Microwave interferometer for plasma-density measurement on TMX Upgrade (open access)

Microwave interferometer for plasma-density measurement on TMX Upgrade

A four-channel microwave interferometer operating at 140 GHz has been designed for installation on the upgrade to the Tandem Mirror Experiment (TMX Upgrade). The instrument can be used to measure plasma density simultaneously at four locations: by reconnecting the waveguide runs, density can be measured at other locations of interest. The design is an outgrowth of a system used on TMX, but includes some newly developed hardware. An over-mode circular waveguide system is used to transport the signals over long distances with only moderate losses. Several precautions have been taken to limit the effect of possible interference from the electron cyclotron resonant heating (ECRH) system used to heat the plasma. A high-resolution linear phase comparator has been designed that will operate over the wide range of signals expected. A CAMAC-based data-acquisition system provides for automatic data sampling and archival after each shot.
Date: September 25, 1981
Creator: Coffield, F. E.; Stever, R. D. & Lund, N. P.
System: The UNT Digital Library
Negative deuterium ions for tandem mirror next step and tandem mirror reactors (open access)

Negative deuterium ions for tandem mirror next step and tandem mirror reactors

Recent designs for mirror fusion reactors with good power balance include ambipolar potential plugs to reduce end losses and thermal barriers to maintain a difference in electron temperature between the large-volume central cell plasma and the confining end plugs. These designs led to several new requirements for D/sup 0/ neutral beams derived from negative ions at energies of 150 to 200 keV and possibly higher. Such beams are required for injection of fat ions into the plugs and the barrier and for charge-exchange pumping of thermal ions diffusing into the barrier. Negative ions are preferred for these purposes because of their relatively high efficiency of neutralization and their high purity of single-energy D/sup -/. Examples of injector designs for Tandem Mirror Next Step (TMNS) and Tandem Mirror Reactors (TMR) are presented.
Date: September 25, 1980
Creator: Hamilton, G.W.
System: The UNT Digital Library
Soft x-ray generation by the Cherenkov effect (open access)

Soft x-ray generation by the Cherenkov effect

The Cherenkov effect may be used to generate coherent soft x rays by taking advantage of the dielectric constants of materials in the neighborhood of atomic resonances. The Cherenkov effect usually is not possible for x rays because the refractive index is less than one for most x-ray frequencies. However, for narrow frequency bands near atomic resonances, the refractive index can exceed unity with values large enough to generate coherent x rays with efficiencies higher than any other electron-driven technique. The basic physics of the process is discussed and is used to make rough estimates of photon production efficiencies. An exact theoretical description of Cherenkov production in thin foils is used together with recently-measured refractive indices to calculate the emission distributions of 100 eV photons from thin silicon foils. These distributions are found to be roughly consistent with the simple estimates. In addition, unusual behavior by the distributions suggests a technique that can be used to increase dramatically the peak angular intensities. 15 refs., 10 figs.
Date: February 25, 1987
Creator: Moran, M. J. & Chang, B.
System: The UNT Digital Library
Anomalies in near-threshold photoabsorption: Resonances, ''white-lines'' and other enhancements (open access)

Anomalies in near-threshold photoabsorption: Resonances, ''white-lines'' and other enhancements

Synchrotron measurements of near-threshold and broad-range (80 to 1000 eV) absolute photoabsorption cross sections were taken at Brookhaven using the plane grating monochromator at the VuV storage ring beam line U14A of the NSLS facility. Transmission data for well characterized multilayer foils of C, Ti, Cr, Ni, Cu, Th and U provided absolute cross sections with 10% overall uncertainties and better than 2 eV resolution.
Date: February 25, 1987
Creator: Del Grande, N.K.
System: The UNT Digital Library
The Fermilab upgrade (open access)

The Fermilab upgrade

This paper discusses the upgrades needed at Fermilab Tevatron facility to meet the future physics needs. Historical aspects are also discussed. 3 figs.
Date: September 25, 1988
Creator: Lederman, L.M.
System: The UNT Digital Library
Construction and operation of the 12-T superconducting coils for the Mirror Fusion Test Facility (open access)

Construction and operation of the 12-T superconducting coils for the Mirror Fusion Test Facility

