Molecular Comb Development (open access)

Molecular Comb Development

This CRADA was developed to enable ORNL to assist Protein Discovery, Inc. to develop a novel biomolecular separation system based on an ORNL patent application 'Photoelectrochemical Molecular Comb' by Thundat, Ferrell, and Brown. The Molecular Comb concept is based on creating light-induced charge carriers at a semiconductor-liquid interface, which is kept at a potential control such that a depletion layer is formed in the semiconductor. Focusing light from a low-power illumination source creates electron-hole pairs, which get separated in the depletion layer. The light-induced charge carriers reaching the surface attract oppositely charged biomolecules present in the solution. The solution is a buffer solution with very small concentrations of biomolecules. As the focused light is moved across the surface of the semiconductor-liquid interface, the accumulated biomolecules follow the light beam. A thin layer of gel or other similar material on the surface of the semiconductor can act as a sieving medium for separating the biomolecules according to their sizes.
Date: July 17, 2007
Creator: Ferrell, T. L.; Thundat, G. T. & Witkowski, C. E., III
Object Type: Report
System: The UNT Digital Library
The Treatment of Renewable Energy Certificates, EmissionsAllowances, and Green Power Programs in State Renewables PortfolioStandards (open access)

The Treatment of Renewable Energy Certificates, EmissionsAllowances, and Green Power Programs in State Renewables PortfolioStandards

Twenty-one states and the District of Columbia have adopted mandatory renewables portfolio standards (RPS) over the last ten years. Renewable energy attributes-such as the energy source, conversion technology, plant location and vintage, and emissions-are usually required to verify compliance with these policies, sometimes through attributes bundled with electricity, and sometimes with the attributes unbundled from electricity and traded separately as renewable energy certificates (RECs). This report summarizes the treatment of renewable energy attributes in state RPS rules. Its purpose is to provide a source of information for states considering RPS policies, and also to draw attention to certain policy issues that arise when renewable attributes and RECs are used for RPS compliance. Three specific issues are addressed: (1) the degree to which unbundled RECs are allowed under existing state RPS programs and the status of systems to track RECs and renewable energy attributes; (2) definitions of the renewable energy attributes that must be included in order to meet state RPS obligations, including the treatment of available emissions allowances; and (3) state policies on whether renewable energy or RECs sold through voluntary green power transactions may count towards RPS obligations.
Date: April 17, 2007
Creator: Holt, Edward A. & Wiser, Ryan H.
Object Type: Report
System: The UNT Digital Library
Surface roughness effects on the solar reflectance of cool asphalt shingles (open access)

Surface roughness effects on the solar reflectance of cool asphalt shingles

We analyze the solar reflectance of asphalt roofing shingles that are covered with pigmented mineral roofing granules. The reflecting surface is rough, with a total area approximately twice the nominal area. We introduce a simple analytical model that relates the 'micro-reflectance' of a small surface region to the 'macro-reflectance' of the shingle. This model uses a mean field approximation to account for multiple scattering effects. The model is then used to compute the reflectance of shingles with a mixture of different colored granules, when the reflectances of the corresponding mono-color shingles are known. Simple linear averaging works well, with small corrections to linear averaging derived for highly reflective materials. Reflective base granules and reflective surface coatings aid achievement of high solar reflectance. Other factors that influence the solar reflectance are the size distribution of the granules, coverage of the asphalt substrate, and orientation of the granules as affected by rollers during fabrication.
Date: February 17, 2008
Creator: Akbari, Hashem; Berdahl, Paul; Akbari, Hashem; Jacobs, Jeffry & Klink, Frank
Object Type: Article
System: The UNT Digital Library
Heavy Quarkonium Production in Single Transverse Polarized HighEnergy Scattering (open access)

Heavy Quarkonium Production in Single Transverse Polarized HighEnergy Scattering

We formulate the single transverse spin asymmetry in heavyquarkoniumproduction in lepton-nucleon and nucleon-nucleon collisionsinthe non-relativistic limit. We findthat the asymmetry is very sensitiveto the production mechanism. The finalstate interactions with the heavyquark and antiquark cancel out among themselves whenthe pair are producedin a color-single configuration, or cancel out with the initialstateinteraction in pp scattering when they are in color-octet. As aconsequence, the asymmetry is nonzero in ep collisions only in thecolor-octet model, whereas in pp collisions only in the color-singletmodel.
Date: January 17, 2008
Creator: Yuan, Feng
Object Type: Article
System: The UNT Digital Library
Ion Deflection for Final Optics In Laser Inertial Fusion Power Plants (open access)

