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Fusion power demonstration - a baseline for the mirror engineering test reactor (open access)

Fusion power demonstration - a baseline for the mirror engineering test reactor

Developing a definition of an engineering test reactor (ETR) is a current goal of the Office of Fusion Energy (OFE). As a baseline for the mirror ETR, the Fusion Power Demonstration (FPD) concept has been pursued at Lawrence Livermore National Laboratory (LLNL) in cooperation with Grumman Aerospace, TRW, and the Idaho National Engineering Laboratory. Envisioned as an intermediate step to fusion power applications, the FPD would achieve DT ignition in the central cell, after which blankets and power conversion would be added to produce net power. To achieve ignition, a minimum central cell length of 67.5 m is needed to supply the ion and alpha particles radial drift pumping losses in the transition region. The resulting fusion power is 360 MW. Low electron-cyclotron heating power of 12 MW, ion-cyclotron heating of 2.5 MW, and a sloshing ion beam power of 1.0 MW result in a net plasma Q of 22. A primary technological challenge is the 24-T, 45-cm bore choke coil, comprising a copper hybrid insert within a 15 to 18 T superconducting coil.
Date: December 2, 1983
Creator: Henning, C. D.; Logan, B. G.; Neef, W. S.; Dorn, D.; Clarkson, I. R.; Carpenter, T. et al.
System: The UNT Digital Library
Radiation-induced electrical breakdown of helium in fusion reactor superconducting magnet systems (open access)

Radiation-induced electrical breakdown of helium in fusion reactor superconducting magnet systems

A comprehensive theoretical study has been performed on the reduction of the electrical breakdown potential of liquid and gaseous helium under neutron and gamma radiation. Extension of the conventional Townsend breakdown theory indicates that radiation fields at the superconducting magnets of a typical fusion reactor are potentially capable of significantly reducing currently established (i.e., unirradiated) helium breakdown voltages. Emphasis is given to the implications of these results including future deployment choices of magnet cryogenic methods (e.g., pool-boiling versus forced-flow), the possible impact on magnet shielding requirements and the analogous situation for radiation-induced electrical breakdown in fusion RF transmission systems.
Date: December 2, 1983
Creator: Perkins, L.J.
System: The UNT Digital Library
Calculation of density profiles in tandem mirrors fueled by pellets (open access)

Calculation of density profiles in tandem mirrors fueled by pellets

We have modified the LLNL radial transport code TMT to model reactor regime plasmas, fueled by pellets. The source profiles arising from pellet fueling are obtained from existing pellet ablation models. Because inward radial diffusion due to inverted profiles must compete with trapping of central cell ions in the transition region for tandem mirrors, pellets must penetrate fairly far into the plasma. In fact, based on our radial calculations, a pellet with a velocity of 10 km/sec cannot sustain the central flux tubes; a velocity more like 100 km/sec will be necessary. We also find that the central cell radial diffusion must exceed classical by about a factor of 100.
Date: December 2, 1983
Creator: Campbell, R. B. & Gilmore, J. M.
System: The UNT Digital Library
Tandem mirror fusion research (open access)

Tandem mirror fusion research

The tandem mirror program has evolved considerably in the last decade. Of significance is the viable reactor concept embodied in the MARS design. An aggressive experimental program, culminating in the operation of MFTF-B in late 1986, will provide a firm basis for refining the MARS design as necessary for constructing a reactor prototype in the 1990s.
Date: December 2, 1983
Creator: Baldwin, D.E.
System: The UNT Digital Library
Tandem mirror experiment-upgrade vacuum system: a new configuration and operating parameters (open access)

Tandem mirror experiment-upgrade vacuum system: a new configuration and operating parameters