We have successfully constructed and tested a pair of high-field coils that is part of the magnet set of the Mirror Fusion Test Facility (MFTF-B) at the Lawrence Livermore National Laboratory. Each coil consists of a multifilamentary Nb/sub 3/Sn magnet nested inside a multifilamentary NbTi magnet. During our test, these coils produced a central field of 12 T, with a peak conductor field of 12.5 T. The dimensions of the Nb/sub 3/Sn insert coil are: 1.34-m bore, 2.57-m outer diameter, and 1.14-m overall length. These coils were designed to be fully cryogenically stabilized and cooled by pool-boiling liquid helium. The operating current density of the Nb/sub 3/Sn coils is 2000 A/cm/sup 2/ and 2400 A/cm/sup 2/ for the NbTi magnet. In this paper, we present design considerations and details, construction techniques, and operational results of these coils.
Date: September 25, 1986
Creator: Zbasnik, J. P.; Kozman, T. A.; Shimer, D. W. & Hathaway, D. R.
System: The UNT Digital Library
Review of the Advanced Toroidal Facility program (open access)

Review of the Advanced Toroidal Facility program

This report summarizes the history and design goals of the Advanced Toroidal Facility (ATF). The ATF is nearing completion at ORNL with device completion expected in May 1987 and first useful plasma operation in June/July 1987. ATF is a moderate-aspect-ratio torsatron, the world's largest stellarator facility with R = 2.1 m, ..cap alpha.. bar = 0.3 m and B = 2 T (5-s pulse) or 1 T (steady-state capability). It has been specifically designed to support the US tokamak program by studying important toroidal confinement issues in a similar magnetic geometry that allows external control of the magnetic configuration properties and their radial profiles: transform, shear, well depth, shaping, axis topology, etc. ATF will operate in a current-free model which allows separation of current-driven and pressure-driven plasma behavior. It also complements the world stellarator program in its magnetic configuration (between Heliotron-E and W VII-AS) and its capabilities (large size, good access, steady state capability, second stability access, etc.). For both roles ATF will require high-power long-pulse heating to carry out its physics goals since the high power NBI pulse is limited to 0.3 s. The ATF program focuses on demonstrating the principles of high-beta, steady-state operation in toroidal geometry through …
Date: February 25, 1987
Creator: Lyon, J.F. & Murakami, M.
System: The UNT Digital Library
Analysis of multipass laser amplifier systems for storage laser media (open access)

Analysis of multipass laser amplifier systems for storage laser media

The performance characteristics of single pass and multipass storage laser amplifiers are presented and compared. The effects of the multipass amplifier parameters on the extraction characteristics are examined. For a wide range of conditions the multipass amplifier is found to provide high energy gain and high efficiency simultaneously. This is a significant advantage over the single pass laser amplifier. Finally, three specific storage laser amplifier systems, flashlamp pumped V:MgF/sub 2/, XeF laser pumped Tm:Glass, and photolytically pumped Selenium, are examined. The performance characteristics for each of the three systems are calculated and compared.
Date: March 25, 1980
Creator: Harvey, James F.
System: The UNT Digital Library
Nondestructive assay instrumentation for a Savannah River Plant upgrade project (open access)

Nondestructive assay instrumentation for a Savannah River Plant upgrade project

We have designed and are developing three different computer-based spectrometer systems. Two will measure the concentration of Pu solutions by gamma-ray and by stimulated x-ray fluorescence emissions of solid samples in closed containers. All systems are coupled to remote terminals and bar code readers, and also to mini-computer based multichannel analyzers, which in turn are linked to another computer to provide a state-of-the-art nondestructive assay capability. Installation at the Savannah River Plant is planned in late 1985. 7 references.
Date: October 25, 1984
Creator: Camp, D.; Eckels, D.; Gunnink, R.; Prindle, A. & Ruhter, W.
System: The UNT Digital Library
Scaling of laser-plasma interactions with laser wavelength and plasma size (open access)

Scaling of laser-plasma interactions with laser wavelength and plasma size

Plasma size is an important parameter in wavelength-scaling experiments because it determines both the threshold and potential gain for a variety of laser-plasma instabilities. Most experiments to date have of necessity produced relatively small plasmas, due to laser energy and pulse-length limitations. We have discussed in detail three recent Livermore experiments which had large enough plasmas that some instability thresholds were exceeded or approached. Our evidence for Raman scatter, filamentation, and the two-plasmon decay instability needs to be confirmed in experiments which measure several instability signatures simultaneously, and which produce more quantitative information about the local density and temperature profiles than we have today.
Date: January 25, 1983
Creator: Max, C. E.; Campbell, E. M.; Mead, W. C.; Kruer, W. L.; Phillion, D. W.; Turner, R. E. et al.
System: The UNT Digital Library
Angular measurements in optical testing (open access)

