Resource Type

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1.1-meter bore, 8-Tesla test facility (open access)

1.1-meter bore, 8-Tesla test facility

The design and fabrication of a 1.1-m bore superconducting coil for an 8- T facility at Lawrence Livermore Laboratory are discussed. This facility will provide the backing field required for testing large multifilamentary Nb$sub 3$Sn coils as part of the superconductor development program at Livermore. The magnet measures 1.85 m o.d., is 1.5 m in length, and is solenoid wound in four separate modules. Total cold weight of the assembly is 18,000 Kg. A NbTi superconductor is used throughout with a gradation of current density within the magnet to provide complete cryostatic stability. The preliminary design of a large 3500-A multifilamentary Nb$sub 3$Sn insert magnet is also included. Together, the backing coil and insert magnets are designed to produce a 12-T central field in a 0.4m bore. The ''equal area'' theory of cryostatic stability is applied in the design of both magnet systems and is discussed in detail. A large open-mouth cryostat is used and measures 2 m in diameter and 3.7 m in length. Details of Dewar design and the refrigeration requirements are included. (auth)
Date: November 19, 1975
Creator: Nelson, R.; Cornish, D.; Zbasnik, J.; Sackett, S. & Taylor, C.
System: The UNT Digital Library
1-D Van der Waals Foams Heated by Ion Beam Energy Deposition (open access)

1-D Van der Waals Foams Heated by Ion Beam Energy Deposition

One dimensional simulations of various initial average density aluminum foams (modeled as slabs of solid metal separated by low density regions) heated by volumetric energy deposition are conducted with a Lagrangian hydrodynamics code using a van der Waals equation of state (EOS). The resulting behavior is studied to facilitate the design of future warm dense matter (WDM) experiments at LBNL. In the simulations the energy deposition ranges from 10 to 30 kJ/g and from 0.075 to 4.0 ns total pulse length, resulting in temperatures from approximately 1 to 4 eV. We study peak pressures and temperatures in the foams, expansion velocity, and the phase evolution. Five relevant time scales in the problem are identified. Additionally, we present a method for characterizing the level of inhomogeneity in a foam target as it is heated and the time it takes for a foam to homogenize.
Date: March 19, 2010
Creator: Zylstra, A; Barnard, J J & More, R M
System: The UNT Digital Library
2.5 MHz feedforward beam loading compensation in the Fermilab Main Injector (open access)

2.5 MHz feedforward beam loading compensation in the Fermilab Main Injector

There are five 2.5 MHz ferrite cavities (h = 28) in the Main Injector with an R/Q of 500 that are presently used for coalescing for the Tevatron. For use with the Fermilab Recycler, feedforward (FF) beam loading compensation (BLC) is required on these cavities because they will be required to operate at a net of 2 kV. Under current Recycler beam conditions, the beam-induced voltage is of this order. Recently a system using a digital bucket delay module operating at 53 MHz (h = 588) was used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the 2.5 MHz cavities to cancel the beam induced voltage. During current operation they have shown consistently to operate with over a 20 dB reduction in beam loading.
Date: May 19, 2003
Creator: Dey, Joseph E.; Kourbanis, Ioanis & Steimel, James
System: The UNT Digital Library
3,2-HOPO Complexes of Near-Infra-Red (NIR) Emitting Lanthanides: Sensitization of Ho(III) and Pr(III) in Aqueous Solution (open access)

3,2-HOPO Complexes of Near-Infra-Red (NIR) Emitting Lanthanides: Sensitization of Ho(III) and Pr(III) in Aqueous Solution

There is a growing interest in Near Infra-Red (NIR) emission originating from organic complexes of Ln{sup III} cations. As a major impetus, biological tissues are considerably more transparent at these low energy wavelengths when compared to visible radiation, which facilitates deeper penetration of incident and emitted light. Furthermore, the long luminescence lifetimes of Ln{sup III} complexes (eg. Yb{sup III}, {tau}{sub rad} {approx} 1 ms) when compared to typical organic molecules can be utilized to vastly improve signal to noise ratios by employing time-gating techniques. While the improved quantum yield of Yb{sub III} complexes when compared to other NIR emitters favors their use for bioimaging applications, there has also been significant interest in the sensitized emission from other 4f metals such as Ln = Nd, Ho, Pr and Er which have well recognized applications as solid state laser materials (eg. Nd {approx} 1.06 {micro}m, Ho {approx} 2.09 {micro}m), and in telecommunications (eg. Er {approx} 1.54 {micro}m) where they can be used for amplification of optical signals. As a result of their weak (Laporte forbidden) f-f absorptions, the direct excitation of Ln{sup III} cations is inefficient, and sensitization of the metal emission is more effectively achieved using the so-called antenna effect. We …
Date: May 19, 2008
Creator: Moore, Evan G.; Szigethy, Geza; Xu, Jide; Palsson, Lars-Olof; Beeby, Andrew & Raymond, Kenneth N.
System: The UNT Digital Library
N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop (open access)

