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in subjects: "Absorption"

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Light Absorption and Scattering Mechanisms in Laser Fusion Plasmas

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Successive collision calculation of resonance absorption

The successive collision method for calculating resonance absorption solves numerically the neutron slowing down problem in reactor lattices. A discrete energy mesh is used with cross sections taken from a Monte Carlo library. The major physical approximations used are isotropic scattering in both the laboratory and center-of-mass systems. This procedure is intended for day-to-day analysis calculations and has been incorporated into the current version of MUFT. The calculational model used for … more

Date: July 1, 1980

Creator: Schmidt, E. & Eisenhart, L.D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Laser diagnostics of H sup minus formation in a magnetic multicusp ion source

The populations of ground electronic state atomic hydrogen and ground electronic state, vibrationally-rotationally excited hydrogen molecules in a negative hydrogen ion source discharge have been measured using vacuum ultraviolet (VUV) laser absorption spectroscopy. Vibrational states up to v=8 and rotational levels as high as J=15 have been measured. The measurements have been made under a range of discharge conditions. The complete vibrational population distribution for v=1-8, J=1 has been o… more

Date: May 1, 1991

Creator: Young, A. T.; Chen, P.; Kunkel, W. B.; Leung, K. N.; Li, C. Y. & Stutzin, G. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Atomic structure of clusters through chemical reactions

Techniques for the probing of isolated metal cluster structure through adsorbate binding patterns will be described. The saturation of clusters with reagents such as ammonia and nitrogen provides information on the number of preferred binding sites for these reagents. The dependence of this number on cluster size can suggest particular structural themes. The equilibrium reaction with water can be used to identify cluster sizes having especially enhanced binding for the water molecule. Again, th… more

Date: January 1, 1991

Creator: Riley, S.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Numerical simulations of turbulent flow fields caused by spraying of water on large releases of hydrogen fluoride

The effectiveness of water sprays in absorbing HF releases was recently demonstrated in extended laboratory and field tests. In this paper, computer simulations are presented of the Hawk, Nevada Test Site, series of field tests. The model used, HFSPRAY, is a Eulerean/Lagrangian model which simulates the momentum, mass and energy interactions between a water spray and a turbulent plume of HF in air; the model can predict the flow velocities, temperature, water vapor, and HF concentration fields … more

Date: May 1, 1991

Creator: Fthenakis, V.M. (Brookhaven National Lab., Upton, NY (United States)) & Schatz, K.W. (Mobil Research and Development Corp., Princeton, NJ (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Multigroup formalism for evaluation of continuous slowing down theory parameters

Continuous slowing down theory calculations have been found to yield significant discrepancies in the presence of strong absorption. An algorithm has been formulated for evaluating continuous slowing down theory parameters which should be applicable for cases with strong absorption. Excellent agreement with more precise calculations is obtained when the new parameters are used.

Date: January 1, 1975

Creator: Parvez, A. & Becker, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Enhanced lower hybrid penetration via intense multi-microsecond pulses

Applying lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present theoretical description of the absorption which accounts for transient collisional effects as well as nonlinear broadening of the resonant plateau. We show results from ray-tracing calculations which include the nonlinear absorption. We also derive the conditions required for pump depletion by parametric instabilities, and assess density deple… more

Date: January 1, 1991

Creator: Cohen, R. H.; Rognlien, T. D. (Lawrence Livermore National Lab., CA (United States)); Bonoli, P. T. & Porkolab, M. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Dosimetry measurements external to a 10 kiloliter liquid-air vessel containing a D-T neutron source. [14 MeV neutrons]

To determine the radiation attenuation characteristics of liquid air (109 g/cm/sup 2/ thick) for 14 MeV neutrons from a central D-T source in a 10 kL vessel, radiation dose measurements were made using a large tissue-equivalent ion chamber external to the vessel. The shielding characteristics of steel spherical shells were also investigated. Experimental results were analyzed and compared with TARTNP Monte Carlo code calculations. Degradation of the ion chamber's response to high-energy neutron… more

Date: October 10, 1977

Creator: Tripler, D. J.; Goldberg, E. & Farley, W. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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ECH propagation and absorption experiments at 140 GHz in MTX