Angular measurements in optical testing

The measurement of angles plays an important role in practically every discipline of optics, including prism manufacture, optical assembly and alignment. It is the purpose of this paper to review some of the angle measurement techniques and how they are used in optical testing.
Date: September 25, 1980
Creator: Thomas, N.L.
System: The UNT Digital Library
Recent measurements of coherent transition radiation (open access)

Recent measurements of coherent transition radiation

An extended series of experiments has been used to investigate transition radiation in the x-ray spectral region. The x-rays were generated at the Lawrence Livermore National Laboratory electron-positron linear accelerator by 54 MeV electrons traversing multiple thin-foil targets. The measured angular and spectral distributions have shown excellent agreement with calculated predictions based on a simplified theoretical description of transition radiation. Recently, energy-resolved measurements of x-ray generation by targets consisting of multiple closely-spaced foils has clearly demonstrated the longitudinal coherence of transition radiation. This behavior might lead to a variety of applications such as tuneable narrow-band x-ray sources, measurement of x-ray dielectric constants, or particle beam diagnostics. These issues will be discussed, and recent results will be presented.
Date: September 25, 1986
Creator: Moran, M. J.
System: The UNT Digital Library
Models of optical and soft x-ray spectra in AM Her stars (open access)

Models of optical and soft x-ray spectra in AM Her stars

The AM Her systems are widely believed to be cataclysmic variable systems in which the white dwarf has a magnetic field strong enough to lock the white dwarf to the companion star. The magnetic field channels the accretion flow to the magnetic polar caps of the white dwarf where the gas passes through a strong shock and the accretion energy is released. The continuum spectra of the AM Her systems have three major components: the ir/optical component, the EUV/soft x-ray component, and the hard x-ray component. Models of the AM Her systems generally agree that the hard x-rays are free-free radiation emitted by the hot postshock gas and that the optical component is electron cyclotron emission from the postshock gas. The soft x-ray component is less well understood, primarily because it is very soft (temperature less than 100 eV) and thus is very difficult to measure accurately with current instruments. Models agree that some soft x-ray emission will arise from hard x-rays and cyclotron radiation that is absorbed at the stellar surface and re-radiated, but other sources of soft x-rays have also been suggested. Thus it is important to develop models for the soft x-ray spectrum. This paper presents some …
Date: May 25, 1987
Creator: Langer, S.H.
System: The UNT Digital Library
Radioiodine in kelp from western Australia (open access)

Radioiodine in kelp from western Australia

As part of a program to survey low levels of radioactivity in the marine environment of the southern hemisphere, we have studied the distribution and uptake of /sup 131/I found in the subtidal kelp Ecklonia radiata, on the west coast of Australia. Concentrations of 5 to 75 fCi/g of /sup 131/I exist in this species over a considerable distance along the coast. We have characterized the principal source of the /sup 131/I and found a general temporal correlation between the amount of radioiodine discharged from sewer outfalls and its concentration in kelp. Transplant experiments have enabled us to estimate uptake and depuration rates, and our results are consistent with laboratory measurements made by others.
Date: March 25, 1987
Creator: Marsh, K.V.; Buddemeier, R.W.; Wood, W. & Smith, C.
System: The UNT Digital Library
Synthesis of Accretion Disk and Nonthermal Source Models for AGN (open access)

Synthesis of Accretion Disk and Nonthermal Source Models for AGN

A scenario for the central engine of AGN has been developed consisting of a massive black hole (MBH) onto which gas accretes through an accretion disk. The accretion disk radiates the observed optical and ultraviolet continua. Surrounding the MBH is a nonthermal source which produces the infrared and soft x-ray continua by synchrotron emission, and the x-ray spectrum by inverse Compton scattering of the optical-ultraviolet photons from the accretion disk. Previously we modeled the accretion disk (M.A.M.) and nonthermal source (D.L.B.) separately, and here we combine the two models to form a unified description of the AGN engine. This combined model can be inverted to determine source parameters from observed spectra. A group of AGN for which multiband observations exist can then be modeled to: demonstrate the validity of the combined model for a large number of objects; establish the range of parameter values that describe the source; and search for any correlations between source description and type.
Date: May 25, 1988
Creator: Band, D. L. & Malkan, M. A.
System: The UNT Digital Library
Geothermal Direct Heat Applications Program Summary (open access)