N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop

We expose simple and practical relations between the integrated four- and five-point one-loop amplitudes of N {ge} 4 supergravity and the corresponding (super-)Yang-Mills amplitudes. The link between the amplitudes is simply understood using the recently uncovered duality between color and kinematics that leads to a double-copy structure for gravity. These examples provide additional direct confirmations of the duality and double-copy properties at loop level for a sample of different theories.
Date: August 19, 2011
Creator: Bern, Z.; Boucher-Veronneau, C. & Johansson, H.
System: The UNT Digital Library
30+ years of plasma simulation (open access)

30+ years of plasma simulation

None
Date: December 19, 1990
Creator: Langdon, B.
System: The UNT Digital Library
50 years of excellence in science and engineering at the Savannah River Site (open access)

50 years of excellence in science and engineering at the Savannah River Site

This is a collection of papers including abstracts about the celebration of 50 years of excellence in science and engineering at the Savannah River Site. The Symposium Committee invited current and former employees to nominate the innovations to be recognized. Several selection panels of experts in various technical fields reviewed 190 nominations and selected the achievements included in this proceedings. Neither the Symposium Committee nor the selection panels claim that these accomplishments are the best of the best. Instead, they believe that they typify the outstanding quality of science and engineering at the Site during its first half-century.
Date: April 19, 2000
Creator: Phillips, A G
System: The UNT Digital Library
53 MHZ Feedforward beam loading compensation in the Fermilab main injector (open access)

53 MHZ Feedforward beam loading compensation in the Fermilab main injector

53 MHz feedforward beam loading compensation is crucial to all operations of the Main Injector. Recently a system using a fundamental frequency down converter mixer, a digital bucket delay module and a fundamental frequency up converter mixer were used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the cavities to cancel the transient beam induced voltage. During operation they have shown consistently over 20 dB reduction in side-band voltage around the fundamental frequency during Proton coalescing and over 14 dB in multi-batch antiproton coalescing.
Date: May 19, 2003
Creator: al., Joseph E Dey et
System: The UNT Digital Library
938 nm Nd-Doped High Power Cladding Pumped Fiber Amplifier (open access)

938 nm Nd-Doped High Power Cladding Pumped Fiber Amplifier

2.1W of 938nm light has been produced in an Nd{sup 3+} doped fiber amplifier. Wavelength dependent bend losses can be employed to minimize 1088nm amplified spontaneous emission giving the optical fiber a distinct advantage over bulk media.
Date: September 19, 2002
Creator: Dawson, J; Beach, R; Drobshoff, A; Liao, Z; Pennington, D; Payne, S et al.
System: The UNT Digital Library
13C-Tracer Experiments in DIII-D Preliminary to Thermal Oxidation Experiments to Understand Tritium Recovery in DIII-D, JET, C-Mod, and MAST (open access)

13C-Tracer Experiments in DIII-D Preliminary to Thermal Oxidation Experiments to Understand Tritium Recovery in DIII-D, JET, C-Mod, and MAST

Retention of tritium in carbon co-deposits is a serious concern for ITER. Developing a reliable in-situ removal method of the co-deposited tritium would allow the use of carbon plasma-facing components which have proven reliable in high heat flux conditions and compatible with high performance plasmas. Thermal oxidation is a potential solution, capable of reaching even hidden locations. It is necessary to establish the least severe conditions to achieve adequate tritium recovery, minimizing damage and reconditioning time. The first step in this multi-machine project is {sup 13}C-tracer experiments in DIII-D, JET, C-Mod and MAST. In DIII-D and JET, {sup 13}CH{sub 4} has been (and in C-Mod and MAST, will be) injected toroidally symmetrically, facilitating quantification and interpretation of the results. Tiles have been removed, analyzed for {sup 13}C content and will next be evaluated in a thermal oxidation test facility in Toronto with regard to the ability of different severities of oxidation exposure to remove the different types of (known and measured) {sup 13}C co-deposit. Removal of D/T from B on Mo tiles from C-Mod will also be tested. OEDGE interpretive code analysis of the {sup 13}C deposition patterns is used to generate the understanding needed to apply findings to ITER. …
Date: June 19, 2006
Creator: Stangeby, P.; Allen, S.; Bekris, N.; Brooks, N.; Christie, K.; Chrobak, C. et al.
System: The UNT Digital Library
2007 Time_Dependent Density-Functional Therory (July 15-20, 2007 Colby College, Maine) (open access)

