The use of a permanent magnet for water content measurements ofwood chips (open access)

The use of a permanent magnet for water content measurements ofwood chips

The Lawrence Berkeley National Laboratory has developed a device that measures the water content of wood chips, pulp and brown stock for the paper industry. This device employs a permanent magnet as the central part of a NMR measurement system. This report describes the magnet and the NMR measurement system. The results of water content measurements in wood chips in a magnetic field of 0.47 T are presented.
Date: September 20, 2001
Creator: Barale, P. J.; Fong, C. G.; Green, M. A.; Luft, P. A.; McInturff, A. D.; Reimer, J. A. et al.
System: The UNT Digital Library
High-Resolution Adaptive Optics Test-Bed for Vision Science (open access)

High-Resolution Adaptive Optics Test-Bed for Vision Science

We discuss the design and implementation of a low-cost, high-resolution adaptive optics test-bed for vision research. It is well known that high-order aberrations in the human eye reduce optical resolution and limit visual acuity. However, the effects of aberration-free eyesight on vision are only now beginning to be studied using adaptive optics to sense and correct the aberrations in the eye. We are developing a high-resolution adaptive optics system for this purpose using a Hamamatsu Parallel Aligned Nematic Liquid Crystal Spatial Light Modulator. Phase-wrapping is used to extend the effective stroke of the device, and the wavefront sensing and wavefront correction are done at different wavelengths. Issues associated with these techniques will be discussed.
Date: September 27, 2001
Creator: Wilks, S. C.; Thomspon, C. A.; Olivier, S. S.; Bauman, B. J.; Barnes, T. & Werner, J. S.
System: The UNT Digital Library
RF Gas Plasma Source Development for Heavy Ion Fusion (open access)

RF Gas Plasma Source Development for Heavy Ion Fusion

Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50-2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamlets ion temperature is below a few eV. Thus, a RF multicusp source capable of high current density can produce beams with better brightness compared to ones extracted from a colder source with a large aperture and lower current density. As such, experiments have begun to develop a RF multicusp source capable of delivering one amp of extracted beam current. It is expected that it will require 10 kW of 13 MHz RF power delivered via a quartz shielded, one and half turn, four inch diameter antenna. Important considerations in the development of the source include the dependence of current density and beam ion temperature on consumed RF power and gas pressure. A fast rise time ({approx} 100 ns) for the extracted beam pulse must …
Date: September 4, 2001
Creator: Ahle, L.; Hall, R. P.; Molvik, A. W.; Kwan, J. W. & Leung, K. N.
System: The UNT Digital Library
Infrared Spectra of High Pressure Carbon Monoxide (open access)

Infrared Spectra of High Pressure Carbon Monoxide

We report infrared (IR) spectroscopic measurements of carbon monoxide (CO) at high pressures. Although CO is one of the simplest heteronuclear diatomic molecules, it displays surprisingly complex behavior at high pressures and has been the subject of several studies [1-5]. IR spectroscopic studies of high pressures phases of CO provide data complementing results from previous studies and elucidating the nature of these phases. Though a well-known and widely utilized diagnostic of molecular systems, IR spectroscopy presents several experimental challenges to high pressure diamond anvil cell research. We present measurements of the IR absorption bands of CO at high pressures and experimentally illustrate the crucial importance of accurate normalization of IR spectra specially within regions of strong absorptions in diamond.
Date: September 21, 2001
Creator: Evans, W. J.; Lipp, M. J. & Lorenzana, H. E.
System: The UNT Digital Library
Theory Issues for Induced Plasma Convection Experiments in the Divertor of the MAST Spherical Tokamak (open access)

Theory Issues for Induced Plasma Convection Experiments in the Divertor of the MAST Spherical Tokamak

This paper surveys theory issues associated with inducing convective cells through divertor tile biasing in a tokamak to broaden the scrape-off layer (SOL). The theory is applied to the Mega-Ampere Spherical Tokamak (MAST), where such experiments are planned in the near future. Criteria are presented for achieving strong broadening and for exciting shear-flow turbulence in the SOL; these criteria are shown to be attainable in practice. It is also shown that the magnetic shear present in the vicinity of the X-point is likely to confine the potential perturbations to the divertor region below the X-point, leaving the part of the SOL that is in direct contact with the core plasma intact. The current created by the biasing and the associated heating power are found to be modest.
Date: September 5, 2001
Creator: Cohen, R. H.; Fielding, S.; Helander, P. & Ryutov, D. D.
System: The UNT Digital Library
On the Development of Microstructure in a Metal Matrix Composite Using Nano-Materials (open access)