Ion Deflection for Final Optics In Laser Inertial Fusion Power Plants

Left unprotected, both transmissive and reflective final optics in a laser inertial fusion power plant would quickly fail from melting, pulsed thermal stresses, or degradation of optical properties as a result of ion implantation. One potential option for mitigating this threat is to magnetically deflect the ions such that they are directed into a robust energy dump. In this paper we detail integrated studies that have been carried out to asses the viability of this approach for protecting final optics.
Date: November 17, 2006
Creator: Abbott, R P & Latkowski, J F
Object Type: Article
System: The UNT Digital Library
Magnetic Measurements and Simulations for a 4-magnet Dipole Chicane for the International Linear Collider (open access)

Magnetic Measurements and Simulations for a 4-magnet Dipole Chicane for the International Linear Collider

T-474 at SLAC is a prototype BPM-based energy spectrometer for the ILC. We describe magnetic measurements and simulations for the 4-magnet chicane used in T-474.
Date: December 17, 2007
Creator: Schreiber, H. J.; Viti, M.; /DESY; Duginov, V. N.; Kostromin, S. A.; Morozov, N. A. et al.
Object Type: Article
System: The UNT Digital Library
A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum (open access)

A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum

We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and Kuiper Belt strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. If detected, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic {gamma}-ray emission. Additionally, it can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions, and the mass spectrum of small bodies in the Main Belt and Kuiper Belt. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory …
Date: December 17, 2007
Creator: Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.; Michelson, Peter F. & Ormes, Jonathan F.
Object Type: Article
System: The UNT Digital Library
Exaggerated Health Benefits of Physical Fitness and Activity dueto Self-selection. (open access)

Exaggerated Health Benefits of Physical Fitness and Activity dueto Self-selection.

Background: The predicted health benefits of becomingphysically active or fit will be exaggerated if health outcomes causefitness and activity rather than the converse in prospective andcross-sectional epidemiological studies. Objective: Assess whether therelationships of adiposity to fitness and activity are explained byadiposity prior to exercising. Design: Cross-sectional study of physicalfitness (running speed during 10km foot race) and physical activity(weekly running distance) to current BMI (BMIcurrent) and BMI at thestart of running (BMIstarting) in 44,370 male and 25,252 femaleparticipants of the National Runners' Health Study. Results: BMIstartingexplained all of the association between fitness and BMIcurrent in bothsexes, but less than a third of the association between physical activityand BMIcurrent in men. In women, BMIstarting accounted for 58 percent ofthe association between BMIcurrent and activity levels. The 95thpercentile of BMIcurrent showed substantially greater declines withfitness and activity levels than the 5th percentile of BMIcurrent in men(i.e., the negative slope for 95th percentile was 2.6-fold greater thanthe 5th percentile for fitness and 3-fold greater for activity) and women(6-fold and 3.4-fold greater, respectively). At all percentiles, theregression slopes relating BMIstarting to fitness were comparable orgreater (more negative) than the slopes relating BMIcurrent to fitness,whereas the converse was true for activity. Conclusion: Self-selectionbias accounts for all …
Date: January 17, 2006
Creator: Williams, Paul T.
Object Type: Article
System: The UNT Digital Library
TRITIUM BARRIER MATERIALS AND SEPARATION SYSTEMS FOR THE NGNP (open access)

TRITIUM BARRIER MATERIALS AND SEPARATION SYSTEMS FOR THE NGNP

Contamination of downstream hydrogen production plants or other users of high-temperature heat is a concern of the Next Generation Nuclear Plant (NGNP) Project. Due to the high operating temperatures of the NGNP (850-900 C outlet temperature), tritium produced in the nuclear reactor can permeate through heat exchangers to reach the hydrogen production plant, where it can become incorporated into process chemicals or the hydrogen product. The concentration limit for tritium in the hydrogen product has not been established, but it is expected that any future limit on tritium concentration will be no higher than the air and water effluent limits established by the NRC and the EPA. A literature survey of tritium permeation barriers, capture systems, and mitigation measures is presented and technologies are identified that may reduce the movement of tritium to the downstream plant. Among tritium permeation barriers, oxide layers produced in-situ may provide the most suitable barriers, though it may be possible to use aluminized surfaces also. For tritium capture systems, the use of getters is recommended, and high-temperature hydride forming materials such as Ti, Zr, and Y are suggested. Tritium may also be converted to HTO in order to capture it on molecular sieves or getter …
Date: July 17, 2008
Creator: Sherman, S & Thad Adams, T
Object Type: Report
System: The UNT Digital Library
Particle-Size-Distribution of Nevada Test Site Soils (open access)

