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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 (open access)

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. Comparisons of these results with the gain survey of Part I would have to be performed with care. These calculations suggest that experiments relating to high temperature disk heating, as well as beam deposition, focusing and transport can be performed within the context of current design proposals for accelerator test-facilities. Since the test-facilities have lower ion kinetic energy and beam pulse power as compared to reactor drivers, we achieve high-beam intensities at the focal spot by using short focal distance and properly designed beam optics.
Date: June 24, 1982
Creator: Mark, J.W.K.
System: The UNT Digital Library
Time-Dependent Two-Dimensional Radiation Hydrodynamics of Accreting Matter Onto Highly Magnetized Neutron Stars (open access)

Time-Dependent Two-Dimensional Radiation Hydrodynamics of Accreting Matter Onto Highly Magnetized Neutron Stars

We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations show a structure in the accretion column very different from previous one-zone uniform models. We have included all the relevant magnetic field corrections to both the hydrodynamics and the radiative transport. We include a new theory for the diffusion and advection of both radiation energy density and photon number density. For initially uniformly accreting models with super-Eddington flows, we have uncovered evidence of strong radiation-driven outflowing optically thin radiation filled regions of the accretion column embedded in optically-thick inflowing plasma. The development of these photon bubbles'' have growth times on the order of a millisecond and show fluctuations on sub-millisecond timescales. The photon bubbles are likely to be a consequence of convective over-stability and may result in observable fluctuations in the emitted luminosity leading to luminosity dependent changes in the pulse profile. This may provide important new diagnostics for conditions in accreting x-ray pulsars. 13 refs., 18 figs.
Date: November 24, 1989
Creator: Klein, R.I. (California Univ., Los Angeles, CA (USA). Dept. of Astronomy Lawrence Livermore National Lab., CA (USA) California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics) & Arons, J. (California Univ., Berkeley, CA (USA). Dept. of Astronomy California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics CEA Centre d'Etudes Nucleaires de Saclay, 91 -
System: The UNT Digital Library
/sup 56/Ni and the light curve of Type I supernova (open access)

/sup 56/Ni and the light curve of Type I supernova

The explanation of SN Type I by radioactive decay of /sup 56/Ni requires a relatively small value of the transparency function M/sub ej//v/sub 9//sup 2/ = 0.22 in units of M/sub solar/'s and 10/sup 9/ cm s/sup -1/ to explain the light curve. A minimum mass of /sup 56/Ni is required to explain the peak and near peak luminosity. Subsequent radioactive decay energy must escape in some other form than optical light in order to explain the rapid early and late time decay. Early ultraviolet and infrared radiation are excluded as sinks of energy by observations. PdV work is excluded by theory. The energy loss due to the escape of gamma rays and ..beta../sup +/'s with the above value of M/sub ej//v/sub 9//sup 2/ gives good agreement with the light curve after maximum, provided essentially all the trapped energy is converted to optical light. The peak of SN 1972e is explained with the above transparency value M/sub ej//v/sub 9//sup 2/ = 0.22 and mass of /sup 56/Ni of 0.25 M/sub solar/ or 0.4 M/sub solar/, and a distance of 3.2 Mpc or 4 Mpc, respectively. These values depend critically upon the prediscovery report of Austin (1972), and the assumption again …
Date: July 24, 1980
Creator: Colgate, S.A. & Petschek, A.G.
System: The UNT Digital Library
Evaluation of soil damping techniques used in soil structure interaction analysis of a nuclear power plant (open access)

Evaluation of soil damping techniques used in soil structure interaction analysis of a nuclear power plant

A prediction of dynamic soil properties at the site of a nuclear power plant plays a very important role in the seismic analysis of the facility. Conventional modal analysis procedures can accommodate virtually any range of equivalent elastic soil stiffness which is used to characterize the site. However, high radiation damping associated with energy dissipation in the soil half-space is difficult to accommodate in an elastic modal solution to the dynamic problem. Several methods are available to combine the soil damping with the structural damping in a composite modal damping coefficient. However, even with this convenient representation, the resulting large fractions of critical damping can make modal solutions to the problems suspect. This paper is based on experience gained in this area during studies performed for the Nuclear Regulatory Commission involving seismic analyses of power plants.
Date: February 24, 1982
Creator: Nelson, T.A.
System: The UNT Digital Library
Scale effects in sliding friction: An experimental study (open access)