Geothermal Direct Heat Applications Program Summary

Because of the undefined risk in the development and use of geothermal energy as a thermal energy source, the Department of Energy Division of Geothermal Energy solicited competitive proposals for field experiments in the direct use of geothermal energy. Twenty-two proposals were selected for cost-shared funding with one additional project co-funded by the State of New Mexico. As expected, the critical parameter was developing a viable resource. So far, of the twenty resources drilled, fourteen have proved to be useful resources. These are: Boise, Idaho; Elko heating Company in Nevada; Pagosa Springs, Colorado; Philip School, Philip, South Dakota; St. Mary's Hospital, Pierre, South Dakota; Utah Roses near Salt Lake City; Utah State Prison, Utah; Warm Springs State Hospital, Montana; T-H-S Hospital, Marlin, Texas; Aquafarms International in the Cochella Valley, California; Klamath County YMCA and Klamath Falls in Oregon; Susanville, California and Monroe, utah. Monroe's 164 F and 600 gpm peak flow was inadequate for the planned project, but is expected to be used in a private development. Three wells encountered a resource insufficient for an economical project. These were Madison County at Rexburg, Idaho; Ore-Ida Foods at Ontario, Oregon and Holly Sugar at Brawley, California. Three projects have yet to …
Date: September 25, 1981
Creator: unknown
System: The UNT Digital Library
Engineering design of the Nova Laser Facility for inertial-confinement fusion (open access)

Engineering design of the Nova Laser Facility for inertial-confinement fusion

The design of the Nova Laser Facility for inertial confinement fusion experiments at Lawrence Livermore National Laboratory is presented from an engineering perspective. Emphasis is placed upon design-to-performance requirements as they impact the various subsystems that comprise this complex experimental facility.
Date: January 25, 1982
Creator: Simmons, W. W.; Godwin, R. O.; Hurley, C. A.; Wallerstein, E. P.; Whitham, K.; Murray, J. E. et al.
System: The UNT Digital Library
Atomic processes in matter-antimatter interactions (open access)

Atomic processes in matter-antimatter interactions

Atomic processes dominate antiproton stopping in matter at nearly all energies of interest. They significantly influence or determine the antiproton annihilation rate at all energies around or below several MeV. This article reviews what is known about these atomic processes. For stopping above about 10 eV the processes are antiproton-electron collisions, effective at medium keV through high MeV energies, and elastic collisions with atoms and adiabatic ionization of atoms, effective from medium eV through low keB energies. For annihilation above about 10 eV is the enhancement of the antiproton annihilation rate due to the antiproton-nucleus coulomb attraction, effective around and below a few tens of MeV. At about 10 eV and below, the atomic rearrangement/annihilation process determines both the stopping and annihilation rates. Although a fair amount of theoretical and some experimental work relevant to these processes exist, there are a number of energy ranges and material types for which experimental data does not exist and for which the theoretical information is not as well grounded or as accurate as desired. Additional experimental and theoretical work is required for accurate prediction of antiproton stopping and annihilation for energies and material relevant to antiproton experimentation and application.
Date: January 25, 1988
Creator: Morgan, D. L.
System: The UNT Digital Library
MAGRAC: railgun simulation program (open access)

MAGRAC: railgun simulation program

A computer simulation code at the Lawrence Livermore National Laboratory (LLNL) to predict the performance of a railgun electromagnetic accelerator has been developed and validated. The code, called MAGRAC (MAGnetic Railgun ACcelerator), models the performance of a railgun driven by a magnetic flux compression current generator (MFCG). The MAGRAC code employs a time-step solution of the nonlinear time-varying element railgun circuit to determine rail currents. From the rail currents, the projectile acceleration, velocity, and position are found. The MAGRAC code was validated through a series of eight railgun tests conducted jointly with the Los Alamos National Laboratory. The formulation of the MAGRAC railgun model is described and the predicted current waveforms compared with those obtained from full-scale experiments.
Date: March 25, 1981
Creator: Deadrick, F. J.; Hawke, R. S. & Scudder, J. K.
System: The UNT Digital Library
Comparison of observed and predicted Kr-85 air concentrations (open access)

