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RF gas plasma source development for heavy ion fusion (open access)

RF gas plasma source development for heavy ion fusion

Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50-2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamlets ion temperature is below a few eV. Thus, a RF multicusp source capable of high current density can produce beams with better brightness compared to ones extracted from a colder source with a large aperture and lower current density. As such, experiments have begun to develop a RF multicusp source capable of delivering one amp of extracted beam current. It is expected that it will require 10 kW of 13 MHz RF power delivered via a quartz shielded, one and half turn, four inch diameter antenna. Important considerations in the development of the source include the dependence of current density and beam ion temperature on consumed RF power and gas pressure. A fast rise time ({approx}100 ns) for the extracted beam pulse must also …
Date: February 22, 2002
Creator: Ahle, L.E.; Hall, R.P. & Molvik, A.W.
System: The UNT Digital Library
Scanning Tunneling Microscopy Observation of Phonon Condensate (open access)

Scanning Tunneling Microscopy Observation of Phonon Condensate

This article discusses results showing that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance.
Date: February 22, 2017
Creator: Altfeder, Igor; Voevodin, Andrey A.; Check, Michael H.; Eichfeld, Sarah M.; Robinson, Joshua A. & Balatsky, Alexander V.
System: The UNT Digital Library
Measurement of Low Energy e+e- Interactions at BABARwith Initial State Radiation (open access)

Measurement of Low Energy e+e- Interactions at BABARwith Initial State Radiation

The status of the analysis of e{sup +}e{sup -} annihilation using the radiative return technique at BaBar is presented. Cross sections for the processes e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0}, {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}, {pi}{sup +}{pi}{sup -}K{sup +}K{sup -}, K{sup +}K{sup -}K{sup +}K{sup -}, 3({pi}{sup +}{pi}{sup -}), {pi}{sup 0}{pi}{sup 0}2({pi}{sup +}{pi}{sup -}), K{sup +}K{sup -}2({pi}{sup +}{pi}{sup -}) and p{bar p} are measured in the energy range from threshold up to 4.5 GeV. Studies on resonant structures involved in these processes have been performed. We present also new precise measurements of the effective proton form factor and of the ratio of the electric to magnetic proton form factor, |G{sub E}/G{sub M}|. In addition, the J/{psi} and {psi}(2S) branching fractions to all these final states have been measured.
Date: February 22, 2006
Creator: Anulli, F.
System: The UNT Digital Library
THE BC CRIBS & TRENCHES GEOPHYSICAL CHARACTERIZATION PROJECT ONE STEP FORWARD IN HANFORDS CLEANUP PROCESS (open access)

THE BC CRIBS & TRENCHES GEOPHYSICAL CHARACTERIZATION PROJECT ONE STEP FORWARD IN HANFORDS CLEANUP PROCESS

A geophysical characterization project was conducted at the BC Cribs and Trenches Area, located south of 200 East at the Hanford Site. The area consists of 26 waste disposal trenches and cribs, which received approximately 30 million gallons of liquid waste from the uranium recovery process and the ferrocyanide processes associated with wastes generated by reprocessing nuclear fuel. Waste discharges to BC Cribs contributed perhaps the largest liquid fraction of contaminants to the ground in the 200 Areas. The site also includes possibly the largest inventory of Tc-99 ever disposed to the soil at Hanford with an estimated quantity of 400 Ci. Other waste constituents included high volumes of nitrate and U-238. The geophysical characterization at the 50 acre site primarily included high resolution resistivity (HRR). The resistivity technique is a non-invasive method by which electrical resistivity data are collected along linear transects, and data are presented as continuous profiles of subsurface electrical properties. The transects ranged in size from about 400-700 meters and provided information down to depths of 60 meters. The site was characterized by a network of 51 HRR lines with a total of approximately 19.7 line kilometers of data collected parallel and perpendicular to the trenches …
Date: February 22, 2006
Creator: BENECKE, MN.W.
System: The UNT Digital Library
Current status of dense ceramic membranes for hydrogen separation. (open access)

Current status of dense ceramic membranes for hydrogen separation.