Scale effects in sliding friction: An experimental study

Solid friction is considered by some to be a fundamental property of two contacting materials, while others consider it to be a property of the larger tribosystem in which the materials are contained. A set of sliding friction experiments were designed to investigate the hypothesis that the unlubricated sliding friction between two materials is indeed a tribosystems-related property and that the relative influence of the materials properties or those of the machine on friction varies from one situation to another. Three tribometers were used: a friction microprobe (FMP), a typical laboratory-scale reciprocating pin-on-flat device, and a heavy-duty commercial wear tester. The slider material was stainless steel (AISI 440C) and the flat specimen material was an ordered alloy of Ni{sub 3}Al (IC-50). Sphere-on-flat geometry was used at ambient conditions and at normal forces ranging from 0.01 N to 100 N and average sliding velocities of 0.01 to 100.0 mm/s. The nominal, steady-state sliding friction coefficient tended to decrease with increases in normal force for each of the three tribometers, and the steady state value of sliding friction tended to increase as the mass of the machine increased. The variation of the friction force during sliding was also a characteristic of the …
Date: July 24, 1991
Creator: Blau, P.J.
System: The UNT Digital Library
Energy balance measurements for Shiva (open access)

Energy balance measurements for Shiva

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 beam input holes. This measurement prevents the use of other diagnostics, so for normal operation an energy balance module was designed for location on ports on the Shiva target chamber. This module monitors the energy in scattered light at 10640 A and 5320 A or 7118 A. It also contains a faraday cup and plasma and x-ray calorimeters. The distribution of energy in scattered light, plasma and x-rays will be mapped by 58 such modules.
Date: October 24, 1977
Creator: Glaros, S.S.; Rupert, V.C.; Gunn, S.R.; Phillion, D.W. & Kornblum, H.N.
System: The UNT Digital Library
Nuclear interactions of heavy ions (open access)

Nuclear interactions of heavy ions

A possible source of preheat for heavy ion driven inertial fusion targets is the production of fast precursors by nuclear interactions between the incident heavy ions and the outer parts of the target. A model has been developed which roughly describes these interactions for all beam-target combinations for all incident energies. This interaction model has been applied to a specific capsule design. The resultant preheat is an order of magnitude below the level which could impair target performance.
Date: February 24, 1982
Creator: Tabak, M. & Bangerter, R.
System: The UNT Digital Library
Geothermal Symposium: Low-Temperature Utilization, Heat-Pump Applications, District Heating (open access)

Geothermal Symposium: Low-Temperature Utilization, Heat-Pump Applications, District Heating

Separate abstracts are prepared for twelve papers presented at the symposium. (MCW)
Date: September 24, 1980
Creator: Bloomquist, R. G.
System: The UNT Digital Library
Wear and corrosion performance of metallurgical coatings in sodium (open access)

Wear and corrosion performance of metallurgical coatings in sodium

The friction, wear, and corrosion performance of several metallurgical coatings in 200 to 650/sup 0/C sodium are reviewed. Emphasis is placed on those coatings which have successfully passed the qualification tests necessary for acceptance in breeder reactor environments. Tests include friction, wear, corrosion, thermal cycling, self-welding, and irradiation exposure under as-prototypic-as-possible service conditions. Materials tested were coatings of various refractory metal carbides in metallic binders, nickel-base and cobalt-base alloys and intermetallic compounds such as the aluminides and borides. Coating processes evaluated included plasma spray, detonation gun, sputtering, spark-deposition, and solid-state diffusion.
Date: April 24, 1980
Creator: Johnson, R. N. & Farwick, D. G.
System: The UNT Digital Library
Shiva optical diagnostics (open access)