The Tandem Mirror Experiment-Upgrade (TMX-U) vacuum system has been installed and operating since December 1981. In 1982 and early 1983 the performance of the internal, dynamic pumping system was evaluated during physics experiments. The plasma region gas loads caused the pressure to exceed that allowable for achieving thermal barrier plasmas. The unified, multiple-beamline concept used on TMX-U to pump the neutral-beam injector gas was modified. The modifications to the system were designed to reduce conductance between the injectors and the plasma region to better use the differential pumping in the pumping regions. The modifications made were a smaller cross section neutralizer, replacing apertures with ducts between regions, eliminating the injector scrape-off in the plasma region, relocating the neutral beam dumps, and eliminating the gaps around various penetrations.
Date: December 2, 1983
Creator: Lang, D. D.; Calderon, M. O.; Hunt, A.; Nexsen, W. E.; Pickles, W. L. & Turner, W. C.
System: The UNT Digital Library
Reaction chemistry and ligand exchange at cadmium selenide nanocrystal surfaces (open access)

Reaction chemistry and ligand exchange at cadmium selenide nanocrystal surfaces

Chemical modification of nanocrystal surfaces is fundamentally important to their assembly, their implementation in biology and medicine, and greatly impacts their electrical and optical properties. However, it remains a major challenge owing to a lack of analytical tools to directly determine nanoparticle surface structure. Early nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) studies of CdSe nanocrystals prepared in tri-n-octylphosphine oxide (1) and tri-n-octylphosphine (2), suggested these coordinating solvents are datively bound to the particle surface. However, assigning the broad NMR resonances of surface-bound ligands is complicated by significant concentrations of phosphorus-containing impurities in commercial sources of 1, and XPS provides only limited information about the nature of the phosphorus containing molecules in the sample. More recent reports have shown the surface ligands of CdSe nanocrystals prepared in technical grade 1, and in the presence of alkylphosphonic acids, include phosphonic and phosphinic acids. These studies do not, however, distinguish whether these ligands are bound datively, as neutral, L-type ligands, or by X-type interaction of an anionic phosphonate/phosphinate moiety with a surface Cd{sup 2+} ion. Answering this question would help clarify why ligand exchange with such particles does not proceed generally as expected based on a L-type ligand model. By …
Date: December 2, 2008
Creator: Owen, Jonathan; Park, Jungwon; Trudeau, Paul-Emile & Alivisatos, A. Paul
System: The UNT Digital Library
A Quasicontinuum Study of Nanovoid Collapse under Uniaxial Loading in Ta (open access)

A Quasicontinuum Study of Nanovoid Collapse under Uniaxial Loading in Ta

The mechanisms underlying the deformation of nanovoids in Ta single crystals are analyzed when they are subjected to cyclic uniaxial deformation using numerical simulations. Boundary and cell-size effects have been mitigated by means of the Quasicontinuum (QC) method. We have considered {approx} 1 billion-atom systems containing 10.9 nm voids. Two kinds of simulations have been performed, each characterized by a different boundary condition. First, we compress the material along the nominal [0 0 1] direction, resulting in a highly symmetric configuration that results in high stresses. Second, we load the material along the high-index [{bar 4}819] direction to confine plasticity to a single slip system and break the symmetry. We find that the plastic response under these two conditions is strikingly different, the former governed by dislocation loop emission and dipole formation, while the latter is dominated by twinning. We calculate the irreversible plastic work budget derived from a loading-unloading cycle and identify the most relevant yield points. These calculations represent the first fully three-dimensional, fully non-local simulations of any body-centered cubic metal using QC.
Date: December 2, 2007
Creator: Marian, J.; Knap, J. & Campbell, G.
System: The UNT Digital Library
Effects of the Noncommutative Standard Model in WW Scattering (open access)

Effects of the Noncommutative Standard Model in WW Scattering

We examine W pair production in the Noncommutative Standard Model constructed with the Seiberg-Witten map. Consideration of partial wave unitarity in the reactions WW {yields} WW and e{sup +}e{sup -} {yields} WW shows that the latter process is more sensitive and that tree-level unitarity is violated when scattering energies are of order a TeV and the noncommutative scale is below about a TeV. We find that WW production at the LHC is not sensitive to scales above the unitarity bounds. WW production in e{sup +}e{sup -} annihilation, however, provides a good probe of such effects with noncommutative scales below 300-400 GeV being excluded at LEP-II, and the ILC being sensitive to scales up to 10-20 TeV. In addition, we find that the ability to measure the helicity states of the final state W bosons at the ILC provides a diagnostic tool to determine and disentangle the different possible noncommutative contributions.
Date: December 2, 2008
Creator: Conley, John A. & Hewett, JoAnne L.
System: The UNT Digital Library
Is CR39 worth the effort (open access)