2007 Time_Dependent Density-Functional Therory (July 15-20, 2007 Colby College, Maine)

Time-dependent density-functional theory (TDDFT) provides an efficient, elegant, and formally exact way of describing the dynamics of interacting many-body quantum systems, circumventing the need for solving the full time-dependent Schroedinger equation. In the 20 years since it was first rigorously established in 1984, the field of TDDFT has made rapid and significant advances both formally as well as in terms of successful applications in chemistry, physics and materials science. Today, TDDFT has become the method of choice for calculating excitation energies of complex molecules, and is becoming increasingly popular for describing optical and spectroscopic properties of a variety of materials such as bulk solids, clusters and nanostructures. Other growing areas of applications of TDDFT are nonlinear dynamics of strongly excited electronic systems and molecular electronics. The purpose and scope of this Gordon Research Conference is to provide a platform for discussing the current state of the art of the rapidly progressing, highly interdisciplinary field of TDDFT, to identify and debate open questions, and to point out new promising research directions. The conference will bring together experts with a diverse background in chemistry, physics, and materials science.
Date: September 19, 2008
Creator: Gray, Ullrich Carsten Nancy Ryan
System: The UNT Digital Library
2011 Laser Diagnostics in Combustion Gordon Research Conference, (August 14-19, 2011, Waterville Valley Resort, Waterville Valley, NH) (open access)

2011 Laser Diagnostics in Combustion Gordon Research Conference, (August 14-19, 2011, Waterville Valley Resort, Waterville Valley, NH)

The vast majority of the world's energy needs are met by combustion of fossil fuels. Optimum utilization of limited resources and control of emissions of pollutants and greenhouse gases demand sustained improvement of combustion technology. This task can be satisfied only by detailed knowledge of the underlying physical and chemical processes. Non-intrusive laser diagnostics continuously contribute to our growing understanding of these complex and coupled multi-scale processes. The GRC on Laser Diagnostics in Combustion focuses on the most recent scientific advances and brings together scientists and engineers working at the leading edge of combustion research. Major tasks of the community are developing and applying methods for precise and accurate measurements of fluid motion and temperatures; chemical compositions; multi-phase phenomena appearing near walls, in spray and sooting combustion; improving sensitivities, precision, spatial resolution and tracking transients in their spatio-temporal development. The properties and behaviour of novel laser sources, detectors, optical systems that lead to new diagnostic capabilities are also part of the conference program.
Date: August 19, 2011
Creator: Settersten, Thomas
System: The UNT Digital Library
2011 Status of the Automatic Alignment System for the National Ignition Facility (open access)

2011 Status of the Automatic Alignment System for the National Ignition Facility

Automated alignment for the National Ignition Facility (NIF) is accomplished using a large-scale parallel control system that directs 192 laser beams along the 300-m optical path. The beams are then focused down to a 50-micron spot in the middle of the target chamber. The entire process is completed in less than 50 minutes. The alignment system commands 9,000 stepping motors for highly accurate adjustment of mirrors and other optics. 41 control loops per beamline perform parallel processing services running on a LINUX cluster to analyze high-resolution images of the beams and their references. This paper describes the status the NIF automatic alignment system and the challenges encountered as NIF development has transitioned from building the laser, to becoming a research project supporting a 24 hour, 7 day laser facility. NIF is now a continuously operated system where performance monitoring is increasingly more critical for operation, maintenance, and commissioning tasks. Equipment wear and the effects of high energy neutrons from fusion experiments are issues which alter alignment efficiency and accuracy. New sensors needing automatic alignment assistance are common. System modifications to improve efficiency and accuracy are prevalent. Handling these evolving alignment and maintenance needs while minimizing the impact on NIF experiment …
Date: July 19, 2011
Creator: Wilhelmsen, K.; Awwal, A.; Burkhart, S.; McGuigan, D.; Kamm, V. M.; Leach, R. et al.
System: The UNT Digital Library
2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets (open access)