Shiva optical diagnostics

In the laser fusion program at Lawrence Livermore Laboratory, no target experiment is complete unless it is complemented by careful measurements of the laser pulse that irradiates the target. For this purpose, an incident beam diagnostics (IBD) package has been designed for the Shiva laser. The package will furnish data on items such as the total energy and the focusable energy out of the laser chain, and the spatial and temporal energy and power distribution at the target plane. Understanding laser-plasma interactions requires knowledge of the amount of 1.06 ..mu..m light energy that is scattered in various directions from the target. The light energy that is scattered toward the beam focusing lens is analyzed by a reflected beam diagnostic (RBD) package containing a calorimeter, a multiple image camera and a TV camera. This paper describes the detailed design and operation of the IBD and RBD packages as tools to align spatial filters and targets, as well as to diagnose the laser beams and target reflectivity.
Date: October 24, 1977
Creator: Rienecker, F.; Kobierecki, M.; Ozarski, R.; Seppala, L.; Manes, K. & Merritt, B.
System: The UNT Digital Library
Mechanical design of the Tandem Mirror Experiment Upgrade vacuum system (open access)

Mechanical design of the Tandem Mirror Experiment Upgrade vacuum system

The Tandem Mirror Experiment Upgrade (TMX Upgrade) vacuum system uses most of the vacuum system from the original TMX and substantially increases its capabilities. The vacuum system provides the main structure for the experimental apparatus, as well as providing and maintaining the vacuum environment. The vacuum vessel provides the structure supporting all magnets, as they are contained inside the vacuum vessel, all of the neutral-beam injectors, and the various diagnostics. The vessel provides the main vacuum enclosure and the various access ports required by the magnet system, injector system, internal vacuum system, and plasma diagnostics. The vacuum environment is created and maintained by two systems, the external vacuum system and the internal vacuum system. The external system consists of mechanical pumps, turbopumps, and cryopumps, and creates a vacuum inside the vessel down to a minimum pressure of 10/sup -6/ Torr. The internal vacuum system further reduces the pressure into the 10/sup -8/ Torr range and provides the fast pumping required to handle the excess gas from the neutral-beam injector system during a plasma shot. The internal vacuum system consists of titanium sublimators and liquid nitrogen (LN) liners that separate the vacuum vessel into various pumping regions.
Date: September 24, 1981
Creator: Lang, D. D.; Calderon, M. O.; Thomas, S. R. & Garner, D. R.
System: The UNT Digital Library
Early history of computer simulations in statistical mechanics (open access)

Early history of computer simulations in statistical mechanics

A history of the early use of the Monte Carlo method is presented.
Date: June 24, 1985
Creator: Wood, W.W.
System: The UNT Digital Library
Hadron masses in lattice gauge theories: The inclusions of dynamical fermions (open access)

Hadron masses in lattice gauge theories: The inclusions of dynamical fermions

Hadron masses are calculated on an 8/sup 3/ /times/ 16 lattice using four flavors of staggered fermion to generate the gauge configurations, but using Wilson fermions to calculate the hadron propagators. The identification of a value of the Wilson hopping parameter with the value of the bare quark mass used in the simulations is discussed.
Date: November 24, 1987
Creator: Richards, D.G.
System: The UNT Digital Library
Tandem mirror fusion-fission hybrid studies (open access)

Tandem mirror fusion-fission hybrid studies

Initial tandem mirror hybrid studies predict the ability to produce large amounts of fissile fuel (2 to 7 tons U233 per year from a 4000 MW plant) at a cost that adds less than 25% to the cost of power from a LWR.
Date: April 24, 1980
Creator: Lee, J. D.
System: The UNT Digital Library
High performance inertial fusion targets (open access)