Is CR39 worth the effort

CR39 proton sensitive track detectors were greeted by the radiation protection community at the end of the last decade as a major breakthrough for personnel neutron dosimetry. A number of laboratories eagerly began research on application of CR39 to their dosimetry needs. However, in the last two or three years the enthusiasm has subsided, and many health physicists have stopped working with the material. The number of participants using CR39 in the Oak Ridge National Laboratory Personnel Intercomparison Studies dropped from six in 1985 to three in 1986. On a national level, the Federal Republic of Germany with researchers active in CR39 research recently adopted an albedo system as their national standard. In contrast, the United States Department of Energy (DOE) is supporting development of a CR39 based combination dosimeter to meet Department wide dosimetry needs. The English National Radiological Protection Board (NRPB) now features the use of CR39 in the NRPB PADC(CR39). There has obviously been a range of experiences with CR39 in the dosimetry community. Why has this been the case, and what is the proper role for CR39 in personnel neutron dosimetry. 12 refs., 2 figs., 1 tab.
Date: December 2, 1987
Creator: Griffith, R.V.
System: The UNT Digital Library
Neutron scattering from charged polymer lattices (open access)

Neutron scattering from charged polymer lattices

Aqueous suspensions of charged polymer latex particles exhibit several forms of ordered structure, the particular form depending on the size, number density and charge of the latex particles, and on the ionic strength of the aqueous medium. At low ionic strength, the inter-particle potential may become sufficiently long-ranged to generate crystalline order, which usually shows bcc symmetry at low density and becomes fcc above about 3% volume fraction of latex in the system. As the ionic strength increases, the crystalline structure melts, and ordered liquid structures develop. This paper reviews some of the recent small-angle neutron scattering experiments on polymer latex suspensions, in the light of new theoretical methods which permit in situ analysis of the particle size and charge. The discussion also encompasses new experimental methods for studying latex structures under dynamic shear conditions.
Date: December 2, 1987
Creator: Hayter, J. B.
System: The UNT Digital Library
Tandem mirror experiment upgrade (TMX-U) throttle, mechanical design, construction, installation, and alignment (open access)

Tandem mirror experiment upgrade (TMX-U) throttle, mechanical design, construction, installation, and alignment

We will soon add a high-field axisymmetric throttle region to the central cell of the TMX-U. Field amplitude will be adjusted between 2.25 and 6.0 T. This field is produced by adding a high-field solenoid and a cee coil to each end of the central cell. We describe these coils as well as the additions to the restraint structure. We analyzed the stresses within the solenoid using the STANSOL code. In addition, we performed a finite-element structural analysis of the complete magnet set with the SAP4 code. Particular attention was paid to the transition section where the new magnets were added and where the currents in the existing magnets were increased. The peak temperature rise in the throttle coil was calculated to be 41/sup 0/C above ambient.
Date: December 2, 1983
Creator: Pedrotti, L.R. & Wong, R.L.
System: The UNT Digital Library
On-line liquid-effluent monitoring of sewage at Lawrence Livermore National Laboratory (open access)

On-line liquid-effluent monitoring of sewage at Lawrence Livermore National Laboratory