Single pass absorption experiments using fundamental, O-mode ECH waves have been performed in the Microwave Tokamak Experiment (MTX) and found to be consistent with linear absorption theory, as predicted for the ECH source which is a 140 GHz, 400 kW CW gyrotron. These experiments provide the basis for comparison with future Free Electron Laser (FEL) experiments in which the absorption is predicted to be in the non-linear regime for P{sub FEL} {ge} 1 GW. The gyrotron power is coupled into a quas… more

Date: August 1, 1991

Creator: Fenstermacher, M. E.; Allen, S. L.; Casper, T. A.; Foote, J. H.; Hooper, E. B.; Johnston, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Assessment and development of an advanced heat pump for recovery of volatile organic compounds

This report documents Phase 1 of a project conducted by Mechanical Technology Incorporated (MTI) for the assessment and development of an advanced heat pump for recovery of VOC solvents from process gas streams. In Phase 1, MTI has evaluated solvent recovery applications within New York State (NYS), identified host sites willing to implement their application, and conducted a preliminary design of the equipment required. The design and applications were evaluated for technical and economic feas… more

Date: June 1, 1992

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Considerations for the use of synchrotron radiation sources to measure sub-keV x-ray photoabsorption cross sections in transmission

Sub-keV x-ray photoabsorption cross section measurements in transmission have been made using synchrotron radiation beam lines on the VUV storage ring at the National Synchrotron Light Source (NSLS) and on the SPEAR storage ring at Stanford. The experimental considerations associated with making absolute measurements are reviewed, along with techniques for resolving difficulties. Suggestions for future measurements are included.

Date: February 1, 1988

Creator: Tirsell, K.G. & Del Grande, N.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Direct electron heating by 60 MHz fast waves on DIII-D

Efficient direct electron heating by fast waves has been observed on the DIII-D tokamak. A four strap antenna with (0,{pi},0,{pi}) phasing launched up to 1.6 MW of fast wave power with {vert bar}n{sub {parallel}}{vert bar} {approx} 11. This {vert bar}n{sub {parallel}}{vert bar} is suitable for strong electron interaction in ohmic target plasmas (T{sub e} {le} 2 keV). Ion cyclotron absorption was minimized by keeping the hydrogen fraction low ({lt}3%) in deuterium discharges and by operating at … more

Date: October 1, 1991

Creator: Petty, C. C.; Pinsker, R. I.; Mayberry, M. J.; Chiu, S. C.; Luce, T. C.; Prater, R. (General Atomics, San Diego, CA (United States)) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental test of resonant absorption theory. Final report, January 1, 1978-December 31, 1979

This experimental research has probed the nature of resonant absorption (RA) of laser light by laser-produced plasmas. The plasmas were created by optical breakdown of a shockfront produced in an electrothermal shock tube. This procedure allows the density structure of the plasma, and in particular, the orientation of the plasma critical-density surface, to be reproducibly formed from one shot to the next. Thus, for the first time, RA has been controllably and reproducibly studied in isolation … more

Date: May 1, 1979

Creator: Yablonovitch, E

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A program to obtain reliable photoabsorption cross sections

A program to obtain reliable photoabsorption cross sections for a broad range of elements has been initiated at Lawrence Livermore National Laboratory. Using well-characterized samples, absolute measurements have been made with overall uncertainties of /+-/10% or less over energy ranges from about 50 eV to several keV, at several synchrotron radiation facilities. More than a dozen elements have been investigated and other measurements are being planned for elements beryllium (Z-4) through urani… more

Date: January 1, 1988

Creator: Del Grande, N.K. & Tirsell, K.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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PICLE: a 2-D code for laser-beam - gas-jet interaction studies

A heat transport hydrodynamic PIC code was adapted for application to the KMSF gas-jet experiments. The input material density profile was changed from the original solid slab geometry to a cylindrically symmetric profile modeling the gas-jet plume. The target material was changed from the original Z = 1 to arbitrary Z. Energy deposition was modified to include inverse bremsstrahlung and resonance absorption. Preliminary results indicate electron thermal conduction dominates over mass flow for … more

Date: January 1, 1981

Creator: Dunning, M.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Direct electron absorption of fast waves on the D3-D tokamak

No Description Available.