On the Development of Microstructure in a Metal Matrix Composite Using Nano-Materials

Metal matrix composites (MMCs) containing matrices with nanometer grain sizes have been produced from pure aluminum nano-powders (particle sizes 50-200 nm) with SiC reinforcement (particle sizes 3-10 {micro}m). The pure Al nano-powders were produced using an exploding wire technique. Dynamic loading using a magnetic impulse technique has been used to compact the MMC to high density. The dynamic compaction process results in excellent wetting of the SiC particles by the nanocrystalline Al powders, and the retention of a nano-crystalline grain size in the MMC. Microstructural analysis of the resulting MMC showed a highly uniform distribution of Sic particles with no visible defects or pores and the absence of deleterious phases (such as Al{sub 4}C{sub 3}) at the interfaces between the aluminum nano-grains and the SiC particles. The microstructures produced and the evolution of microstructure during dynamic compaction has also been studied using TEM and found to progress in three stages. These three stages are described.
Date: September 10, 2001
Creator: Popov, V A; Lesuer, D R; Kotov, I A; Ivanov, V V; Aksenov, A A; Khodos, I I et al.
System: The UNT Digital Library
Technical Advances in the Continuous Melting of Phosphate Laser Glass (open access)

Technical Advances in the Continuous Melting of Phosphate Laser Glass

Continuous melting of phosphate laser glass is now being used for the first time to prepare meter-scale amplifier optics for megajoule lasers. The scale-up to continuous melting from the previous one-at-a-time ''discontinuous'' batch process has allowed for the production of glass at rates more than 20 times faster, 5 times cheaper, and with 2-3 times better optical quality. Almost 8000 slabs of laser glass will be used in high-energy, high-peak-power laser systems that are being designed and built for fusion energy research. The success of this new continuous melting process, which is a result of a six year joint R&D program between government and industry, stems from numerous technical advances which include (1) dehydroxylating the glass to concentrations less than {approx}100 ppm OH; (2) minimizing damage-causing Pt-inclusions; (3) preventing glass fracture; (4) minimizing impurities such as Cu and Fe to <20 ppm; (5) improving forming methods to get high optical homogeneity glass; and (6) developing large aperture quality assurance tools to verify properties of the glass.
Date: September 5, 2001
Creator: Suratwala, T.; Thorsness, C.; Campbell, J.; Takeuchi, K.; Suzuki, K.; Yamamoto, K. et al.
System: The UNT Digital Library
Overview and Status of the Power Conditioning System for the National Ignition Facility (open access)

Overview and Status of the Power Conditioning System for the National Ignition Facility

The National Ignition Facility (NIF) Power Conditioning System (PCS) is a modular capacitive energy storage system that provides over 34 kilojoules of energy to each of the nearly 8000 flashlamps in the NIF laser. Up to 400 megajoules of energy can be stored in the NIF PCS system, discharged through spark gaps and delivered to the flashlamps through a coaxial transmission line system requiring nearly 100 miles of high-voltage cable. The NIF PCS has been under development for nearly 4 years. During this time, the system was developed and designed by Sandia National Laboratory in Albuquerque, NM (SNLA) in conjunction with Lawrence Livermore National Laboratory (LLNL). Extensive reliability testing was performed at SNLA on the First Article NIF Test Module (FANTM) test facility and design improvements were implemented based on FANTM test results, leading to the final design presently undergoing system reliability testing at LLNL. Low-cost energy-storage capacitors, charging power supplies, and reliable, fault-tolerant components were developed through partnerships with numerous contractors. Extensive reliability and fault testing of components has also been performed. This paper will provide an overview of the many efforts that have culminated in the final design of the NIF PCS. The PCS system design will be …
Date: September 11, 2001
Creator: Newton, M A; Fulkerson, E S; Hulsey, S D; Kamm, R E; Pendleton, D L; Petersen, D E et al.
System: The UNT Digital Library
Recent X-Ray Laser Experiments on the COMET Facility (open access)

