The National Ignition Facility and the Promise of Inertial Fusion Energy (open access)

The National Ignition Facility and the Promise of Inertial Fusion Energy

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is now operational. The NIF is the world's most energetic laser system capable of producing 1.8 MJ and 500 TW of ultraviolet light. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in planetary interiors and stellar environments. On September 29, 2010, the first integrated ignition experiment was conducted, demonstrating the successful coordination of the laser, cryogenic target system, array of diagnostics and infrastructure required for ignition demonstration. In light of this strong progress, the U.S. and international communities are examining the implication of NIF ignition for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a laser with 10% electrical-optical efficiency, as well as further development and advances in large-scale target fabrication, target injection, and other supporting technologies. These capabilities could lead to a prototype IFE demonstration plant in the 10- to 15-year time frame. …
Date: December 13, 2010
Creator: Moses, E I
Object Type: Article
System: The UNT Digital Library
kt-factorization for Hard Processes in Nuclei (open access)

kt-factorization for Hard Processes in Nuclei

Two widely proposed kt-dependent gluon distributions in the small-x saturation regime are investigated using two particle back-to-back correlations in high energy scattering processes. The Weizsacker-Williams gluon distribution, interpreted as the number density of gluon inside the nucleus, is studied in the quark-antiquark jet correlation in deep inelastic scattering. On the other hand, the unintegrated gluon distribution, defined as the Fourier transform of the color-dipole cross section, is probed in the direct photon-jet correlation in pA collisions. Dijet-correlation in pA collisions depends on both gluon distributions through combination and convolution in the large Nc limit. We calculate these processes in two approaches: the transverse momentum dependent factorization approach and the color-dipole/color glass condensate formalism, and they agree with each other completely.
Date: September 13, 2010
Creator: Dominguez, Fabio; Xiao, Bo-Wen & Yuan, Feng
Object Type: Article
System: The UNT Digital Library
2010 Water & Aqueous Solutions (open access)

2010 Water & Aqueous Solutions

Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).
Date: August 13, 2010
Creator: Ben-Amotz, Dor
Object Type: Article
System: The UNT Digital Library
Direct Comparison of Brookhaven Reflectivity Measurements with Free-Electron Theory (open access)

Direct Comparison of Brookhaven Reflectivity Measurements with Free-Electron Theory

The reflectivity at normal incidence of copper and aluminum samples was recently measured over a large frequency range at Brookhaven by one of us (JT). Then using the Kramers-Kroning integrals, and assuming the free-electron model of conductivity, the dependence of conductivity on frequency was obtained. The results seemed to suggest, for example, that the dc conductivities of the copper and evaporated aluminum samples are a factor of 3 lower than expected. We propose in this report, instead, directly fitting the free-electron model to the low frequency end of the reflectivity data. This fitting does not depend on the higher frequency results and on Kramers-Kronig integrations, but it does assume that the data at the low frequency end is sufficiently accurate. Note that for our LCLS wakefield studies, it is only over these (relatively) low frequencies that we need to know the electrical properties of the metals. The equations that relate reflectivity R with the free electron parameters dc conductivity {sigma} and relaxation time {tau} are: (1) {tilde {sigma}} = {sigma}/1-ikc{tau}; (2) {tilde n} = {radical} {tilde {epsilon}} = {radical}(1+4{pi}i{tilde k}c/{omega}); and (3) R = |{tilde n}-1/{tilde n} + 1|{sup 2}. The parameters are ac conductivity {tilde {sigma}}, index of refraction …
Date: December 13, 2010
Creator: Bane, Karl L.F.
Object Type: Report
System: The UNT Digital Library
LITERATURE REVIEW ON MAXIMUM LOADING OF RADIONUCLIDES ON CRYSTALLINE SILICOTITANATE (open access)

LITERATURE REVIEW ON MAXIMUM LOADING OF RADIONUCLIDES ON CRYSTALLINE SILICOTITANATE

Plans are underway to use small column ion exchange (SCIX) units installed in high-level waste tanks to remove Cs-137 from highly alkaline salt solutions at Savannah River Site. The ion exchange material slated for the SCIX project is engineered or granular crystalline silicotitanate (CST). Information on the maximum loading of radionuclides on CST is needed by Savannah River Remediation for safety evaluations. A literature review has been conducted that culminated in the estimation of the maximum loading of all but one of the radionuclides of interest (Cs-137, Sr-90, Ba-137m, Pu-238, Pu-239, Pu-240, Pu-241, Am-241, and Cm-244). No data was found for Cm-244.
Date: October 13, 2010
Creator: Adu-Wusu, K. & Pennebaker, F.
Object Type: Report
System: The UNT Digital Library
A Design Report for the Optical Transition Radiation Imager for the LCLS Undulator (open access)

A Design Report for the Optical Transition Radiation Imager for the LCLS Undulator

