Multiscale Mathematics for Biomass Conversion to Renewable Hydrogen (open access)

Multiscale Mathematics for Biomass Conversion to Renewable Hydrogen

The main focus during the period of research at UTK was on developing a mathematically rigorous and at the same time computationally flexible framework for parallelization of Kinetic Monte Carlo methods, and its implementation on multi-core architectures. Another direction of research aimed towards spatial multilevel coarse graining methods for Monte Carlo sampling and molecular simulation. The underlying theme of both of this topics was the development of numerical methods that lead to efficient and reliable simulations supported by error analysis of involved approximation schemes for coarse observables of the simulated molecular system. The work on both of these topics resulted in publications.
Date: August 31, 2010
Creator: Plechac, Petr
Object Type: Report
System: The UNT Digital Library
Field Quality of the First LARP Nb{sub 3}Sn 3.7 m-Long Quadrupole Model of LQ Series (open access)

Field Quality of the First LARP Nb{sub 3}Sn 3.7 m-Long Quadrupole Model of LQ Series

The US-LHC accelerator research program (LARP) built and tested the first 3.7-m long Nb{sub 3}Sn quadrupole model of LQ series with a 90 mm bore diameter and a target field gradient of 200 T/m. The LQ series, developed in collaboration among FNAL, LBNL and BNL, is a scale up of the previously tested 1-m long technology quadrupoles of TQ series based on similar coils and two different mechanical structures (shell-based TQS and collar-based TQC), with a primary goal of demonstrating the Nb{sub 3}Sn accelerator magnet technology for the luminosity upgrade of LHC interaction regions. In this paper, we present the field quality measurements in the first 3.7-m long LQS01 model based on the modified TQS mechanical structure. The results are compared to the expectations from the magnet geometry and magnetic properties of coils and iron yoke. Moreover, we present a comparison between this magnet and the short models previously measured.
Date: August 1, 2010
Creator: Velev, G.V.; Ambrosio, G.; Andreev, N.; Anerella, M.; Bossert, R.; Caspi, S. et al.
Object Type: Article
System: The UNT Digital Library
Introduction of Nonlinear Properties Into Hierachical Models of Nb3Sn Strands (open access)

Introduction of Nonlinear Properties Into Hierachical Models of Nb3Sn Strands

The development of computational models representing Rutherford cable formation and deformation is necessary to investigate the strain state in the superconducting filaments in Nb{sub 3}Sn magnets. The wide variety of length scales within accelerator magnets suggests usage of a hierarchical structure within the model. As part of an ongoing investigation at LBNL, a three-dimensional simplified nonlinear multiscale model is developed as a way to extend previous linear elastic versions. The inclusion of plasticity models into the problem formulation allows an improved representation of strand behavior compared to the linear elastic model. This formulation is applied to a single Nb{sub 3}Sn strand to find its effective properties as well as the strain state in the conductor under loading.
Date: August 1, 2010
Creator: Collins, B.; Krishnan, J.; Arbelaez, D.; Ferracin, P.; Prestemon, S. O.; Godeke, A. et al.
Object Type: Article
System: The UNT Digital Library
Hazardous Materials Verification and Limited Characterization Report on Sodium and Caustic Residuals in Materials and Fuel Complex Facilities MFC-799/799A (open access)

Hazardous Materials Verification and Limited Characterization Report on Sodium and Caustic Residuals in Materials and Fuel Complex Facilities MFC-799/799A