Recent X-Ray Laser Experiments on the COMET Facility

The development of the transient collisional excitation x-ray laser scheme using tabletop laser systems with multiple pulse capability has progressed rapidly in the last three years. The high small-signal gain and strong x-ray output have been demonstrated for laser drive energies of typically less than 10 J. We report recent x-ray laser experiments on the Lawrence Livermore National Laboratory (LLNL) Compact Multipulse Terawatt (COMET) tabletop facility using this technique. In particular, the saturated output from the Ni-like Pd ion 4d - 4p x-ray laser at 146.8 {angstrom} has been well characterized and has potential towards a useable x-ray source in a number of applications. One important application of a short wavelength x-ray laser beam with picosecond pulse duration is the study of a high density laser-produced plasma. We report the implementation of a Mach-Zehnder type interferometer using diffraction grating optics as beam splitters designed for the Ni-like Pd laser and show results from probing a 600 ps heated plasma. In addition, gas puff targets are investigated as an x-ray laser gain medium and we report results of strong lasing on the n = 3 - 3 transitions of Ne-like Ar.
Date: September 22, 2001
Creator: Dunn, J.; Smith, R. F.; Nilsen, J.; Hunter, J. R.; Barbee, T. W.; Shlyaptsev, V. N. et al.
System: The UNT Digital Library
Advanced Adaptive Optics Technology Development (open access)

Advanced Adaptive Optics Technology Development

The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.
Date: September 18, 2001
Creator: Olivier, S.
System: The UNT Digital Library
Inertial Fusion and High-Energy-Density Science in the United States (open access)

Inertial Fusion and High-Energy-Density Science in the United States

Inertial fusion and high-energy density science worldwide is poised to take a great leap forward. In the US, programs at the University of Rochester, Sandia National Laboratories, Los Alamos National Laboratory, Lawrence Livermore National Laboratory (LLNL), the Naval Research Laboratory, and many smaller laboratories have laid the groundwork for building a facility in which fusion ignition can be studied in the laboratory for the first time. The National Ignition Facility (NIF) is being built by the Department of Energy's National Nuclear Security Agency to provide an experimental test bed for the US Stockpile Stewardship Program (SSP) to ensure the dependability of the country's nuclear deterrent without underground nuclear testing. NIF and other large laser systems being planned such as the Laser MegaJoule (LMJ) in France will also make important contributions to basic science, the development of inertial fusion energy, and other scientific and technological endeavors. NIF will be able to produce extreme temperatures and pressures in matter. This will allow simulating astrophysical phenomena (on a tiny scale) and measuring the equation of state of material under conditions that exist in planetary cores.
Date: September 6, 2001
Creator: Tarter, C B
System: The UNT Digital Library
RECENT ACTIVITIES AT THE CENTER FOR SPACE NUCLEAR RESEARCH FOR DEVELOPING NUCLEAR THERMAL ROCKETS (open access)

RECENT ACTIVITIES AT THE CENTER FOR SPACE NUCLEAR RESEARCH FOR DEVELOPING NUCLEAR THERMAL ROCKETS

Nuclear power has been considered for space applications since the 1960s. Between 1955 and 1972 the US built and tested over twenty nuclear reactors/ rocket-engines in the Rover/NERVA programs. However, changes in environmental laws may make the redevelopment of the nuclear rocket more difficult. Recent advances in fuel fabrication and testing options indicate that a nuclear rocket with a fuel form significantly different from NERVA may be needed to ensure public support. The Center for Space Nuclear Research (CSNR) is pursuing development of tungsten based fuels for use in a NTR, for a surface power reactor, and to encapsulate radioisotope power sources. The CSNR Summer Fellows program has investigated the feasibility of several missions enabled by the NTR. The potential mission benefits of a nuclear rocket, historical achievements of the previous programs, and recent investigations into alternatives in design and materials for future systems will be discussed.
Date: September 1, 2001
Creator: O'Brien, Robert C.
System: The UNT Digital Library
Squark Mixing Contributions to CP violating phase gamma (open access)