We have developed cermet membranes that nongalvanically separate hydrogen from gas mixtures. The highest measured hydrogen flux was 16.2 cm{sup 3} (STP)/min-cm{sup 2} for an ANL-3a membrane at 900 C. For ANL-3 membranes with thickness of 0.04-0.5 mm, permeation rate is limited by the bulk diffusion of hydrogen through the metal phase. The effect of hydrogen partial pressure on permeation rate confirmed this conclusion and suggested that higher permeation rates may be obtained by decreasing the membrane thickness. Permeation rate in a syngas atmosphere for times up to 190 h showed no degradation in performance, which indicates that ANL-3 may be suitable for long-term, practical hydrogen separation.
Date: February 22, 2002
Creator: Balachandran, U.; Lee, T. H.; Wang, S.; Zhang, G. & Dorris, S. E.
System: The UNT Digital Library
Study of F- Production in BaBar RPCs (open access)

Study of F- Production in BaBar RPCs

The BaBar detector has operated over 200 2nd generation Resistive Plate Chambers (RPCs) in the forward endcap since 2002. Many chambers have increased noise rates and high voltage currents. These aging symptoms are correlated with the integrated RPC current as expected, but also depend on the rate and direction of the gas flow, indicating that pollutants produced in the gas can accelerate aging of downstream RPC surfaces. HF produced by decomposition of the Freon 134a component of the BaBar RPC gas in electric discharges has been proposed as the main pollutant. This paper presents measurements of HF production and absorption rates in BaBar RPCs. Since many of the highest rate chambers in the forward endcap were converted to avalanche mode operation, a comparison of HF production in streamer and avalanche mode RPCs is made. Correlations between the HF production rate and other chamber operating conditions were also explored.
Date: February 22, 2008
Creator: Band, H.R.; /Wisconsin U., Madison; Bellini, F.; /Rome U. /INFN, Rome; Covarelli, R.; /Perugia U. /INFN, Perugia et al.
System: The UNT Digital Library
Heavy ion inertial fusion: interface between target gain, accelerator phase space and reactor beam transport revisited (open access)

Heavy ion inertial fusion: interface between target gain, accelerator phase space and reactor beam transport revisited

Recently revised estimates of target gain have added additional optimistic inputs to the interface between targets, accelerators and fusion chamber beam transport. But it remains valid that neutralization of the beams in the fusion chamber is useful if ion charge state Z > 1 or if > 1 kA per beamlet is to be propagated. Some engineering and economic considerations favor higher currents.
Date: February 22, 1984
Creator: Barletta, W. A.; Fawley, W. M.; Judd, D. L.; Mark, J. W. K. & Yu, S. S.
System: The UNT Digital Library
Facts About XLDB-2011 (open access)

Facts About XLDB-2011

This note provides details of the 5th Extremely Large Databases Conference and Invitational Workshop that were held in 2011 on 18-19 October and 20 October, respectively, at the SLAC National Accelerator Laboratory in Menlo Park, California. The main goals of the conference were: (1) Encourage and accelerate the exchange of ideas between users trying to build extremely large databases worldwide and database solution providers; (2) Share lessons, trends, innovations, and challenges related to building extremely large databases; (3) Facilitate the development and growth of practical technologies for extremely large databases; and (4) Strengthen, expand, and engage the XLDB community.
Date: February 22, 2012
Creator: Becla, Jacek; Lim, Kian-Tat & Wang, Daniel L.
System: The UNT Digital Library
Developing hands-on ergonomics lessons for youth (open access)