This report is a companion to the Facilities Condition and Hazard Assessment for Materials and Fuel Complex Sodium Processing Facilities MFC-799/799A and Nuclear Calibration Laboratory MFC-770C (referred to as the Facilities Condition and Hazards Assessment). This report specifically responds to the requirement of Section 9.2, Item 6, of the Facilities Condition and Hazards Assessment to provide an updated assessment and verification of the residual hazardous materials remaining in the Sodium Processing Facilities processing system. The hazardous materials of concern are sodium and sodium hydroxide (caustic). The information supplied in this report supports the end-point objectives identified in the Transition Plan for Multiple Facilities at the Materials and Fuels Complex, Advanced Test Reactor, Central Facilities Area, and Power Burst Facility, as well as the deactivation and decommissioning critical decision milestone 1, as specified in U.S. Department of Energy Guide 413.3-8, “Environmental Management Cleanup Projects.” Using a tailored approach and based on information obtained through a combination of process knowledge, emergency management hazardous assessment documentation, and visual inspection, this report provides sufficient detail regarding the quantity of hazardous materials for the purposes of facility transfer; it also provides that further characterization/verification of these materials is unnecessary.
Date: August 1, 2010
Creator: Mecham, Gary
Object Type: Report
System: The UNT Digital Library
Thermographic analyses of the growth of Cd1-xZnxTe single crystals (open access)

Thermographic analyses of the growth of Cd1-xZnxTe single crystals

Bulk Cd1-xZnxTe (0<x<0.1) single crystals for gamma-ray detectors are grown mainly from near-stoichiometric melts. We discuss the influence of the thermal pre-history of the melts (superheating, thermo-cycling, and cooling rate) on various physical properties based on our thermographic analyses, electrical conductivity and viscosity measurements. Increasing the Zn content causes non-monotonic dependencies in the quality of the crystals structure.
Date: August 1, 2010
Creator: Kopach, O. V.; Bolotnikov, A.; Shcherbak, Larysa P.; Fochuk, Petro M. & James, Ralph B.
Object Type: Article
System: The UNT Digital Library
Closure Report (CR) for Corrective Action Unit (CAU) 91: Area 3 U-3fi Injection Well with Errata Sheet and Certification, Revision 0 (open access)

Closure Report (CR) for Corrective Action Unit (CAU) 91: Area 3 U-3fi Injection Well with Errata Sheet and Certification, Revision 0

The closure report for CAU 91 has no Use Restriction Form or drawing/map included in the document to describe the use restricted area, however, Section 3.3.3 states that the site will be fenced and signage placed indicating the area as a Resource Conservation and Recovery Act (RCRA) Unit. The drawing that was placed in the FFACO indicating the use restricted area lists the coordinates for the RCRA Unit in Nevada State Plan Coordinates - North American Datum of 1983. In the ensuing years the reporting of coordinates has been standardized so that all coordinates are reported in the same manner, which is: NAD 27 UTM Zone 11 N, meters. This Errata Sheet updates the coordinate reporting to the currently accepted method and includes an aerial photo showing the RCRA Unit with the coordinates listed showing the use restricted area.
Date: August 10, 2010
Creator: Services, Navarro Nevada Environmental
Object Type: Report
System: The UNT Digital Library
90Sr liquid scintillation urine analysis utilizing different approaches for tracer recovery. (open access)

90Sr liquid scintillation urine analysis utilizing different approaches for tracer recovery.

90Sr is one of the isotopes most commonly produced by nuclear fission. This medium lived isotope presents serious challenges to radiation workers, the environment, and following a nuclear event, the general public. Methods of identifying this nuclide have been in existence for a number of years (e.g. Horwitz, E.P. [1], Maxwell, S.L.[2], EPA 905.0 [3]) which are time consuming, requiring a month or more for full analysis. This time frame is unacceptable in the present security environment. It is therefore important to have a dependable and rapid method for the determination of Sr. The purposes of this study are to reduce analysis time to less than half a day by utilizing a single method of radiation measurement while continuing to yield precise results. This paper presents findings on three methods that can meet this criteria; (1) stable Sr carrier, (2) 85Sr by gamma spectroscopy, and (3) 85Sr by LSC. Two methods of analyzing and calculating the 85Sr tracer recovery were investigated (gamma spectroscopy and a low energy window-Sr85LEBAB by LSC) as well as the use of two different types of Sr tracer (85Sr and stable Sr carrier). Three separate stock blank urine samples were spiked with various activity levels of …
Date: August 1, 2010
Creator: Piraner, Olga; Preston, Rose T.; Shanks, Sonoya Toyoko & Jones, Robert
Object Type: Report
System: The UNT Digital Library
Test Results of the first 3.7 m Long Nb3Sn Quadrupole by LARP and Future Plans (open access)