2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets

A quench program using ANSYS is developed for the high field collider magnet for three-dimensional analysis. Its computational procedure is explained. The quench program is applied to a one meter Nb{sub 3}Sn high field model magnet, which is epoxy impregnated. The quench simulation program is used to estimate the temperature and mechanical stress inside the coil as well as over the whole magnet. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for longer magnets.
Date: September 19, 2002
Creator: al., Ryuji Yamada et
System: The UNT Digital Library
3D GRMHD and GRPIC Simulations of Disk-Jet Coupling and Emission (open access)

3D GRMHD and GRPIC Simulations of Disk-Jet Coupling and Emission

We investigate jet formation in black-hole systems using 3-D General Relativistic Particle-In-Cell (GRPIC) and 3-D GRMHD simulations. GRPIC simulations, which allow charge separations in a collisionless plasma, do not need to invoke the frozen condition as in GRMHD simulations. 3-D GRPIC simulations show that jets are launched from Kerr black holes as in 3-D GRMHD simulations, but jet formation in the two cases may not be identical. Comparative study of black hole systems with GRPIC and GRMHD simulations with the inclusion of radiate transfer will further clarify the mechanisms that drive the evolution of disk-jet systems.
Date: December 19, 2006
Creator: Nishikawa, Ken-Ichi; Mizuno, Y.; Watson, M.; Hardee, P.; Fuerst, S.; Wu, K. et al.
System: The UNT Digital Library
Ablation of NIF Targets and Diagnostic Components by High Power Lasers and X-Rays from High Temperature Plasmas (open access)

Ablation of NIF Targets and Diagnostic Components by High Power Lasers and X-Rays from High Temperature Plasmas

The National Ignition Facility (NIF) will consist of 192 laser beams that have a total energy of up to 1.8 MJ in the 3rd harmonic ({lambda} = 0.35 {micro}m) with the amount of 2nd harmonic and fundamental light depending on the pulse shape. Material near best focus of the 3rd harmonic light will be vaporized/ablated very rapidly, with a significant fraction of the laser energy converted into plasma x rays. Additional plasma x rays can come from imploding/igniting capsule inside Inertial Confinement Fusion (ICF) hohlraums. Material from outer portions of the target, diagnostic components, first-wall material, and optical components, are ablated by the plasma x rays. Material out to a radius of order 3 cm from target center is also exposed to a significant flux of 2nd harmonic and fundamental laser light. Ablation can accelerate the remaining material to high velocities if it has been fragmented or melted. In addition, the high velocity debris wind of the initially vaporized material pushes on the fragments/droplets and increases their velocity. The high velocity shrapnel fragments/droplets can damage the fused silica shields protecting the final optics in NIF. We discuss modeling efforts to calculate vaporization/ablation, x-ray generation, shrapnel production, and ways to mitigate …
Date: April 19, 2000
Creator: Eder, D. C.; Anderson, A. T.; Braun, D. G. & Tobin, M. T.
System: The UNT Digital Library
An abstract approach to music. (open access)

An abstract approach to music.

In this article we have outlined a formal framework for an abstract approach to music and music composition. The model is formulated in terms of objects that have attributes, obey relationships, and are subject to certain well-defined operations. The motivation for this approach uses traditional terms and concepts of music theory, but the approach itself is formal and uses the language of mathematics. The universal object is an audio wave; partials, sounds, and compositions are special objects, which are placed in a hierarchical order based on time scales. The objects have both static and dynamic attributes. When we realize a composition, we assign values to each of its attributes: a (scalar) value to a static attribute, an envelope and a size to a dynamic attribute. A composition is then a trajectory in the space of aural events, and the complex audio wave is its formal representation. Sounds are fibers in the space of aural events, from which the composer weaves the trajectory of a composition. Each sound object in turn is made up of partials, which are the elementary building blocks of any music composition. The partials evolve on the fastest time scale in the hierarchy of partials, sounds, and …
Date: April 19, 1999
Creator: Kaper, H. G. & Tipei, S.
System: The UNT Digital Library
Accelerator-based fusion with a low temperature target (open access)

Accelerator-based fusion with a low temperature target

This article reports a study of a cold target with a high Fermi energy in light of recent research that points to a new phase of hydrogen, which is hypothesized to be related to metallic hydrogen. It has been shown that if the energy transfer between injected ions and target electrons is sufficiently small, net energy gain can be achieved. As such, the target is considered to be composed of nuclei and delocalized electrons.
Date: April 19, 2013
Creator: Phillips, R. E. & Ordonez, Carlos A.
System: The UNT Digital Library
Accelerator mass spectrometry for quantitative in vivo tracing (open access)

