Creator: Feldman, M.; Mockler, D.J.; English, R.E. Jr.; Byrd, J.L. & Salmon, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Laser-plasma interaction experiments at laser wavelengths of 1. 064. mu. m, 0. 532. mu. m, and 0. 355. mu. m

The effect of laser wavelength on laser-plasma coupling is one of the critical issues facing the laser driven inertial confinement community. The advantages of using lasers with output wavelength less than 1 ..mu..m, such as enhanced absorption and hydrodynamic efficiency, reduction in parametric instabilities and corresponding suprathermal electron generation, have long been predicted theoretically.

Date: January 1, 1982

Creator: Campbell, E. M.; Mead, W. C. & Turner, R. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Institutional research and development, FY 1987

The Institutional Research and Development program at Lawrence Livermore National Laboratory fosters exploratory work to advance science and technology, disciplinary research to develop innovative solutions to problems in various scientific fields, and long-term interdisciplinary research in support of defense and energy missions. This annual report describes research funded under this program for FY87. (DWL)

Date: January 1, 1987

Creator: Struble, G. L.; Lawler, G. M.; Crawford, R. B.; Kirvel, R. D.; Peck, T. M.; Prono, J. K. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Technician support for operation and maintenance of large fusion experiments: the tandem mirror experiment upgrade (TMX-U) approach

As experiments continue to grow in size and complexity, a few technicians will no longer be able to maintain and operate the complete experiment. Specialization is becoming the norm. Subsystems are becoming very large and complex, requiring a great deal of experience and training for technicians to become qualified maintenance/operation personnel. Formal in-house and off-site programs supplement on-the-job training to fulfill the qualification criteria. This paper presents the Tandem Mirror Exp… more

Date: December 1, 1983

Creator: Mattson, G.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Use of molybdenum ion source electrodes at RTNS-II

Reports are reported for an ongoing effort to optimize D+ beam production by the MATS-III ion source used at RTNS-II. The three seven-aperture electrodes, originally consisting of water-cooled copper, have now been tested using uncooled molybdenum and with water cooling on the second (decel) electrode only. Details of the change, the results of the testing, and the benefits in operation, performance and cost are given.

Date: September 29, 1986

Creator: Massoletti, D.J.; Harter, G.A. & Heikkinen, D.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Extracted current densities from surface conversion sources of negative ions

The condition for extracting a maximum negative ion current density is found when the product of the radius of the negative ion conversion electrode, the cross-section for negative and positive ion recombination, and the density of positive ions in the ion source equals one. The optimum output is obtained at the highest positive ion density and the smallest electrode radius.

Date: February 10, 1982

Creator: Fink, J.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Cause of pitting in beryllium

Light microscopy, bare-film radiography, secondary ion mass spectroscopy, electron microprobe and physical testing were used to examine beryllium specimens exhibiting a stratified, pitted, pattern after chemical milling. The objective was to find the cause of this pattern. Specimens were found to have voids in excess of density specification allowances. These voids are attributed, at least in part, to the sublimation of beryllium fluoride during the vacuum hot pressing operation. The origin of … more

Date: April 16, 1982

Creator: Kershaw, R. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Potential for efficient frequency conversion at high average power using solid state nonlinear optical materials

High-average-power frequency conversion using solid state nonlinear materials is discussed. Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude. For example, using KD*P, efficient doubling (>70%) of Nd:YAG at average powers approaching 100 KW is possible; and for doubling to the blue or ultraviolet regions, the average power may approach 1 MW. Configurations using segmented apertur… more

Date: October 28, 1985

Creator: Eimerl, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Energy Program annual report

The national economy is particularly dependent on efficient electrical generation and transportation. Electrical demand continues to grow and will increasingly rely on coal and nuclear fuels. The nuclear power industry still has not found a solution to the problem of disposing of the waste produced by nuclear reactors. Although coal is in ample supply and the infrastructure is in place for its utilization, environmental problems and improved conversion processes remain technical challenges. In … more

Date: February 1, 1988

Creator: Borg, I.Y. (ed.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurement of energy deposited by charged-particle beams in composite targets

We have measured the energy deposited in two types of composite targets by a number of charged-particle beams: targets made of /sup 238/U, Lucite, and polyethylene were exposed to 0.26-GeV protons and 0.33-GeV deuterons, and aluminum-Lucite composites were exposed to 0.5-GeV electrons. In addition, we measured neutrons and gamma rays emitted from solid targets of various materials (including /sup 238/U and iron) exposed to 0.26-GeV protons and 0.33-GeV deuterons. We used passive detectors (ther… more

Date: July 2, 1980

Creator: Farley, E.; Becker, J.; Crase, K.; Howe, R. & Selway, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Physics of antimatter-matter reactions for interstellar propulsion

At the stage of the antiproton-nucleon annihilation chain of events relevant to propulsion the annihilation produces energetic charged pions and gamma rays. If annihilation occurs in a complex nucleus, protons, neutrons, and other nuclear fragments are also produced. The charge, number, and energy of the annihilation products are such that annihilation rocket engine concepts involving relatively low specific impulse (I/sub sp/ approx. = 1000 to 2000 s) and very high I/sub sp/ (3 x 10/sup 7/ s) … more

Date: August 22, 1986

Creator: Morgan, D.L. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Cross Sections for X-Ray Photoelectron-Induced Desorption of Hydrogen Ions From Metal Surfaces

We have measured the cross sections for x-ray photoelectron-induced desorption of hydrogen ions from beryllium, carbon, aluminum, tantalum, and gold surfaces. This report describes the results of the cross-section measurements, and discusses a time-of-flight technique that allows the determination of ionic-desorption cross sections as small as 10/sup -25/ cm/sup 2/ per photoelectron. 19 refs., 7 figs.