Test Results of the first 3.7 m Long Nb3Sn Quadrupole by LARP and Future Plans

In December 2009 during its first cold test, LQS01, the first long Nb{sub 3}Sn Quadrupole made by LARP (LHC Accelerator Research Program, a collaboration of BNL, FNAL, LBNL and SLAC), reached its target field gradient of 200 T/m. This target was set in 2005 by the US Department fo Energy, CERN and LARP, as a significant milestone toward the development of Nb{sub 3}Sn quadrupoles for possible use in LHC luminosity upgrades. LQS01 is a 90 mm aperture, 3.7 m long quadrupole using Nb{sub 3}Sn coils. The coil layout is equal to the layout used in the LARP Technological Quadrupoles (TQC and TQS models). Pre-stress and support are provided by a segmented aluminum shell pre-loaded using bladders and keys, similarly to the TQS models. After the first test the magnet was disassembled, reassembled with an optimized pre-stress, and reached 222 T/m at 4.5 K. In this paper we present the results of both tests and the next steps of the Long Quadrupole R&D.
Date: August 1, 2010
Creator: Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bingham, B.; Bocian, D. et al.
Object Type: Article
System: The UNT Digital Library
Measures of the Environmental Footprint of the Front End of the Nuclear Fuel Cycle (open access)

Measures of the Environmental Footprint of the Front End of the Nuclear Fuel Cycle

Previous estimates of environmental impacts associated with the front end of the nuclear fuel cycle have focused primarily on energy consumption and CO2 emissions. Results have varied widely. Section 2 of this report provides a summary of historical estimates. This study revises existing empirical correlations and their underlying assumptions to fit to a more complete set of existing data. This study also addresses land transformation, water withdrawals, and occupational and public health impacts associated with the processes of the front end of the once-through nuclear fuel cycle. These processes include uranium mining, milling, refining, conversion, enrichment, and fuel fabrication. Metrics are developed to allow environmental impacts to be summed across the full set of front end processes, including transportation and disposition of the resulting depleted uranium.
Date: August 1, 2010
Creator: Carlsen, Brett; Tavrides, Emily & Schneider, Erich
Object Type: Report
System: The UNT Digital Library
Construction of a Novel Tabletop X-Ray Generator (open access)

Construction of a Novel Tabletop X-Ray Generator

None
Date: August 25, 2010
Creator: Hostetter, James & /SLAC, /Louisiana State U.
Object Type: Report
System: The UNT Digital Library
SiC Power MOSFET with Improved Gate Dielectric (open access)

SiC Power MOSFET with Improved Gate Dielectric

In this STTR program, Structured Materials Industries (SMI), and Cornell University are developing novel gate oxide technology, as a critical enabler for silicon carbide (SiC) devices. SiC is a wide bandgap semiconductor material, with many unique properties. SiC devices are ideally suited for high-power, highvoltage, high-frequency, high-temperature and radiation resistant applications. The DOE has expressed interest in developing SiC devices for use in extreme environments, in high energy physics applications and in power generation. The development of transistors based on the Metal Oxide Semiconductor Field Effect Transistor (MOSFET) structure will be critical to these applications.
Date: August 23, 2010
Creator: Sbrockey, Nick M; Tompa, Gary S; Spencer, Michael G & Chandrashekhar, Chandra MVS
Object Type: Report
System: The UNT Digital Library
Competitive repair by naturally dispersed repetitive DNA during non-allelic homologous recombination (open access)