The Linac Coherent Light Source (LCLS), a free-electron x-ray laser, is under design and construction. Its high-intensity electron beam, 3400 A in peak current and 46 TW in peak power, is concentrated in a small area (37 micrometer in rms radius) inside its undulator. Ten optical transition radiation (OTR) imagers are planned between the undulator segments for characterizing the transverse profiles of the electron beam. In this note, we report on the optical and mechanical design of the OTR imager. Through a unique optical arrangement, using a near-normal-incidence screen and a multi-layer coated mirror, this imager will achieve a fine resolution (12 micrometer or better) over the entire field of view (8 mm x 5 mm), with a high efficiency for single-shot imaging. A digital camera will be used to read out the beam images in a programmable region (5 mm x 0.5 mm) at the full beam repetition rate (120 Hz), or over the entire field at a lower rate (10 Hz). Its built-in programmable amplifier will be used as an electronic intensity control.
Date: December 13, 2010
Creator: Yang, Bingxin
Object Type: Report
System: The UNT Digital Library
Development of a Polar Drive Shock Ignition Platform on the National Ignition Facility (open access)

Development of a Polar Drive Shock Ignition Platform on the National Ignition Facility

None
Date: May 13, 2010
Creator: Perkins, L. J.; Schurtz, G. P.; Betti, R.; Craxton, R. S.; LaFortune, K. N.; Casner, A. et al.
Object Type: Report
System: The UNT Digital Library
Effects of Electromagnetic Fields on Fish and Invertebrates (open access)

Effects of Electromagnetic Fields on Fish and Invertebrates

In this progress report, we describe the preliminary experiments conducted with three fish and one invertebrate species to determine the effects of exposure to electromagnetic fields. During fiscal year 2010, experiments were conducted with coho salmon (Onchrohychus kisutch), California halibut (Paralicthys californicus), Atlantic halibut (Hippoglossus hippoglossus), and Dungeness crab (Cancer magister). The work described supports Task 2.1.3: Effects on Aquatic Organisms, Subtask 2.1.3.1: Electromagnetic Fields.
Date: October 13, 2010
Creator: Schultz, Irvin R.; Woodruff, Dana L.; Marshall, Kathryn E.; Pratt, William J. & Roesijadi, Guritno
Object Type: Report
System: The UNT Digital Library
Safeguard By Design Lessons Learned from DOE Experience Integrating Safety into Design (open access)

Safeguard By Design Lessons Learned from DOE Experience Integrating Safety into Design

This paper identifies the lessons to be learned for the institutionalization of Safeguards by Design (SBD) from the Department of Energy (DOE) experience developing and implementing DOE-STD-1189-2008, Integration of Safety into the Design Process. The experience is valuable because of the similarity of the challenges of integrating safety and safeguards into the design process. The paper reviews the content and development of DOE-STD-1189-2008 from its initial concept in January 2006 to its issuance in March 2008. Lessons learned are identified in the areas of the development and structure of requirements for the SBD process; the target audience for SBD requirements and guidance, the need for a graded approach to SBD, and a possible strategy for development and implementation of SBD within DOE.
Date: April 13, 2010
Creator: Hockert, John & Burbank, Roberta L.
Object Type: Report
System: The UNT Digital Library
A Vibrating Wire System For Quadrupole Fiducialization (open access)

A Vibrating Wire System For Quadrupole Fiducialization

A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization step of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire …
Date: December 13, 2010
Creator: Wolf, Zachary
Object Type: Report
System: The UNT Digital Library
The Status of De-Inventory of Security Category I/II Nuclear Materials at Lawrence Livermore National Laboratory (LLNL) (open access)

The Status of De-Inventory of Security Category I/II Nuclear Materials at Lawrence Livermore National Laboratory (LLNL)

None
Date: May 13, 2010
Creator: Riley, D C & Dodson, K
Object Type: Article
System: The UNT Digital Library
Efficiency Improvement of Nitride-Based Solid State Light Emitting Materials -- CRADA Final Report (open access)

Efficiency Improvement of Nitride-Based Solid State Light Emitting Materials -- CRADA Final Report

The development of In{sub x}Ga{sub 1-x} N/GaN thin film growth by Molecular Beam Epitaxy has opened a new route towards energy efficient solid-state lighting. Blue and green LED's became available that can be used to match the whole color spectrum of visible light with the potential to match the eye response curve. Moreover, the efficiency of such devices largely exceeds that of incandescent light sources (tungsten filaments) and even competes favorably with lighting by fluorescent lamps. It is, however, also seen in Figure 1 that it is essential to improve on the luminous performance of green LED's in order to mimic the eye response curve. This lack of sufficiently efficient green LED's relates to particularities of the In{sub x}Ga{sub 1-x}N materials system. This ternary alloy system is polar and large strain is generated during a lattice mismatched thin film growth because of the significantly different lattice parameters between GaN and InN and common substrates such as sapphire. Moreover, it is challenging to incorporate indium into GaN at typical growth temperatures because a miscibility gap exists that can be modified by strain effects. As a result a large parameter space needs exploration to optimize the growth of In{sub x}Ga{sub 1-x}N and …
Date: May 13, 2010
Creator: Kisielowski, Christian & Weber, Eicke
Object Type: Report
System: The UNT Digital Library
Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms: Final Report (open access)

Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms: Final Report

Final Report for “Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms”
Date: December 13, 2010
Creator: Olszyk, David M.
Object Type: Report
System: The UNT Digital Library
Realizing novel accelerator concepts in an X-band photo-injector (open access)

Realizing novel accelerator concepts in an X-band photo-injector

In this project we propose to investigate the use of novel accelerator structure cell geometry to enhance the performance of X-band photo-injectors. Making novel accelerator concepts possible involves fabrication and testing of components to ensure that the performance predicted by simulation is robustly achievable. This work is important because photo-injectors are increasingly used to provide high brightness electron beams for light sources, pushing their performance to the limits, but also requiring them to be user-facility stable. Careful investigation in both computer simulation and design, and low power testing of piece parts will enable the successful fabrication of an advanced X-band photo-injector.
Date: April 13, 2010
Creator: Marsh, R
Object Type: Report
System: The UNT Digital Library
Triggering for Magnetic Field Measurements of the LCLS Undulators (open access)

Triggering for Magnetic Field Measurements of the LCLS Undulators

A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.
Date: December 13, 2010
Creator: Hacker, Kirsten
Object Type: Report
System: The UNT Digital Library
MIDAS (Material Implementation, Database, and Analysis Source): A comprehensive resource of material properties (open access)

MIDAS (Material Implementation, Database, and Analysis Source): A comprehensive resource of material properties

MIDAS is aimed to be an easy-to-use and comprehensive common source for material properties including both experimental data and models and their parameters. At LLNL, we will develop MIDAS to be the central repository for material strength related data and models with the long-term goal to encompass other material properties. MIDAS will allow the users to upload experimental data and updated models, to view and read materials data and references, to manipulate models and their parameters, and to serve as the central location for the application codes to access the continuously growing model source codes. MIDAS contains a suite of interoperable tools and utilizes components already existing at LLNL: MSD (material strength database), MatProp (database of materials properties files), and MSlib (library of material model source codes). MIDAS requires significant development of the computer science framework for the interfaces between different components. We present the current status of MIDAS and its future development in this paper.
Date: December 13, 2010
Creator: Tang, M.; Norquist, P.; Barton, N.; Durrenberger, K.; Florando, J. & Attia, A.
Object Type: Article
System: The UNT Digital Library
Evolution of Static Physical Properties in Plutonium by Self-irradiation Damage (open access)

Evolution of Static Physical Properties in Plutonium by Self-irradiation Damage

The alpha-decay of plutonium leads to the age-related change in physical properties. This paper presents updated results of age-related effects on enriched and reference alloys measured from immersion density, dilatometry, and mechanical tests. After nearly 100 equivalent years of aging, both the immersion density and dilatometry show that the enriched alloys are decreasing in density by less than 0.02% per year and now exhibit a near linear density decrease, without void swelling. The tensile tests show that the aging process increases the strength of plutonium alloys, followed by possible saturation past 70 equivalent years of age. The ultimate goal of this work is to develop capabilities to predict physical properties changed by aging effects.
Date: April 13, 2010
Creator: Chung, B W; Lema, K E & Hiromoto, D S
Object Type: Article
System: The UNT Digital Library
ROCK DEFORMATION 2010 GORDON RESEARCH CONFERENCE, AUGUST 8-13, 2010 (open access)

ROCK DEFORMATION 2010 GORDON RESEARCH CONFERENCE, AUGUST 8-13, 2010

Creep in the crust and mantle is commonly considered a steady-state process. This view prevails despite the fact that earthquakes do not represent steady-state and at the base of the seismogenic zone, for example, the stresses that drive creep must vary with the earthquake cycle. The contribution of transient versus steady-state behavior is not easy to determine from naturally-deformed brittle or plastic rocks and our view of steady-state depends on whether we consider geological or shorter time-scales. Perhaps we avoid a non steady-state picture because we lack appropriate descriptive or quantitative tools. The aim of the 2010 Gordon Research Conference (GRC) in rock deformation is to explore what we know about non steady-state deformation and how we might advance our understanding through geological and geophysical field investigations, laboratory experiments and modeling. This will require an appraisal of the applicability of steady-state concepts as well as an exploration of transient behavior, in which processes and physical properties cycle between different states as might be the case during earthquake cycles, and transitions in behavior, where finite strain or changing environmental conditions lead to changes in processes and properties. Conference sessions will cover seven broad and interlinked topics. (1) What is steady state?; …
Date: August 13, 2010
Creator: Prior, David
Object Type: Article
System: The UNT Digital Library
Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation (open access)

Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with …
Date: May 13, 2010
Creator: Colby, Denise; Bergman, Robert & Ellman, Jonathan
Object Type: Article
System: The UNT Digital Library
Location of Maximum Credible Beam Losses in LCLS Injector (open access)

Location of Maximum Credible Beam Losses in LCLS Injector

The memo describes the maximum credible beam the LCLS injector can produce and lose at various locations along the beamline. The estimation procedure is based upon three previous reports [1, 2, 3]. While specific numbers have been updated to accurately reflect the present design parameters, the conclusions are very similar to those given in Ref 1. The source of the maximum credible beam results from the explosive electron emission from the photocathode if the drive laser intensity exceeds the threshold for plasma production. In this event, the gun's RF field can extract a large number of electrons from this plasma which are accelerated out of the gun and into the beamline. This electron emission persists until it has depleted the gun of all its energy. Hence the number of electrons emitted per pulse is limited by the amount of stored RF energy in the gun. It needs to be emphasized that this type of emission is highly undesirable, as it causes permanent damage to the cathode.
Date: December 13, 2010
Creator: Mao, Stan
Object Type: Report
System: The UNT Digital Library
Potentially Missing Physics of the Early Universe: Nonlinear Vacuum Polarization in Intense Blackbody Radiation (open access)

Potentially Missing Physics of the Early Universe: Nonlinear Vacuum Polarization in Intense Blackbody Radiation

The standard Big Bang universe model is mainly based on linear interactions, except during exotic periods such as inflation. The purpose of the present proposal is to explore the effects, if any, of vacuum polarization in the very high energy density environment of the early universe. These conditions can be found today in astrophysical settings and may also be emulated in the laboratory using high intensity advanced lasers. Shortly after the Big Bang, there once existed a time when the energy density of the universe corresponded to a temperature in the range 10{sup 8} - 10{sup 9} K, sufficient to cause vacuum polarization effects. During this period, the nonlinear vacuum polarization may have had significant modifications on the propagation of radiation. Thus the thermal spectrum of the early universe may have been starkly non-Planckian. Measurements of the cosmic microwave background today show a spectrum relatively close to an ideal blackbody. Could the early universe have shown spectral deviations due to nonlinear vacuum effects? If so, is it possible to detect traces of those relic photons in the universe today? Found in galactic environments, compact objects such as blazars and magnetars can possess astronomically large energy densities that far exceed anything …
Date: April 13, 2010
Creator: Wu, S Q & Hartemann, F V
Object Type: Report
System: The UNT Digital Library
Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents (open access)

Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents

We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields produced with orthogonal and unipolar Gaussian-pulse currents. The optimal width of the orthogonal pulses and their time delay are found, from analytical and micromagnetic numerical calculations, to be determined only by the angular eigenfrequency {omega}{sub D} for a given vortex-state disk of polarization p, such that {sigma}=1/{omega}{sub D} and {Delta}t={pi}/2 p/{omega}{sub D} . The estimated optimal pulse parameters are in good agreement with the experimental results. This work lays a foundation for energy-efficient information recording in vortex-core cross-point architecture.
Date: October 13, 2010
Creator: Jung, H.; Choi, Y. S.; Yoo, M. W.; Im, M. Y. & Kim, S. K.
Object Type: Article
System: The UNT Digital Library
Discharge Physics of High Power Impulse Magnetron Sputtering (open access)

Discharge Physics of High Power Impulse Magnetron Sputtering

High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.
Date: October 13, 2010
Creator: Anders, Andre
Object Type: Article
System: The UNT Digital Library
Thermal Degradation Behavior of Siloxane Elastomer Impregnated Carbon Nanotube Areogel Networks (open access)

Thermal Degradation Behavior of Siloxane Elastomer Impregnated Carbon Nanotube Areogel Networks

A novel class of nanoporous graphitic carbon foams has been synthesized. Unprecedented properties - electrically conductive, thermally stable (> 1000 C), and mechanically robust. Improved transport properties (DWNT-CA, SWNT-CA) - greater than 100% enhancement in thermal conductivity, 100-400% improvement in electrical conductivity. Rich mechanical deformation behavior (SWNT-CA) - stiff ({approx}100% improvement of elastic modulus), energy dissipation, fracture toughness, and fatigue behavior. Implications for energy-related technologies - hydrogen storage, fusion and fission energy, catalysis, electrochemical energy storage, and composites with foam scaffolds.
Date: December 13, 2010
Creator: Lewicki, J P & Worsley, M A
Object Type: Article
System: The UNT Digital Library