High performance inertial fusion targets

Inertial confinement fusion (ICF) designs are considered which may have very high gains (approximately 1000) and low power requirements (<100 TW) for input energies of approximately one megajoule. These include targets having very low density shells, ultra thin shells, central ignitors, magnetic insulation, and non-ablative acceleration.
Date: August 24, 1977
Creator: Nuckolls, J.H.; Bangerter, R.O.; Lindl, J.D.; Mead, W.C. & Pan, Y.L.
System: The UNT Digital Library
Pion induced double-charge exchange above the resonance (open access)

Pion induced double-charge exchange above the resonance

The zero degree excitation function for ({pi}{sup +}, {pi}{sup -}) is calculated for pion energies of 300 to 1400 MeV assuming a sequential mechanism. The cross section around 1225 MeV is 10{sup 4} smaller than at 800 MeV. Experiments at this energy should be ideal for searches for effects due to exchange currents, and other non-conventional mechanisms. 15 refs.
Date: October 24, 1989
Creator: Oset, E.; Strottman, D. (Valencia Univ. (Spain). Dept. de Fisica Teorica & Los Alamos National Lab., NM (USA))
System: The UNT Digital Library
Optical coatings for laser fusion applications (open access)

Optical coatings for laser fusion applications

Lasers for fusion experiments use thin-film dielectric coatings for reflecting, antireflecting and polarizing surface elements. Coatings are most important to the Nd:glass laser application. The most important requirements of these coatings are accuracy of the average value of reflectance and transmission, uniformity of amplitude and phase front of the reflected or transmitted light, and laser damage threshold. Damage resistance strongly affects the laser's design and performance. The success of advanced lasers for future experiments and for reactor applications requires significant developments in damage resistant coatings for ultraviolet laser radiation.
Date: April 24, 1980
Creator: Lowdermilk, W.H.; Milam, D. & Rainer, F.
System: The UNT Digital Library
Simulations of intermediate density laser fusion targets: recent progress in design and analysis (open access)

Simulations of intermediate density laser fusion targets: recent progress in design and analysis

The attainment of low-adiabat compression to high final state density is essential for achieving high gain thermonuclear micro-implosions. Using 1- and 2-dimensional numerical simulations with LASNEX, the target performance which can be expected and the limitations imposed by absorption heating, and transport for targets designed to reach 100 x liquid DT density (20g/cm/sup 3/) are discussed. The requirements imposed by the need for low preheat, adequate implosion symmetry, and the behavior of fluid instabilities are discussed for these recent target designs. Methods for diagnosis of density are discussed.
Date: August 24, 1977
Creator: Mead, W. C.; Lindl, J. D.; Nuckolls, J. H.; Larsen, J. T.; Bailey, D. S. & Pan, Y. L.
System: The UNT Digital Library
Multiple electron capture in close ion-atom collisions (open access)

Multiple electron capture in close ion-atom collisions

Collisions in which a fast highly charged ion passes within the orbit of K electron of a target gas atom are selected by emission of a K x-ray from the projectile or target. Measurement of the projectile charge state after the collision, in coincidence with the K x-ray, allows measurement of the charge-transfer probability during these close collisions. When the projectile velocity is approximately the same as that of target electrons, a large number of electrons can be transferred to the projectile in a single collision. The electron-capture probability is found to be a linear function of the number of vacancies in the projectile L shell for 47-MeV calcium ions in an Ar target. 18 refs., 9 figs.
Date: July 24, 1989
Creator: Schlachter, A. S.; Stearns, J. W.; Berkner, K. H.; Bernstein, E. M.; Clark, M. W.; DuBois, R. D. et al.
System: The UNT Digital Library
Modeling of transformation toughening in brittle materials (open access)

Modeling of transformation toughening in brittle materials

Results from modeling of transformation toughening in brittle materials using a discrete micromechanical model are presented. The material is represented as a two-dimensional triangular array of nodes connected by elastic springs. Microstructural effects are included by varying the spring parameters for the bulk, grain boundaries, and transforming particles. Using the width of the damage zone and the effective compliance (after the initial creation of the damage zone) as measures of fracture toughness, we find that there is a strong dependence of toughness on the amount, size, and shape of the transforming particles, with the maximum toughness achieved with the higher amounts of the larger particles.
Date: January 24, 1992
Creator: LeSar, R.; Rollett, A.D. (Los Alamos National Lab., NM (United States)) & Srolovitz, D.J. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Materials Science and Engineering)
System: The UNT Digital Library
Analysis of dense pusher laser-driven implosions for intermediate densities (open access)