Particle-Size-Distribution of Nevada Test Site Soils

The amount of each size particle in a given soil is called the particle-size distribution (PSD), and the way it feels to the touch is called the soil texture. Sand, silt, and clay are the three particle sizes of mineral material found in soils. Sand is the largest sized particle and it feels gritty; silt is medium sized and it feels floury; and clay is the smallest and if feels sticky. Knowing the particle-size distribution of a soil sample helps to understand many soil properties such as how much water, heat, and nutrients the soil will hold, how fast water and heat will move through the soil, and what kind of structure, bulk density and consistence the soil will have. Furthermore, the native particle-size distribution of the soil in the vicinity of ground zero of a nuclear detonation plays a major role in nuclear fallout. For soils that have a high-sand content, the near-range fallout will be relatively high and the far-range fallout will be relatively light. Whereas, for soils that have a high-silt and high-clay content, the near-range fallout will be significantly lower and the far-range fallout will be significantly higher. As part of a program funded by the …
Date: September 17, 2007
Creator: Spriggs, G & Ray-Maitra, A
Object Type: Report
System: The UNT Digital Library
Summary of Stimulated Raman Scattering Experiments in the Nova Air-Path and Projected Nova and Nova II System Performance Limits (open access)

Summary of Stimulated Raman Scattering Experiments in the Nova Air-Path and Projected Nova and Nova II System Performance Limits

The authors present the results of high intensity beam propagation experiments conducted with the Nova laser system to investigate the occurrence of stimulated rotational Raman scattering (SRRS) from atmospheric nitrogen in the beam path. Enclosed is a preprint entitled ''Stimulated Rotational Raman Scattering in Nitrogen in Long Air Paths'' that they have published in the November issue of Optics Letters. The physics issues associated with SRRS are discussed at length in the preprint. The small signal steady-state SRRS gain coefficient that they determined from threshold measurements is in excellent agreement with recent direct SRRS gain measurements by Bischel, et al., at SRI, and is in good agreement with early gain estimates from Averbakh, et al., in the Soviet Union. Consequently, they have a high degree of confidence in the gain coefficient. In addition, threshold SRRS experiments on the long air-path Nova II system are in substantial agreement with the earlier Nova experiments. Nova and Nova II system performance limitations were not critically addressed in the publication so they shall discuss these issues in this paper.
Date: July 17, 2007
Creator: Henesian, M.; Swift, C. D. & Murray, J. R.
Object Type: Report
System: The UNT Digital Library
The Shewanella oneidensis MR-1 Fluxome under Various OxygenConditions (open access)

The Shewanella oneidensis MR-1 Fluxome under Various OxygenConditions

The central metabolic fluxes of Shewanella oneidensis MR-1were examined under carbon-limited (aerobic) and oxygen-limited(micro-aerobic) chemostat conditions using 13C labeled lactate as thesole carbon source. The carbon labeling patterns of key amino acids inbiomass were probed using both GC-MS and 13C-NMR. Based on the genomeannotation, a metabolic pathway model was constructed to quantify thecentral metabolic flux distributions. The model showed that thetricarboxylic acid (TCA) cycle is the major carbon metabolism route underboth conditions. The Entner-Doudoroff and pentose phosphate pathways weremainly utilized for biomass synthesis (flux below 5 percent of thelactate uptake rate). The anapleurotic reactions (pyruvate to malate andoxaloacetate to phosphoenolpyruvate) and the glyoxylate shunt wereactive. Under carbon-limited conditions, a substantial amount of carbonwas oxidized via the highly reversible serine metabolic pathway. Fluxesthrough the TCA cycle were less whereas acetate production was more underoxygen limitation than under carbon limitation. Although fluxdistributions under aerobic, micro-aerobic, and shake-flask cultureconditions were dramatically different, the relative flux ratios of thecentral metabolic reactions did not vary significantly. Hence, S.oneidensis metabolism appears to be quite robust to environmentalchanges. Our study also demonstrates the merit of coupling GC-MS with 13CNMR for metabolic flux analysis to reduce the use of 13C labeledsubstrates and to obtain more accurate flux values.
Date: March 17, 2006
Creator: Tang, Yinjie J.; Hwang, Judy S.; Wemmer, David E. & Keasling, Jay D.
Object Type: Article
System: The UNT Digital Library
Ferromagnetism in tetragonally distorted LaCoO3 thin films (open access)