Developing hands-on ergonomics lessons for youth

By the time students are ready to enter the workforce they have been exposed to up to 20 years of ergonomics risk factors. As technology evolves, it provides more opportunities for intensive repetitive motion and with computers, cell phones, personal digital assistants (PDAs), and electronic games. The average student engages in fewer active physical activities, sit stationary in mismatched furniture in schools for hours and carry heavy backpacks. While long-term effects remain to be identified, increasingly ergonomists and others concerned with musculoskeletal health and wellness, see a need for early ergonomics education. This interactive session provides a hands-on approach to introducing ergonomics to students. Although different approaches may effectively introduce ergonomics at even early stages of development, this program was designed for youth at the middle to high school age. Attendees will participate in four activities designed to introduce ergonomics at an experiential level. The modules focus on grip strength, effective breathing, optimizing your chair, and backpack safety. The workshop will include presentation and worksheets designed for use by teachers with minimal ergonomics training. Feedback from the participants will be sought for further refining the usability and safety of the training package.
Date: February 22, 2006
Creator: Bennett, C; Alexandre, M & Jacobs, K
System: The UNT Digital Library
Design and Testing of Metal and Silicon Heat Spreaders with Embedded Micromachined Heat Pipes (open access)

Design and Testing of Metal and Silicon Heat Spreaders with Embedded Micromachined Heat Pipes

The authors have developed a new type of heat spreader based on the integration of heat pipes directly within a thin planar structure suitable for use as a heat spreader or as the base layer in a substrate. The process uses micromachining methods to produce micron scale patterns that act as a wick in these small scale heat pipes. By using silicon or a low expansion metal as the wall material of these spreaders, they achieve a good match to the thermal coefficient of expansion of the die. The match allows the use of a thin high performance die attachment even on large size die. The embedded heat pipes result in high effective thermal conductivity for the new spreader technology.
Date: February 22, 1999
Creator: Benson, D. A. & Robino, C. V.
System: The UNT Digital Library
Environmental Measurement-While-Drilling System for Real-Time Field Screening of Contaminants (open access)

Environmental Measurement-While-Drilling System for Real-Time Field Screening of Contaminants

Sampling during environmental drilling is essential to fully characterize the spatial distribution and migration of near surface contaminants. However, analysis of the samples is expensive and time-consuming: off-site laboratory analysis can take weeks or months. An alternative screening technology, Environmental Measurement-While-Drilling (EMWD), could save money and valuable time by quickly distinguishing between contaminated and uncontaminated areas. Real time measurements provided by an EMWD system enable on-the-spot decisions to be made regarding sampling strategies. The system also enhances worker safety and provides the added flexibility of being able to steer a drill bit in or out of hazardous zones.
Date: February 22, 1999
Creator: Bishop, L. B.; Lockwood, G. J.; Normann, R. A.; Selph, M. M. & Williams, C. V.
System: The UNT Digital Library
Effect of salt identity on the phase diagram for a globularprotein in aqueous electrolyte solution (open access)

Effect of salt identity on the phase diagram for a globularprotein in aqueous electrolyte solution

Monte Carlo simulations are used to establish the potential of mean force between two globular proteins in an aqueous electrolyte solution. This potential includes nonelectrostatic contributions arising from dispersion forces first, between the globular proteins, and second, between ions in solution and between each ion and the globular protein. These latter contributions are missing from standard models. The potential of mean force, obtained from simulation, is fitted to an analytic equation. Using our analytic potential of mean force and Barker-Henderson perturbation theory, we obtain phase diagrams for lysozyme solutions that include stable and metastable fluid-fluid and solid-fluid phases when the electrolyte is 0.2 M NaSCN or NaI or NaCl. The nature of the electrolyte has a significant effect on the phase diagram.
Date: February 22, 2006
Creator: Bostrom, Mathias; Tavares, Frederico W.; Ninham, Barry W. & Prausnitz, John M.
System: The UNT Digital Library
Developing models for simulation of pinched-beam dynamics in heavy ion fusion. Revision 1 (open access)

Developing models for simulation of pinched-beam dynamics in heavy ion fusion. Revision 1

For heavy-ion fusion energy applications, Mark and Yu have derived hydrodynamic models for numerical simulation of energetic pinched-beams including self-pinches and external-current pinches. These pinched-beams are applicable to beam propagation in fusion chambers and to the US High Temperature Experiment. The closure of the Mark-Yu model is obtained with adiabatic assumptions mathematically analogous to those of Chew, Goldberger, and Low for MHD. Features of this hydrodynamic beam model are compared with a kinetic treatment.
Date: February 22, 1984
Creator: Boyd, J. K.; Mark, J. W. K.; Sharp, W. M. & Yu, S. S.
System: The UNT Digital Library
Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles (open access)