An automatic on line sewage effluent monitoring system has been developed. A representative fraction of the total waste stream leaving the site is monitored for pH, radiation, and metals as it passes through a detection assembly. This assembly consists of an industrial pH probe, NaI radiation detectors, and an x-ray fluorescence metal detector. A microprocessor collects, reduces and analyzes the data to determine if the levels are acceptable by established environmental limits. Currently, if preset levels are exceeded, a sample of the suspect sewage is automatically collected for further analysis, and an alarm is sent to a station where personnel can be alerted to respond on a 24-hour basis. Since at least four hours pass before LLNL effluent reaches the treatment plant, sufficient time is available to alert emergency personnel, evaluate the situation, and if necessary arrange for diversion of the material to emergency holding basins at the treatment plant. Information on the current system is presented, and progress is reported in developing an on-line tritium monitor as an addition to the assembly.
Date: December 2, 1982
Creator: Dreicer, M.; Cate, J.L.; Rueppel, D.W.; Huntzinger, C.J. & Gonzalez, M.A.
System: The UNT Digital Library
The use of TPC's as target region detectors in the MPS (open access)

The use of TPC's as target region detectors in the MPS

None
Date: December 2, 1988
Creator: Foley, K.J.
System: The UNT Digital Library
Strongly coupled ionic mixtures and the H/He EOS (open access)

Strongly coupled ionic mixtures and the H/He EOS

This paper summarizes recent work on the strongly coupled OCP and Binary Ionic Mixture equation of state and other thermodynamic quantities in white dwarf interior conditions for both fluid and solid phases with the assumption of a uniform background. Conditions for phase separation of different elements in fluid or solid phases is strongly dependent on deviations from the linear mixing rule which gives the equation of state as an additive function of the OCP equation of state. These deviations turn out to be small (a few parts in 10{sup 5}) and always positive including the case where the fraction of the higher Z component approaches 0. Also the equation of state of strongly coupled light elements (H and He particularly) obtained from simulations with a linear response description of the electrons is given for conditions appropriate to brown dwarf star interiors. Recent Livermore work on a band structure calculation of the enthalpy of H and He mixtures under jovian conditions is discussed. This work leads to a prediction of a high temperature (15,000 K) for miscibility of He in ionized H at 10 Mb.
Date: December 2, 1993
Creator: DeWitt, H. E.
System: The UNT Digital Library
Overview of the Chemical Weapons Convention (open access)

Overview of the Chemical Weapons Convention

My subject this morning is a very brief overview of the Chemical Weapons Convention. Much has already been written describing and summarizing the Convention, including several of the Supplementary Papers and the Annex contained within the draft Manual. It is not my goal to restate what many of you already know. Rather, in the short time available, I want to focus on the parts of the Convention that are addressed in the draft Manual, that is, I want to highlight for you those aspects of the CWC that require implementation by individual State Parties. As I do so, I will show you where in the draft Manual each of these matters is addressed so that you can see how our document corresponds to the Convention`s requirements. This will provide a bridge between the plenary sessions and workshops that will consider the implementing measures and the Supplementary Papers in the Manual. In organizing my talk to focus on aspects of the Convention requiring national implementing measures, I necessarily leave out certain of its provisions. Among these intentional omissions are, with all due respect to our hosts, the structure and function of the OPCW, the Annex on Chemicals, and various operational aspects …
Date: December 2, 1993
Creator: Tanzman, E. A.
System: The UNT Digital Library
Search for 14.4-KeV Solar Axions Emitted in the M1-Transition of Fe-57 Nuclei with CAST (open access)

Search for 14.4-KeV Solar Axions Emitted in the M1-Transition of Fe-57 Nuclei with CAST

We have searched for 14.4 keV solar axions or more general axion-like particles (ALPs), that may be emitted in the M1 nuclear transition of 57Fe, by using the axion-to-photon conversion in the CERN Axion Solar Telescope (CAST) with evacuated magnet bores (Phase I). From the absence of excess of the monoenergetic X-rays when the magnet was pointing to the Sun, we set model-independent constraints on the coupling constants of pseudoscalar particles that couple to two photons and to a nucleon g{sub ay}|-1.19g{sub aN}{sup 0}+g{sub aN}{sup 3}| < 1.36 x 10{sup -16} GeV{sup -1} for ma < 0.03 eV at the 95% confidence level.
Date: December 2, 2011
Creator: Andriamonje, S.; Aune, S.; Autiero, D.; Barth, K.; Belov, A.; Beltran, B. et al.
System: The UNT Digital Library
The developmental transcriptome of Drosophila melanogaster (open access)