Ferromagnetism in tetragonally distorted LaCoO3 thin films

Thin films of epitaxial LaCoO{sub 3} were synthesized on SrTiO{sub 3} and (La, Sr)(Al, Ta)O{sub 3} substrates varying the oxygen background pressure in order to evaluate the impact of epitaxial growth as well as oxygen vacancies on the long range magnetic order. The epitaxial constraints from the substrate impose a tetragonal distortion compared to the bulk form. X-ray absorption and x-ray magnetic circular dichroism measurements confirmed that the ferromagnetism arises from the Co ions and persists through the entire thickness of the film. It was found that for the thin films to show ferromagnetic order they have to be grown under the higher oxygen pressures, since a decrease in oxygen deposition pressure alters the film structure and suppresses ferromagnetism in the LaCoO{sub 3} films. A correlation of the structure and magnetism suggests that the tetragonal distortions induce the ferromagnetism.
Date: September 17, 2008
Creator: Mehta, Virat Vasav; Liberati, Marco; Wong, Franklin J.; Chopdekar, Rajesh Vilas; Arenholz, Elke & Suzuki, Yuri
Object Type: Article
System: The UNT Digital Library
Beam Dynamics Studies for the SPARC Project (open access)

Beam Dynamics Studies for the SPARC Project

The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities.
Date: March 17, 2008
Creator: Ferrario, M.; Biagini, Maria E.; Boscolo, M.; Fusco, V.; Guiducci, S.; Migliorati, M. et al.
Object Type: Article
System: The UNT Digital Library
BIOGEOCHEMICAL GRADIENTS AS A FRAMEWORK FOR UNDERSTANDING WASTE SITE EVOLUTION (open access)

BIOGEOCHEMICAL GRADIENTS AS A FRAMEWORK FOR UNDERSTANDING WASTE SITE EVOLUTION

The migration of biogeochemical gradients is a useful framework for understanding the evolution of biogeochemical conditions in groundwater at waste sites contaminated with metals and radionuclides. This understanding is critical to selecting sustainable remedies and evaluating sites for monitored natural attenuation, because most attenuation mechanisms are sensitive to geochemical conditions such as pH and redox potential. Knowledge of how gradients in these parameters evolve provides insights into the behavior of contaminants with time and guides characterization, remedy selection, and monitoring efforts. An example is a seepage basin site at the Savannah River Site in South Carolina where low-level acidic waste has seeped into groundwater. The remediation of this site relies, in part, on restoring the natural pH of the aquifer by injecting alkaline solutions. The remediation will continue until the pH up-flow of the treatment zone increases to an acceptable value. The time required to achieve this objective depends on the time it takes the trailing pH gradient, the gradient separating the plume from influxing natural groundwater, to reach the treatment zone. Predictions of this length of time will strongly influence long-term remedial decisions.
Date: October 17, 2008
Creator: Denham, M. & Karen Vangelas, K.
Object Type: Article
System: The UNT Digital Library
A stable finite difference method for the elastic wave equation on complex geometries with free surfaces (open access)

A stable finite difference method for the elastic wave equation on complex geometries with free surfaces

The isotropic elastic wave equation governs the propagation of seismic waves caused by earthquakes and other seismic events. It also governs the propagation of waves in solid material structures and devices, such as gas pipes, wave guides, railroad rails and disc brakes. In the vast majority of wave propagation problems arising in seismology and solid mechanics there are free surfaces. These free surfaces have, in general, complicated shapes and are rarely flat. Another feature, characterizing problems arising in these areas, is the strong heterogeneity of the media, in which the problems are posed. For example, on the characteristic length scales of seismological problems, the geological structures of the earth can be considered piecewise constant, leading to models where the values of the elastic properties are also piecewise constant. Large spatial contrasts are also found in solid mechanics devices composed of different materials welded together. The presence of curved free surfaces, together with the typical strong material heterogeneity, makes the design of stable, efficient and accurate numerical methods for the elastic wave equation challenging. Today, many different classes of numerical methods are used for the simulation of elastic waves. Early on, most of the methods were based on finite difference approximations …
Date: December 17, 2007
Creator: Appelo, D & Petersson, N A
Object Type: Article
System: The UNT Digital Library
ILC Positron Source Target Update (open access)

ILC Positron Source Target Update

None
Date: September 17, 2007
Creator: Piggott, W T; Gronberg, J; Hagler, L; Sunwoo, A & Darnell, I
Object Type: Report
System: The UNT Digital Library
Cummins Power Generation SECA Phase 1 (open access)