Date: September 20, 1985

Creator: Kinney, J. H.; Siekhaus, W. J. & Anderson, R. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Study of impurities in the Tandem Mirror Experiment using extreme-ultraviolet spectroscopy

Impurities in the Tandem Mirror Experiment (TMX) have been studied using extreme ultraviolet spectroscopy. Three time-resolving absolutely-calibrated normal-incidence monochromators, one on each section of TMX, were used to study the impurity emissions in the wavelength range of 300 A to 1600 A. The instruments on the east end cell and central cell were each capable of obtaining spatially-resolved profiles from 22 chords of the plasma simultaneously while the instrument on the west end cell mon… more

Date: May 12, 1982

Creator: Strand, O. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Recent US target-physics-related research in heavy-ion inertial fusion: simulations for tamped targets and for disk experiments in accelerator test facilities

Within the last few years, there have also appeared in the Heavy-Ion Fusion literature several studies of targets which have outer tampers. One-dimensional simulations indicate higher target gains with a judicious amount of tamping. But for these targets, a full investigation has not been carried through in regards to conservative criteria for fluid instabilities as well as reasonable imperfections in target fabrication and illumination symmetry which all affect target ignition and burn. Compar… more

Date: June 24, 1982

Creator: Mark, J.W.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Use of ICRH for startup and initial heating of the TMX-U central cell

Ion cyclotron resonance heating (ICRH) was evaluated and it was found to be satisfactory for use in establishing the conditions necessary to form a thermal barrier in TMX-upgrade (TMX-U). We discuss the constraints that must be satisfied in order to maintain a plasma, and outline a complete startup scenario that ends with the plasma at design parameters. The detailed discussions in this report concentrate on those parts of startup where ICRH is necessary. The ability of ICRH to couple power int… more

Date: May 1, 1982

Creator: Molvik, A.W. & Falabella, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

High resolution difference schemes for compressible gas dynamics

The advantages and disadvantages of four new high-resolution difference schemes, namely the von Neumann-Richtmyer, Godunovs, MUSCL and Glimms, for mathematically representing physical conditions in compressible gas flows are compared. (LCL)

Date: July 30, 1980

Creator: Woodward, P. & Colella, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Is the two-term expansion valid for highly anisotropic systems. The Townsend ionization coefficient in strong runaway as a test case

The Townsend ionization coefficient in the strong runaway regime is calculated within the framework of the two-term expansion. Results are compared to the 1-D model. General features of the two models are qualitatively similar, but quantitative differences by factors of approx. 2 are observed.

Date: July 15, 1982

Creator: Yu, S. S. & Melendez, R. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Ab initio calculations on collisions of low energy electrons with polyatomic molecules

The Kohn variational method is one of simplest, and oldest, techniques for performing scattering calculations. Nevertheless, a number of formal problems, as well as practical difficulties associated with the computation of certain required matrix elements, delayed its application to electron--molecule scattering problems for many years. This paper will describe the recent theoretical and computational developments that have made the complex'' Kohn variational method a practical tool for carryin… more

Date: August 1, 1991

Creator: Rescigno, T. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Photophoresis and the scattering of electromagnetic radiation

Electron-microscope photographs of soot lend support to the picture in which a soot particle is modeled as a collection of chains of small carbon spheres. The soot particle itself is typically considerably larger than the small carbon spheres making up the chains. Thus the soot particles might have a size approx.0.1 - 1 ..mu..m while the small carbon spheres might have a size approx.0.03 ..mu..m in typical situations. Further, measurements of the density of soot yield values much less than that… more

Date: September 1, 1985

Creator: Ipser, J.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Technology for large tandem mirror experiments

Construction of a large tandem mirror (MFTF-B) will soon begin at Lawrence Livermore National Laboratory (LLNL). Designed to reach break-even plasma conditions, the facility will significantly advance the physics and technology of magnetic-mirror-based fusion reactors. This paper describes the objectives and the design of the facility.

Date: September 4, 1980

Creator: Thomassen, K.I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Optical-scattering measurements from 1. 06-. mu. m, 0. 53-. mu. m, and 0. 35-. mu. m laser-heated disk targets

A discussion is presented on scattered light measurements relevant to three of the important parametric instabilities which occur in high intensity laser plasma interactions: stimulated Brillouin scattering (SBS), the two plasmon decay instability (2-..omega../sub pe/), and stimulated Raman scattering (SRS). Most of these experiments were carried out on the ARGUS facility. Its configuration is described for the multiple wavelength experiments, all of which were conducted with one beam illuminat… more

Date: January 1, 1982

Creator: Turner, R. E.; Campbell, E. M.; Phillion, D. W.; Mead, W. C.; Ze, F.; Max, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A cryogenic system design for the international thermonuclear experimental reactor (ITER)

A conceptual design for ITER was completed last year. The author developed a suitable cryogenic system for ITER as part of this conceptual design effort. An overview of the design is reported. Emphasis is on the fact that cryogenics is a mature science, and a system supporting ITER needs can be made from time-proven components without loss of efficiency or reliability. Because of the large size of the ITER cryogenic system, large numbers of compressors and expanders must be used. Very high reli… more

Date: September 25, 1991

Creator: Slack, D.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department