Squark Mixing Contributions to CP violating phase gamma

We investigate the possibility that the CP violation due to the soft supersymmetry breaking terms in squark mixing can give significant contributions to the various $\gamma$ related parameters in B decays, different from those of the Standard Model. We derive the new limits on $(\delta^u_12)_LL,LR,RR$ and on $(\delta^d_23)_LL,LR,RR$ from the recent data on $D^0$--$\barD^0$ oscillation as well as those on $B_s^0$--$\barB_s^0$ oscillation. We show that, together with all the other constraints, the currents limits on these parameters still allow large contributions to the CP violating phases in $B_s^0$--$\bar{B_s}^0$ as well as $D^0$--$\barD^0$ oscillations which will modify some of the proposed measurements of $\gamma$ parameters in CP violating B decays. However, the current constraints already dictate that the one-loop squark mixing contributions to various B decay amplitudes cannot be competitive with that of the Standard Model (SM), at least for those B decay modes which are dominated the tree level amplitudes within the SM, and therefore they are not significant in contributing to CP asymmetries in the corresponding B decays.
Date: September 17, 2001
Creator: Chang, Darwin; Chang, We-Fu; Keung, Wai-Yee; Sinha, Nita & Sinha, Rahul
System: The UNT Digital Library
Development and New Directions for the RELAP5-3D Graphical Users Interface (open access)

Development and New Directions for the RELAP5-3D Graphical Users Interface

The direction of development for the RELAP5 Graphical User Interfaces (RGUI) has been extended. In addition to existing plans for displaying all aspects of RELAP5 calculations, the plan now includes plans to display the calculations of a variety of codes including SCDAP, RETRAN and FLUENT. Recent work has included such extensions along with the previously planned and user-requested improvements and extensions. Visualization of heat-structures has been added. Adaptations were made for another computer program, SCDAP-3D, including plant core views. An input model builder for generating RELAP5-3D input files was partially implemented. All these are reported. Plans for future work are also summarized. These include an input processor that transfers steady-state conditions into an input file.
Date: September 1, 2001
Creator: Mesina, George Lee
System: The UNT Digital Library
THE MARS HOPPER: AN IMPULSE DRIVEN, LONG RANGE, LONG-LIVED MOBILE PLATFORM UTILIZING IN-SITU MARTIAN RESOURCES (open access)

THE MARS HOPPER: AN IMPULSE DRIVEN, LONG RANGE, LONG-LIVED MOBILE PLATFORM UTILIZING IN-SITU MARTIAN RESOURCES

The requirements for performance by planetary exploration missions are increasing. Landing at a single location to take data is no longer sufficient. Due to the increasing cost, the missions that provide mobile platforms that can acquire data at displaced locations are becoming more attractive. Landers have also had limited range due to power limitations, limited lifetime of subsystems and the inability to negotiate rough terrain. The Center for Space Nuclear Research has designed an instrumented platform that can acquire detailed data at hundreds of locations during its lifetime - a Mars Hopper. The Mars Hopper concept utilizes energy from radioisotopic decay in a manner different from any existing radioisotopic power sources—as a thermal capacitor. By accumulating the heat from radioisotopic decay for long periods, the power of the source can be dramatically increased for short periods. Thus, a radioisotopic thermal rocket (RTR) is possible. The platform will be able to “hop” from one location to the next every 5-7 days with a separation of 5-10 km per hop. Each platform will weigh around 50 kgs unfueled which is the condition at deployment. Consequently, several platforms may be deployed on a single launch from Earth. With a lifetime estimated at 5-7 …
Date: September 1, 2001
Creator: O'Brien, Robert C.; McKay, Mark; Gross, Brian & Webb, JOnathan
System: The UNT Digital Library
RELAP5-3D User Problems (open access)

RELAP5-3D User Problems

The Reactor Excursion and Leak Analysis Program with 3D capability1 (RELAP5-3D) is a reactor system analysis code that has been developed at the Idaho National Engineering and Environmental Laboratory (INEEL) for the U. S. Department of Energy (DOE). The 3D capability in RELAP5-3D includes 3D hydrodynamics2 and 3D neutron kinetics3,4. Assessment, verification, and validation of the 3D capability in RELAP5-3D is discussed in the literature5,6,7,8,9. Additional assessment, verification, and validation of the 3D capability of RELAP5-3D will be presented in other papers in this users seminar. As with any software, user problems occur. User problems usually fall into the categories of input processing failure, code execution failure, restart/renodalization failure, unphysical result, and installation. This presentation will discuss some of the more generic user problems that have been reported on RELAP5-3D as well as their resolution.
Date: September 1, 2001
Creator: Riemke, Richard Allan
System: The UNT Digital Library
Defining Science and Technology (S&T) Needs for Long-Term Stewardship of U.S. Department of Energy Sites and Development of an S&T Plan (open access)