Analysis of dense pusher laser-driven implosions for intermediate densities

Post-shot analysis of targets designed to achieve a diagnosible compression of DT gas to 2. g/cm/sup 3/ or 10 x liquid density is reported. The SHIVA laser provided 15 to 20 TW of 1.06 ..mu..m laser light. Detailed comparisons of diagnostic results with hydro-code calculations are made. Implications for laser light absorption/scattering, thermal conduction, suprathermal electron preheat, implosion symmetry, and pusher-fuel mix are discussed. Uncertainties of the density determination methods are analyzed. Good overall consistency is found, indicating strong support for the successful attainment of 1.-3. g/cm/sup 3/.
Date: October 24, 1979
Creator: Mead, W. C.; Orth, C. D.; Bailey, D. S.; McClellan, G. & Estabrook, K. G.
System: The UNT Digital Library
Temporal Complexity of the Order Parameter at the Phase Transition (open access)

Temporal Complexity of the Order Parameter at the Phase Transition

Article discussing the temporal complexity of the order parameter at the phase transition.
Date: June 24, 2011
Creator: Turalska, Malgorzata; West, Bruce J. & Grigolini, Paolo
System: The UNT Digital Library
Extending the cereus group genomics to putative food-borne pathogens of different toxicity (open access)

Extending the cereus group genomics to putative food-borne pathogens of different toxicity

The cereus group represents sporulating soil bacteriacontaining pathogenic strains which may cause diarrheic or emetic foodpoisoning outbreaks. Multiple locus sequence typing revealed a presencein natural samples of these bacteria of about thirty clonal complexes.Application of genomic methods to this group was however biased due tothe major interest for representatives closely related to B. anthracis.Albeit the most important food-borne pathogens were not yet defined,existing dataindicate that they are scattered all over the phylogenetictree. The preliminary analysis of the sequences of three genomesdiscussed in this paper narrows down the gaps in our knowledge of thecereus group. The strain NVH391-98 is a rare but particularly severefood-borne pathogen. Sequencing revealed that the strain must be arepresentative of a novel bacterial species, for which the name Bacilluscytotoxis is proposed. This strain has a reduced genome size compared toother cereus group strains. Genome analysis revealed absence of sigma Bfactor and the presence of genes encoding diarrheic Nhe toxin, notdetected earlier. The strain B. cereus F837/76 represents a clonalcomplex close to that of B. anthracis. Including F837/76, three such B.cereus strains had been sequenced. Alignment of genomes suggests that B.anthracis is their common ancestor. Since such strains often emerge fromclinical cases, they merit a special attention. The …
Date: August 24, 2006
Creator: Lapidus, Alla; Goltsman, Eugene; Auger, Sandrine; Galleron, Nathalie; Segurens, Beatrice; Dossat, Carole et al.
System: The UNT Digital Library
On the Virial Theorem for Interstellar Medium (open access)

On the Virial Theorem for Interstellar Medium

An attempt has been made to derive a version of the virial integral that would describe average properties of the interstellar medium (ISM). It is suggested to eliminate the (large) contribution of stellar matter by introducing 'exclusion zones' surrounding stars. Such an approach leads to the appearance of several types of additional surface integrals in the general expression. Their contribution depends on the rate of energy and matter exchange between the stars and ISM. If this exchange is weak, one can obtain a desired virial integral for ISM. However, the presence of intermittent large-scale energetic events significantly constrains the applicability of the virial theorem. If valid, the derived virial integral is dominated by cold molecular/atomic clouds, with only minor contribution of the global magnetic field and low-density warm part.
Date: September 24, 2007
Creator: Ryutov, D.
System: The UNT Digital Library