The developmental transcriptome of Drosophila melanogaster

Drosophila melanogaster is one of the most well studied genetic model organisms; nonetheless, its genome still contains unannotated coding and non-coding genes, transcripts, exons and RNA editing sites. Full discovery and annotation are pre-requisites for understanding how the regulation of transcription, splicing and RNA editing directs the development of this complex organism. Here we used RNA-Seq, tiling microarrays and cDNA sequencing to explore the transcriptome in 30 distinct developmental stages. We identified 111,195 new elements, including thousands of genes, coding and non-coding transcripts, exons, splicing and editing events, and inferred protein isoforms that previously eluded discovery using established experimental, prediction and conservation-based approaches. These data substantially expand the number of known transcribed elements in the Drosophila genome and provide a high-resolution view of transcriptome dynamics throughout development. Drosophila melanogaster is an important non-mammalian model system that has had a critical role in basic biological discoveries, such as identifying chromosomes as the carriers of genetic information and uncovering the role of genes in development. Because it shares a substantial genic content with humans, Drosophila is increasingly used as a translational model for human development, homeostasis and disease. High-quality maps are needed for all functional genomic elements. Previous studies demonstrated that a …
Date: December 2, 2010
Creator: Connecticut, University of; Graveley, Brenton R.; Brooks, Angela N.; Carlson, Joseph W.; Duff, Michael O.; Landolin, Jane M. et al.
System: The UNT Digital Library
Silo & HDF5 I/O Scaling Improvements on BG/P Systems (open access)

Silo & HDF5 I/O Scaling Improvements on BG/P Systems

Silo and HDF5 are I/O libraries used by many codes important to the LLNL's Weapons and Complex Integration (WCI) mission. In the past year, modest adjustments and tuning of Silo, HDF5 and the I/O configuration of the BG/P platform, Dawn, were undertaken. A key goal of this work was to improve I/O performance without requiring any changes in the application codes themselves. In particular, the application codes have been allowed to continue to use a simplified yet highly flexible I/O paradigm known as 'Poor Man's Parallel I/O', where scalability is achieved through concurrent, serial I/O to multiple files. The results demonstrate substantial performance gains (better than 50x in many cases) at large scale (greater than 64,000 MPI tasks). They describe key enhancements made to Silo, HDF5 and the I/O configuration of our BG/P platform and present very favorable results from scalability studies over a wide range of operating scenarios.
Date: December 2, 2010
Creator: Collette, M R & Miller, M C
System: The UNT Digital Library
Results on Searches for New Physics at B Factories (open access)

Results on Searches for New Physics at B Factories

We summarize recent results on B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}} setting constraints on the charged Higgs mass, discuss the CP puzzle in B {yields} K{pi} decays and present searches for a light neutral Higgs in radiative {Upsilon}(2S) and {Upsilon}(3S) decays. Rare decays are processes with branching fractions of {Omicron}(10{sup -4}) or smaller. Typically, they arise if amplitudes of higher-order processes (penguin loops, box diagrams) become dominant because tree amplitudes are suppressed in the Standard Model (SM). Additional suppression comes from small CKM couplings and helicity conservation. Contributions of New Physics (NP) processes may become significant modifying the prediction with respect to those in the SM. Thus, rare decays provide an interesting hunting ground for NP searches that are complementary to direct searches at the LHC.
Date: December 2, 2011
Creator: Eigen, Gerald
System: The UNT Digital Library
A Systems Framework for Assessing Plumbing Products-Related Water Conservation (open access)