Accelerator mass spectrometry for quantitative in vivo tracing

Accelerator mass spectrometry (AMS) counts individual rare, usually radio-, isotopes such as radiocarbon at high efficiency and specificity in milligram-sized samples. AMS traces very low chemical doses ({micro}g) and radiative doses (100 Bq) of isotope labeled compounds in animal models and directly in humans for pharmaceutical, nutritional, or toxicological research. Absorption, metabolism, distribution, binding, and elimination are all quantifiable with high precision after appropriate sample definition.
Date: April 19, 2005
Creator: Vogel, J S
System: The UNT Digital Library
Accessing the Distribution of Linearly Polarized Gluons in Unpolarized Hadrons (open access)

Accessing the Distribution of Linearly Polarized Gluons in Unpolarized Hadrons

Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos2{phi} asymmetries in heavy quark pair or dijet production in electron-hadron collisions. Future Electron-Ion Collider (EIC) or Large Hadron electron Collider (LHeC) experiments are ideally suited for this purpose. Here we estimate the maximum asymmetries for EIC kinematics.
Date: August 19, 2011
Creator: Boer, Daniel; Brodsky, Stanley J.; Mulders, Piet J. & Pisano, Cristian
System: The UNT Digital Library
Accurate solution algorithms for incompressible multiphase flows (open access)

Accurate solution algorithms for incompressible multiphase flows

A number of advances in modeling multiphase incompressible flow are described. These advances include high-order Godunov projection methods, piecewise linear interface reconstruction and tracking and the continuum surface force model. Examples are given.
Date: October 19, 1994
Creator: Rider, W. J.; Kothe, D. B.; Mosso, S. J.; Cerutti, J. H. & Hochstein, J. I.
System: The UNT Digital Library
ACLMPL: Portable and efficient message passing for MPPs (open access)

ACLMPL: Portable and efficient message passing for MPPs

This paper presents the Advanced Computing Lab Message Passing Library (ACLMPL). Modeled after Thinking Machines Corporation`s CMMD, ACLMPL is a high throughout, low latency communications library for building message passing applications. The library has been implemented on the Cray T3D, Thinking Machines CM-5, SGI workstations, and on top of PVM. On the Cray T3D, benchmarks show ACLMPL to be 4 to 7 times faster than MPI or PVM.
Date: September 19, 1995
Creator: Painter, J.; Krogh, M.; Hansen, C.; McCormick, P. & de Verdiere, G.C.
System: The UNT Digital Library
Acoustic Monitor for Solids and Gas Measurements at Low Volume Fractions (open access)

Acoustic Monitor for Solids and Gas Measurements at Low Volume Fractions

This presentation was given at the DOE Office of Science-Environmental Management Science Program (EMSP) High-Level Waste Workshop held on January 19-20, 2005 at the Savannah River Site.
Date: January 19, 2005
Creator: Tavlarides, Lawrence L.
System: The UNT Digital Library
Actinic Inspection of EUV Programmed Multilayer Defects and Cross-Comparison Measurements (open access)

Actinic Inspection of EUV Programmed Multilayer Defects and Cross-Comparison Measurements

The production of defect-free mask blanks remains a key challenge for extreme ultraviolet (EUV) lithography. Integral to this effort is the development and characterization of mask inspection tools that are sensitive enough to detect critical defects with high confidence. Using a single programmed-defect mask with a range of buried bump-type defects, we report a comparison of measurements made in four different mask-inspection tools: one commercial tool using 488-nm wavelength illumination, one prototype tool that uses 266-nm illumination, and two non-commercial EUV ''actinic'' inspection tools. The EUV tools include a darkfield imaging microscope and a scanning microscope. Our measurements show improving sensitivity with the shorter wavelength non-EUV tool, down to 33-nm spherical-equivalent-volume diameter, for defects of this type. Measurements conditions were unique to each tool, with the EUV tools operating at a much slower inspection rate. Several defects observed with EUV inspection were below the detection threshold of the non-EUV tools.
Date: June 19, 2006
Creator: Goldberg, K.; Barty, A.; Liu, Y.; Kearney, P.; Tezuka, Y.; Terasawa, T. et al.
System: The UNT Digital Library