Defining Science and Technology (S&T) Needs for Long-Term Stewardship of U.S. Department of Energy Sites and Development of an S&T Plan

A definition of Long-Term Stewardship (LTS) is: "all activities required to protect human health and the environment from hazards remaining after cleanup is complete". "Cleanup" in this sense may mean completion of a prescribed remedy for contaminated soil or buried waste, or it could mean entombment of a nuclear facility or placing nuclear materials in safe, long-term storage. Among the activities included in this definition are long-term monitoring and surveillance, maintenance of engineered barriers, operation and maintenance of long-term remedies (such as groundwater pump and treat operations), institutional controls (e.g., deed restrictions, land use restrictions, permanent markers, etc.), and information management (including intergenerational transfer of data on residual hazards). The magnitude of the U.S. Department of Energy’s (DOE) LTS commitments, in terms of scope, cost, and time, is beginning to be better understood.
Date: September 1, 2001
Creator: Mayes, Roger Allen; Kostelnik, Kevin Michael; Kearns, Paul Kenneth; Nitschke, Robert Leon & Melton, William James
System: The UNT Digital Library
A Comparison of Long-Lived, Prolieration Resistant Fast Reactors (open access)

A Comparison of Long-Lived, Prolieration Resistant Fast Reactors

Nuclear power is expected to play a significant role in meeting future electricity needs, and in significantly reducing emissions compared to fossil-fueled power plants. However, the next generation of nuclear power plants will be expected to demonstrate significant advancements in economics, safety, waste disposal, and proliferation resistance. Many reactor types have been proposed for “Generation IV”, some of which have been fast reactors. The work discussed in here is part of a larger effort at the Idaho National Engineering and Environmental Laboratory (INEEL) and at the Massachusetts Institute of Technology (MIT) to investigate the suitability of lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The goal of the entire project is to identify and analyze the key technical issues in core neutronics, materials, thermal-hydraulics, fuels, and economics associated with the development of this reactor concept. The goal of the work presented in this paper is to investigate and compare a variety of possible fuel types, looking for optimum economics for an actinide burning, low cost of electricity, reactor design using sodium or lead-bismuth as the coolant.
Date: September 1, 2001
Creator: Weaver, Kevan Dean; Herring, James Stephen & Mac Donald, Philip Elsworth
System: The UNT Digital Library
Interacting Quantum Spin Chains (open access)

Interacting Quantum Spin Chains

A brief review of recent advances in neutron scattering studies of low-dimensional quantum magnets is followed by a particular example. The separation of single-particle and continuum states in the weakly-coupled S = l/2 chains system BaCu{sub 2}Si{sub 2}O{sub 7} is described in some detail.
Date: September 9, 2001
Creator: Zheludev, A.
System: The UNT Digital Library
Fuzzy systems modeling of in situ bioremediation of chlorinatedsolve n ts (open access)

Fuzzy systems modeling of in situ bioremediation of chlorinatedsolve n ts

A large-scale vadose zone-groundwater bioremediationdemonstration was conducted at the Savannah River Site (SRS) by injectingseveral types of gases (ambient air, methane, and nitrous oxide andtriethyl phosphate mixtures) through a horizontal well in the groundwaterat a 175 ft depth. Simultaneously, soil gas was extracted through aparallel horizontal well in the vadose zone at a 80 ft depth Monitoringrevealed a wide range of spatial and temporal variations ofconcentrations of VOCs, enzymes, and biomass in groundwater and vadosezone monitoring boreholes over the field site. One of the powerful modernapproaches to analyze uncertain and imprecise data chemical data is basedon the use of methods of fuzzy systems modeling. Using fuzzy modeling weanalyzed the spatio-temporal TCE and PCE concentrations and methanotrophdensities in groundwater to assess the effectiveness of differentcampaigns of air stripping and bioremediation, and to determine the fuzzyrelationship between these compounds. Our analysis revealed some detailsabout the processes involved in remediation, which were not identified inthe previous studies of the SRS demonstration. We also identified somefuture directions for using fuzzy systems modeling, such as theevaluation of the mass balance of the vadose zone - groundwater system,and the development of fuzzy-ruled methods for optimization of managingremediation activities, predictions, and risk assessment.
Date: September 5, 2001
Creator: Faybishenko, Boris & Hazen, Terry C.
System: The UNT Digital Library
A Comparison of Long-Lived, Proliferation Resistant Fast Reactors (open access)