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIR-SFG spectra analysis revealed that a pyridinium cation (C{sub 5}H{sub 5}NH{sup +}) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C{sub 5}H{sub 5}NH{sup +} cation becomes more hydrogen bound with the increase of the temperature. In addition, the surface coverage of the cation decreases with the increase of the temperature. An important contribution of this study is the in situ identification of reaction intermediates adsorbed on the Pt nanoparticle monolayer during pyridine hydrogenation.
Date: February 22, 2008
Creator: Bratlie, Kaitlin M.; Komvopoulos, Kyriakos & Somorjai, Gabor A.
System: The UNT Digital Library
Longitudinal beam dynamics for heavy ion fusion using WARPrz (open access)

Longitudinal beam dynamics for heavy ion fusion using WARPrz

WARPrz is a 2.5 dimensional, cylindrically symmetric, electrostatic, particle-in-cell code. It is part of the WARP family of codes which has been developed to study heavy ion fusion driver issues. WARPrz is being used to study the longitudinal dynamics of heavy ion beams including a longitudinal instability that is driven by the impedance of the LINAC accelerating modules. This instability is of concern because it can enhance longitudinal momentum spread; chromatic abhoration in the lens system restricts the amount of momentum spread allowed in the beam in the final focusing system. The impedance of the modules is modeled by a continuum of resistors and capacitors in parallel in WARPrz. We discuss simulations of this instability including the effect of finite temperature and reflection of perturbations off the beam ends. We also discuss intermittency of axial confining fields (``ears`` fields) as a seed for this instability.
Date: February 22, 1993
Creator: Callahan, D. A.; Langdon, A. B.; Friedman, A. & Haber, I.
System: The UNT Digital Library
Modeling the Longitudinal Wall Impedance Instability in Heavy Ion Beams Using an R-Z PIC Code (open access)

Modeling the Longitudinal Wall Impedance Instability in Heavy Ion Beams Using an R-Z PIC Code

The effects of the longitudinal wall impedance instability in a heavy ion beam are of great interest for heavy ion fusion drivers. We are studying this instability using the R-Z thread of the WARP PIC code. We describe the code and our model of the impedance due to the accelerating modules of the induction LINAC as a resistive wall. We present computer simulations which illustrate this instability. 2 refs., 2 figs., 1 tab.
Date: February 22, 1991
Creator: Callahan, D. A.; Langdon, A. B.; Friedman, A.; Grote, D. P. & Haber, I.
System: The UNT Digital Library
Internal wave signal processing: A model-based approach (open access)

Internal wave signal processing: A model-based approach

A model-based approach is proposed to solve the oceanic internal wave signal processing problem that is based on state-space representations of the normal-mode vertical velocity and plane wave horizontal velocity propagation models. It is shown that these representations can be utilized to spatially propagate the modal (depth) vertical velocity functions given the basic parameters (wave numbers, Brunt-Vaisala frequency profile etc.) developed from the solution of the associated boundary value problem as well as the horizontal velocity components. These models are then generalized to the stochastic case where an approximate Gauss-Markov theory applies. The resulting Gauss-Markov representation, in principle, allows the inclusion of stochastic phenomena such as noise and modeling errors in a consistent manner. Based on this framework, investigations are made of model-based solutions to the signal enhancement problem for internal waves. In particular, a processor is designed that allows in situ recursive estimation of the required velocity functions. Finally, it is shown that the associated residual or so-called innovation sequence that ensues from the recursive nature of this formulation can be employed to monitor the model`s fit to the data.
Date: February 22, 1995
Creator: Candy, J. V. & Chambers, D. H.
System: The UNT Digital Library
Innovative Confinement Concepts Workshop 2000 (Book ofAbstracts) (open access)

Innovative Confinement Concepts Workshop 2000 (Book ofAbstracts)

None
Date: February 22, 2000
Creator: Celata, Christine & Staff, Accelerator and Fusion Research
System: The UNT Digital Library
CgWind: A high-order accurate simulation tool for wind turbines and wind farms (open access)