Date: June 1, 1992

Creator: Petty, C. C.; Pinsker, R. I.; Chiu, S. C.; deGrassie, J. S.; Lohr, J.; Luce, T. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sensitivity study of neutron transport through standard and rebar concrete

An investigation is under way at ORNL to (1) develop a data base pertinent to the transport of neutrons through thick concrete shields, (2) use the data base in an energy group boundary selection and collapsing scheme, and (3) develop a simple methodology to access the data base to provide rapid solutions to practical shielding problems. This paper describes work carried out to fulfill objective (1), the work consisting of calculations of the transport of fission neutrons through 1- and 2-m-thi… more

Date: January 1, 1982

Creator: Bhuiyan, S. I.; Roussin, R. W. & Lucius, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Resonators for heavily beam-loaded linacs

Capacitively loaded resonant line section accelerating structures are discussed. Prototype models were measured at low levels, and calculations were made to predict high level operation. High current composite beams of multiple-beamlets as accelerated by a MEQALAC were assumed.

Date: April 28, 1980

Creator: Sanders, R.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Nuclear performance calculations for the ELMO Bumpy Torus Reactor (EBTR) reference design

The nuclear performance of the ELMO Bumpy Torus Reactor reference design has been calculated using the one-dimensional discrete ordinates code ANISN and the latest available ENDF/B-IV transport cross-section data and nuclear response functions. The calculated results include estimates of the spatial and integral heating rate with emphasis on the recovery of fusion neutron energy in the blanket assembly and minimization of the energy deposition rates in the cryogenic magnet coil assemblies. The … more

Date: December 1, 1977

Creator: Santoro, R. T. & Barnes, J. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Selective solvent absorption in coal conversion

The objectives of this project are: (1) to determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and (2) to determine the composition of the solvent absorbed by and present within the coal in the first stage of direct coal liquefaction.

Date: April 1, 1992

Creator: Larsen, J. W.; Lapucha, A.; Lazarov, L. & Amui, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Shining On: A primer on solar radiation data

This document is a primer on solar radiation data. General uses of solar energy are presented. The manner in which solar radiation data is used to aid engineers in optimizing the use of solar thermal conversion and photovoltaic conversion is discussed. Methods for acquiring and assimilating the solar radiation data are illustrated. This would include the design and use of pyranometers and pyrheliometers. Seasonal and geographical variations in solar flux reaching the earth are evaluated. Other … more

Date: May 1, 1992

Creator: Dunlap, M.A.; Cook, G. (eds.); Marion, B.; Riordan, C. & Renne, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Emission cross sections and energy extraction for the mid-infrared transitions of Er, Tm, and Ho in oxide and fluoride crystals

Emission cross sections have been measured for the transitions between the two lowest spin orbit multiplets of Er, Tm, and Ho in several fluoride and oxide crystals. Properties affecting energy extraction efficiency are summarized and pulsed extraction performance is calculated for several of these quasi-three-level laser media. 4 refs., 9 figs.

Date: April 1, 1991

Creator: Chase, L. L.; Payne, S. A.; Smith, L. K.; Kway, W. L. & Krupke, W. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanism of pion absorption in complex nuclei

Basic geometrical arguments are used to analyze the A dependence of the total pion absorption cross section, the effective number of nucleons sharing the pion momentum and energy, and the proton yields from ..pi../sup +/- and ..pi../sup -/-induced reactions. The results are consistent with the pions penetrating some distance through the nuclear volume and annihilating on a pair of nucleons. 3 figures.

Date: unknown

Creator: Doss, K.G.N. & Wharton, W.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Long pulse microsphere experiments at 3 TW

Previous 1.06 ..mu..m laser implosion experiments have explored the parameter space associated with microsphere targets of typically less than 100 psec. Exploding pusher experiments have now been performed using long pulses (100 to 200 psec FWHM), and large diameter (100 to 150 ..mu..m) targets on the 3 TW Argus laser facility. Absorption, transport, implosion and neutron and ..cap alpha.. yield characteristics are discussed and compared with earlier short pulse results. The observed neutron yi… more

Date: November 1, 1977

Creator: Boyle, M. J.; Attwood, D. T. & Brooks, K. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department