A Comparison of Long-Lived, Proliferation Resistant Fast Reactors

Various methods have been proposed to transmute and thus consume the current inventory of trans-uranic waste that exists in spent light-water-reactor fuel. These methods include both critical and sub-critical systems. The neutronics of metallic and nitride fuels loaded with 20-30wt% light-water-reactor plutonium plus minor actinides for use in a lead-bismuth and sodium cooled fast reactor are discussed, with an emphasis on the fuel cycle life and isotopic content. Calculations show that core life can extend beyond 20 years, and the average actinide burn rate is similar for both the sodium and lead-bismuth cooled cases ranging from 0.5 to 0.9 g/MWd.
Date: September 1, 2001
Creator: Weaver, Kevan Dean; Herring, James Stephen & Mac Donald, Philip Elsworth
System: The UNT Digital Library
Monitoring Moisture Content in Surface Barriers Using a Passive Sensor Platform (open access)

Monitoring Moisture Content in Surface Barriers Using a Passive Sensor Platform

Work is being performed to develop a versatile micro-power sensor platform for the purpose of periodic, remote sensing of environmental variables such as subsurface moisture or radiation. The key characteristics of the platform architecture are that the components are passive, thereby requiring no internal power source and that it communicates with a "reader" via short range telemetry, i.e. no wires need penetrate barrier structure. Other significant attributes include the potential for a long service life and a compact size that makes it well suited for retrofitting existing barrier structures. Functionally, the sensor package is read by a short range induction coil that both activates/powers the sensor platform and detects the sensor output via a radio frequency signal generated by the onboard programmable interface controller microchip. To date, a prototype of the platform has been constructed and tested with a commercial moisture sensor. Work is now in progress to extend the capabilities of the existing platform to permit moisture sensing through landfill surface barriers (caps). Specifically, work is being performed to extend the telemetry range for transmission through a cap, select/develop low power sensor elements, and package the components to survive subsurface conditions. Considerations are being given to minimize package dimensions …
Date: September 1, 2001
Creator: Kunerth, Dennis Clyde; Svoboda, John Mark & Lee, James Edwin
System: The UNT Digital Library
Methane Hydrates: Major Energy Source for the Future or Wishful Thinking? (open access)

Methane Hydrates: Major Energy Source for the Future or Wishful Thinking?

Methane hydrates are methane bearing, ice-like materials that occur in abundance in permafrost areas such as on the North Slope of Alaska and Canada and as well as in offshore continental margin environments throughout the world including the Gulf of Mexico and the East and West Coasts of the United States. Methane hydrate accumulations in the United States are currently estimated to be about 200,000 Tcf, which is enormous when compared to the conventional recoverable resource estimate of 2300 Tcf. On a worldwide basis, the estimate is 700,000 Tcf or about two times the total carbon in coal, oil and conventional gas in the world. The enormous size of this resource, if producible to any degree, has significant implications for U.S. and worldwide clean energy supplies and global environmental issues. Historically the petroleum industry's interests in methane hydrates have primarily been related to safety issues such as wellbore stability while drilling, seafloor stability, platform subsidence, and pipeline plugging. Many questions remain to be answered to determine if any of this potential energy resource is technically and economically viable to produce. Major technical hurdles include: 1) methods to find, characterize, and evaluate the resource; 2) technology to safely and economically produce …
Date: September 1, 2001
Creator: Thomas, Charles Phillip
System: The UNT Digital Library
A complete analytic inversion of supernova lines in the Sobolevapproximation (open access)

A complete analytic inversion of supernova lines in the Sobolevapproximation

We show that the shape of P-Cygni line profiles of photospheric phase supernova can be analytically inverted to extract both the optical depth and source function of the line -- i.e. all the physical content of the model for the case when the Sobolev approximation is valid. Under various simplifying assumptions, we derive formulae that give S(r) and {tau}(r) in terms of derivatives of the line flux with respect to wavelength. The transition region between the minimum and maximum of the line profile turns out to give especially interesting information on the optical depth near the photosphere. The formulae give insights into the relationship between line shape and physical quantities that may be useful in interpreting observed spectra and detailed numerical calculations.
Date: September 27, 2001
Creator: Kasen, Daniel; Branch, David; Baron, E. & Jeffery, David
System: The UNT Digital Library