Cummins Power Generation SECA Phase 1

The following report documents the progress of the Cummins Power Generation (CPG) SECA Phase 1 SOFC development and final testing under the U.S. Department of Energy Solid State Energy Conversion Alliance (SECA) contract DE-FC26-01NT41244. This report overviews and summarizes CPG and partner research development leading to successful demonstration of the SECA Phase 1 objectives and significant progress towards SOFC commercialization. Significant Phase 1 Milestones: (1) Demonstrated: (a) Operation meeting Phase 1 requirements on commercial natural gas. (b) LPG and Natural Gas CPOX fuel reformers. (c) SOFC systems on dry CPOX reformate. (c) Steam reformed Natural Gas operation. (d) Successful start-up and shut-down of SOFC system without inert gas purge. (e) Utility of stack simulators as a tool for developing balance of plant systems. (2) Developed: (a) Low cost balance of plant concepts and compatible systems designs. (b) Identified low cost, high volume components for balance of plant systems. (c) Demonstrated high efficiency SOFC output power conditioning. (d) Demonstrated SOFC control strategies and tuning methods. The Phase 1 performance test was carried out at the Cummins Power Generation facility in Minneapolis, Minnesota starting on October 2, 2006. Performance testing was successfully completed on January 4, 2007 including the necessary steady-state, transient, …
Date: August 17, 2007
Creator: Vesely, Charles
Object Type: Report
System: The UNT Digital Library
Criteria for Determination of MC&A System Effectiveness (open access)

Criteria for Determination of MC&A System Effectiveness

The Nevada Test Site (NTS) is a test bed for implementation of the Safeguards First Principles Initiative (SFPI), a risk-based approach to Material Control & Accountability (MC&A) requirements. The Comprehensive Assessment of Safeguards Strategies (COMPASS) model is used to determine the effectiveness of safeguards systems under SFPI. Under this model, MC&A is divided into nine primary elements. Each element is divided into sub-elements. Then, each sub-element is assigned two values, effectiveness and contribution, that are used to calculate the rating. Effectiveness is a measure of sub-element implementation and how well it meets requirements. Contribution is a relative measure of the importance, and functions as a weighting factor. The COMPASS model provides the methodology for calculation of element and subelement, but not the actual criteria. Each site must develop its own criteria. For the rating to be meaningful, the effectiveness criteria must be objective and based on explicit, measurable criteria. Contribution (weights) must reflect the importance within the MC&A program. This paper details the NTS approach to system effectiveness and contribution values, and will cover the following: the basis for the ratings, an explanation of the contribution weights, and the objective, performance-based effectiveness criteria. Finally, the evaluation process will be described.
Date: July 17, 2008
Creator: Geneva Johnson, DeAnn Long, Ross Albright, John Wright
Object Type: Article
System: The UNT Digital Library
High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays (open access)

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.
Date: April 17, 2007
Creator: Jovanovic, I; Shverdin, M; Gibson, D & Brown, C
Object Type: Article
System: The UNT Digital Library
Exceptional Ground Accelerations and Velocities Caused by Earthquakes (open access)

Exceptional Ground Accelerations and Velocities Caused by Earthquakes

This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.
Date: January 17, 2008
Creator: Anderson, John
Object Type: Report
System: The UNT Digital Library
Longitudinal Density Modulation and Energy Conversion in Intense Beams (open access)

Longitudinal Density Modulation and Energy Conversion in Intense Beams

Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may under some circumstances be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams, and discusses three recent experiments related to the dynamics of density-modulated electron beams.
Date: February 17, 2006
Creator: Harris, J; Neumann, J; Tian, K & O'Shea, P
Object Type: Article
System: The UNT Digital Library
Enchanced hohlraum radiation drive through reduction of wall losses with high-Z mixture "cocktail" wall materials (open access)

Enchanced hohlraum radiation drive through reduction of wall losses with high-Z mixture "cocktail" wall materials

We present results from experiments, numerical simulations and analytic modeling, demonstrating enhanced hohlraum performance. Care in the fabrication and handling of hohlraums with walls consisting of high-Z mixtures (cocktails) has led to our demonstration, for the first time, of a significant increase in radiation temperature (up to +7eV at 300 eV) compared to a pure Au hohlraum, in agreement with predictions and ascribable to reduced wall losses. The data extrapolated to full NIF suggest we can expect an 18% reduction in wall loss for the current ignition design by switching to cocktail hohlraums, consistent with requirements for ignition with 1MJ laser energy.
Date: May 17, 2006
Creator: Schein, J; Jones, O; Rosen, M; Dewald, E; Glenzer, S; Gunther, J et al.
Object Type: Article
System: The UNT Digital Library