CgWind: A high-order accurate simulation tool for wind turbines and wind farms

CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.
Date: February 22, 2010
Creator: Chand, K K; Henshaw, W D; Lundquist, K A & Singer, M A
System: The UNT Digital Library
Review of issues relevant to acceptable risk criteria for nuclear waste management (open access)

Review of issues relevant to acceptable risk criteria for nuclear waste management

Development of acceptable risk criteria for nuclear waste management requires the translation of publicly determined goals and objectives into definitive issues which, in turn, require resolution. Since these issues are largely of a subjective nature, they cannot be resolved by technological methods. Development of acceptable risk criteria might best be accomplished by application of a systematic methodology for the optimal implementation of subjective values. Multi-attribute decision analysis is well suited for this purpose.
Date: February 22, 1978
Creator: Cohen, J.J.
System: The UNT Digital Library
WIPP Waste Characterization: Implementing Regulatory Requirements in the Real World (open access)

WIPP Waste Characterization: Implementing Regulatory Requirements in the Real World

It is imperative to ensure compliance of the Waste Isolation Pilot Project (WIPP) with applicable statutory and regulatory requirements. In particular, compliance with the waste characterization requirements of the Resource Conservation and Recovery Act (RCRA) and its implementing regulation found at 40 CFR Parts 262,264 and 265 for hazardous and mixed wastes, as well as those of the Atomic Energy Act of 1954, as amended, the Reorganization Plan No. 3 of 1970, the Nuclear Waste Policy Act of 1982, as amended, and the WIPP Land Withdrawal Act, as amended, and their implementing regulations found at 40 CFR Parts 191 and 194 for non-mixed radioactive wastes, are often difficult to ensure at the operational level. For example, where a regulation may limit a waste to a certain concentration, this concentration may be difficult to measure. For example, does the definition of transuranic waste (TRU) as 100 nCi/grain of alpha-emitting transuranic isotopes per gram of waste mean that the radioassay of a waste must show a reading of 100 plus the sampling and measurement error for the waste to be a TRU waste? Although the use of acceptable knowledge to characterize waste is authorized by statute, regulation and DOE Orders, its implementation …
Date: February 22, 1999
Creator: Cooper Wayman, J.D. & Goldstein, J.D.
System: The UNT Digital Library
Testing of a refuelable zinc/air bus battery (open access)

Testing of a refuelable zinc/air bus battery

We report tests of a refuelable zinc/air battery of modular, bipolar-cell design, intended for fleet electric busses and vans. The stack consists of twelve 250-cm{sup 2} cells built of two units: (1) a copper-clad glass-reinforced epoxy board supporting anode and cathode current collectors, and (2) polymer frame providing for air- and electrolyte distribution and zinc fuel storage. The stack was refueled in 4 min. by a hydraulic transfer of zinc particles entrained in solution flow.
Date: February 22, 1995
Creator: Cooper, J. F.; Fleming, D.; Koopman, R.; Hargrove, D.; Maimoni, A. & Peterman, K.
System: The UNT Digital Library
Development of a bipolar cell for electrochemical production of lithium (open access)

Development of a bipolar cell for electrochemical production of lithium

Lithium metal can be electrolytically refined from aqueous solutions of its compounds by partial reduction to form a lithium amalgam, followed by reduction of the amalgam to liquid lithium in a molten salt cell at 225 C. A bipolar cell (with a continuous, amalgam electrode circulating between the aqueous and salt cells) was designed, constructed and successfully tested on the bench scale, as a proof of principle of an efficient, safe and low-temperature alternative to existing processes.
Date: February 22, 1995
Creator: Cooper, J.F.; Mack, G.; Peterman, K.; Weinland, S. & McKenzie, P.
System: The UNT Digital Library
Text and Structural Data Mining of Influenza Mentions in Web and Social Media (open access)

Text and Structural Data Mining of Influenza Mentions in Web and Social Media

This article discusses text and structural data mining of influenza mentions in web and social media.
Date: February 22, 2010
Creator: Corley, Courtney; Cook, Diane J., 1963-; Mikler, Armin R. & Singh, Karan P.
System: The UNT Digital Library