A Systems Framework for Assessing Plumbing Products-Related Water Conservation

Reducing the water use of plumbing products—toilets, urinals, faucets, and showerheads —has been a popular conservation measure. Improved technologies have created opportunities for additional conservation in this area. However, plumbing products do not operate in a vacuum. This paper reviews the literature related to plumbing products to determine a systems framework for evaluating future conservation measures using these products. The main framework comprises the following categories: water use efficiency, product components, product performance, source water, energy, and plumbing/sewer infrastructure. This framework for analysis provides a starting point for professionals considering future water conservation measures to evaluate the need for additional research, collaboration with other standards or codes committees, and attachment of additional metrics to water use efficiency (such as performance).
Date: December 2, 2011
Creator: Williams, Alison; Dunham Whitehead, Camilla & Lutz, James
System: The UNT Digital Library
Recent Progress of RF Cavity Study at Mucool Test Area (open access)

Recent Progress of RF Cavity Study at Mucool Test Area

Summar of presentation is: (1) MTA is a multi task working space to investigate RF cavities for R&D of muon beam cooling channel - (a) Intense 400 MeV H{sup -} beam, (b) Handle hydrogen (flammable) gas, (c) 5 Tesla SC solenoid magnet, (d) He cryogenic/recycling system; (2) Pillbox cavity has been refurbished to search better RF material - Beryllium button test will be happened soon; (3) E x B effect has been tested in a box cavity - Under study (result seems not to be desirable); (4) 201 MHz RF cavity with SRF cavity treatment has been tested at low magnetic field - (a) Observed some B field effect on maximum field gradient and (b) Further study is needed (large bore SC magnet will be delivered end of 2011); and (5) HPRF cavity beam test has started - (a) No RF breakdown observed and (b) Design a new HPRF cavity to investigate more plasma loading effect.
Date: December 2, 2011
Creator: Yonehara, Katsuya
System: The UNT Digital Library
"Defense-in-Depth" Laser Safety and the National Ignition Facility (open access)

"Defense-in-Depth" Laser Safety and the National Ignition Facility

The National Ignition Facility (NIF) is the largest and most energetic laser in the world contained in a complex the size of a football stadium. From the initial laser pulse, provided by telecommunication style infrared nanoJoule pulsed lasers, to the final 192 laser beams (1.8 Mega Joules total energy in the ultraviolet) converging on a target the size of a pencil eraser, laser safety is of paramount concern. In addition to this, there are numerous high-powered (Class 3B and 4) diagnostic lasers in use that can potentially send their laser radiation travelling throughout the facility. With individual beam paths of up to 1500 meters and a workforce of more than one thousand, the potential for exposure is significant. Simple laser safety practices utilized in typical laser labs just don't apply. To mitigate these hazards, NIF incorporates a multi layered approach to laser safety or 'Defense in Depth.' Most typical high-powered laser operations are contained and controlled within a single room using relatively simplistic controls to protect both the worker and the public. Laser workers are trained, use a standard operating procedure, and are required to wear Personal Protective Equipment (PPE) such as Laser Protective Eyewear (LPE) if the system is …
Date: December 2, 2010
Creator: King, J. J.
System: The UNT Digital Library
Characterization of Large Area APDs for the EXO-200 Detector (open access)

Characterization of Large Area APDs for the EXO-200 Detector

EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.
Date: December 2, 2011
Creator: Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C. Y. et al.
System: The UNT Digital Library
Analytic properties of the OCP and ionic mixtures in the strongly coupled fluid state (open access)

Analytic properties of the OCP and ionic mixtures in the strongly coupled fluid state

Exact results for the Madelung constants and first order anharmonic energies are given for the inverse power potentials with the Coulomb potential as the softest example. Similar exact results are obtained using the analysis of Rosenfeld on the {Gamma} {yields} {infinity} limit for the OCP internal energy, direct correlation function, screening function, and bridge functions. Knowing these exact limits for the fluid phase of the OCP allows one to determine the nature of the thermal corrections to the strongly coupled results. Solutions of the HNC equation modified with the hard sphere bridge function give an example.
Date: December 2, 1993
Creator: DeWitt, H. E.
System: The UNT Digital Library