Comparison of observed and predicted Kr-85 air concentrations

A computer code, ANEMOS has been written to estimate concentrations in air and ground deposition rates for Atmospheric Nuclides Emitted from Multiple Operation Sources. This code uses a modified Gaussian plum equation. Output from ANEMOS includes annual-average air concentrations and ground deposition rates of dispersed radionuclides and daughters. To use the environmental transport model properly, some estimate of the models predictive accuracy must be obtained. To validate the ANEMOS model, one year of weekly average Kr-85 concentrations observed at 13 stations located 28 to 144 km distant from continuous point source at the Savannah River Plant (SRP), Aiken, South Carolina, have been used. There was a general tendency for the model to underpredict the observed air concentrations slightly. Pearsons's correlation between pairs of logarithms of observed and predicted annual-average values was r = 0.84. The monthly results tend to show more scatter than do either the seasonal or the annual comparisons. 18 references, 3 figures, 3 tables.
Date: April 25, 1984
Creator: Yildiran, M. & Miller, C. W.
System: The UNT Digital Library
AI/Simulation Fusion Project at Lawrence Livermore National Laboratory (open access)

AI/Simulation Fusion Project at Lawrence Livermore National Laboratory

This presentation first discusses the motivation for the AI Simulation Fusion project. After discussing very briefly what expert systems are in general, what object oriented languages are in general, and some observed features of typical combat simulations, it discusses why putting together artificial intelligence and combat simulation makes sense. We then talk about the first demonstration goal for this fusion project.
Date: April 25, 1984
Creator: Erickson, S.A.
System: The UNT Digital Library
Linear pinch driven by a moving compact torus (open access)

Linear pinch driven by a moving compact torus

In principle, a Z-pinch of sufficiently large aspect ratio can provide arbitrarily high magnetic field intensity for the confinement of plasma. In practice, however, achievable field intensities and timescales are limited by parasitic inductances, pulse driver power, current, voltage, and voltage standoff of nearby insulating surfaces or surrounding gas. Further, instabilities may dominate to prevent high fields (kink mode) or enhance them (sausage mode) but in a nonuniform and uncontrollable way. In this paper we discuss an approach to producing a high-field-intensity pinch using a moving compact torus. The moving torus can serve as a very high power driver and may be used to compress a pre-established pinch field, switch on an accelerating pinch field, or may itself be reconfigured to form an intense pinch. In any case, the high energy, high energy density, and high velocity possible with an accelerated compact torus can provide extremely high power to overcome, by a number of orders of magnitude, the limitations to pinch formation described earlier. In this paper we will consider in detail pinches formed by reconfiguration of the compact torus.
Date: April 25, 1984
Creator: Hartman, C. W.; Hammer, J. H. & Eddleman, J. L.
System: The UNT Digital Library
Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors (open access)

Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors

Current designs for compact tokamak reactors require the toroidal- field (TF) superconducting magnets to produce fields from 10 to 15 T at the winding pack, using high-current densities to high nuclear heat loads (greater than 1 kW/coil in some instances), which are significantly greater than the conduction and radiation heat loads for which cryogenic systems are usually designed. A cryogenic system for the TF winding pack for two such tokamak designs has been verified by performing a detailed, steady-state heat-removal analysis. Helium properties along the forced-cooled conductor flow path for a range of nuclear heat loads have been calculated. The results and implications of this analysis are presented. 12 refs., 6 figs.
Date: October 25, 1988
Creator: Kerns, J. A.; Slack, D. S. & Miller, J. R.
System: The UNT Digital Library
Electron-Impact Ionization Data for the Fe Isonuclear Sequence (open access)

Electron-Impact Ionization Data for the Fe Isonuclear Sequence

Atomic data for the electron-impact ionization of ions in the Fe isonuclear sequence is reviewed. The best available data are identified. Comments are made on current research activities leading to future data for Fe ions. 23 refs., 29 figs., 12 tabs.
Date: November 25, 1986
Creator: Pindzola, M. S.; Griffin, D. C.; Bottcher, C.; Younger, S. M. & Hunter, H. T.
System: The UNT Digital Library