Competitive repair by naturally dispersed repetitive DNA during non-allelic homologous recombination

Genome rearrangements often result from non-allelic homologous recombination (NAHR) between repetitive DNA elements dispersed throughout the genome. Here we systematically analyze NAHR between Ty retrotransposons using a genome-wide approach that exploits unique features of Saccharomyces cerevisiae purebred and Saccharomyces cerevisiae/Saccharomyces bayanus hybrid diploids. We find that DNA double-strand breaks (DSBs) induce NAHR-dependent rearrangements using Ty elements located 12 to 48 kilobases distal to the break site. This break-distal recombination (BDR) occurs frequently, even when allelic recombination can repair the break using the homolog. Robust BDR-dependent NAHR demonstrates that sequences very distal to DSBs can effectively compete with proximal sequences for repair of the break. In addition, our analysis of NAHR partner choice between Ty repeats shows that intrachromosomal Ty partners are preferred despite the abundance of potential interchromosomal Ty partners that share higher sequence identity. This competitive advantage of intrachromosomal Tys results from the relative efficiencies of different NAHR repair pathways. Finally, NAHR generates deleterious rearrangements more frequently when DSBs occur outside rather than within a Ty repeat. These findings yield insights into mechanisms of repeat-mediated genome rearrangements associated with evolution and cancer.
Date: August 27, 2010
Creator: Hoang, Margaret L.; Tan, Frederick J.; Lai, David C.; Celniker, Sue E.; Hoskins, Roger A.; Dunham, Maitreya J. et al.
Object Type: Article
System: The UNT Digital Library
NLM Evidence-based Information at Your Fingertips - NBNA (open access)

NLM Evidence-based Information at Your Fingertips - NBNA

The workshop titled, National Library of Medicine: Evidence-based Information At Your Fingertips, is a computer training class designed to meet the needs of nurses who require access to information on specific medical topics and on the adverse health effects of exposure to hazardous substances. The Specialized Information Services Division of the National Library of Medicine (NLM) is sponsoring this workshop for the National Black Nurses Association to increase the awareness of health professionals of the availability and value of the free NLM medical, environmental health, and toxicology databases.
Date: August 6, 2010
Creator: Womble, R.
Object Type: Book
System: The UNT Digital Library
Performance of Nb3Sn Quadrupole Under High Stress (open access)

Performance of Nb3Sn Quadrupole Under High Stress

Future upgrades of the Large Hadron Collider (LHC) will require large aperture and high gradient quadrupoles. Nb{sub 3}Sn is the most viable option for this application but is also known for its strain sensitivity. In high field magnets, with magnetic fields above 12 T, the Lorentz forces will generate mechanical stresses that may exceed 200 MPa in the windings. The existing measurements of critical current versus strain of Nb{sub 3}Sn strands or cables are not easily applicable to magnets. In order to investigate the impact of high mechanical stress on the quench performance, a series of tests was carried out within a LBNL/CERN collaboration using the magnet TQS03 (a LHC Accelerator Research Program (LARP) 1-meter long, 90-mm aperture Nb{sub 3}Sn quadrupole). The magnet was tested four times at CERN under various pre-stress conditions. The average mechanical compressive azimuthal pre-stress on the coil at 4.2 K ranged from 120 MPa to 200 MPa. This paper reports on the magnet performance during the four tests focusing on the relation between pre-stress conditions and the training plateau.
Date: August 1, 2010
Creator: Felice, H.; Bajko, M.; Bingham, B.; Bordini, B.; Bottura, L.; Caspi, S. et al.
Object Type: Article
System: The UNT Digital Library
Numerical Investigation of the Quench Behavior of Bi2Sr2CaCu2Ox Wire (open access)

Numerical Investigation of the Quench Behavior of Bi2Sr2CaCu2Ox Wire

The quench behavior of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (Bi2212) wire is investigated through numerical simulations. This work is part of the U.S. Very High Field Superconducting Magnet Collaboration (VHFSMC). Numerical simulations are carried out using a one-dimensional computational model of thermal transport in Bi2212 composite wires. A quench is simulated by introducing heat in a section of the wire, and the voltage and temperature are monitored as function of time and position. The quench energy, normal zone propagation velocity, and spatial distribution of temperature are calculated for varying transport current and applied magnetic field. The relevance of these simulations in defining criteria for experimental measurements is discussed.
Date: August 1, 2010
Creator: Arbelaez, D.; Prestemon, S. O.; Dietderich, D. R.; Godeke, A.; Ye, L.; Hunte, F. et al.
Object Type: Article
System: The UNT Digital Library
Initiating the D&D Project for the EBR-II (open access)

Initiating the D&D Project for the EBR-II

A novel decommissioning project is underway to close the Experimental Breeder Reactor-II (EBR-II) “fast” reactor at the Idaho National Laboratory (INL), Materials and Fuels Complex (MFC) facility near Idaho Falls, ID. The facility was placed in cold shutdown in 1994 and work began on the removal of the metallic sodium coolant. The bulk of the sodium was drained and treated beginning in 2001. The residual sodium heel was chemically passivated to render it less reactive in 2005 using a novel carbon dioxide treatment. Approximately 700 kg of metallic sodium and 3500 kg of sodium bicarbonate remain in the facility. A RCRA Waste Treatment Permit, issued in 2002 by the State of Idaho Department of Environmental Quality, requires annual progress toward closure of the facility, and that all regulated materials be removed or deactivated, and the waste products removed by 2022. The baseline sodium removal technology would result in about 100,000 gallons of low-level waste solution requiring treatment along with separate handling of the large components (intermediate heat exchanger, rotating plug, etc) outside of the primary tank.
Date: August 1, 2010
Creator: Demmer, Rick
Object Type: Article
System: The UNT Digital Library
Preliminary study for the OFFELO (open access)

Preliminary study for the OFFELO

X-ray Optics-Free FEL Oscillator (OFFELO) has potential of becoming a choice for next generation light sources. Using electron beam for the feedback allows OFFELO to be completely tunable and to combine the peak power of high-gain SASE FELs with extremely narrow bandwidth of the oscillator. While the high-gain X-ray FELs has been studied in depth and has been successfully demonstrated, two other concepts (the transport and the feed-back) involved in OFFELO still need detail studies. In this short paper we focus on the simulation of the feedback process and the evolution of FEL spectrum in X-ray OFFELO. In our initial studies of OFFELO studied the saturation of the system and also its evolution using Genesis 2.0 code with a homemade wrapping code. While and lattice design from the modulator to the radiator, in order to minimize the feedback information loss in transporting the beam.
Date: August 23, 2010
Creator: Hao, Y. & Litvinenko, V. N.
Object Type: Article
System: The UNT Digital Library
R&D ERL: Magnetic measurements of the ERL magnets (open access)

R&D ERL: Magnetic measurements of the ERL magnets

The magnet system of ERL consists of G5 solenoids, 6Q12 quadrupoles with 0.58 T/m gradient, 3D60 dipoles with 0.4 T central field, 15 and 30 degree Z-bend injection line dipole/quadrupole combined function magnets, and extraction line magnets. More details about the magnets can be found in a report by G. Mahler. Field quality in all the 6Q12 quadrupoles, 3D60 dipoles and the injection line magnets has been measured with either a rotating coil, or a Hall probe mapper. This report presents the results of these magnetic measurements.
Date: August 1, 2010
Creator: Jain, A.
Object Type: Report
System: The UNT Digital Library
Compliance and Verification of Standards and Labeling Programs in China: Lessons Learned (open access)

Compliance and Verification of Standards and Labeling Programs in China: Lessons Learned

After implementing several energy efficiency standards and labels (30 products covered by MEPS, 50 products covered by voluntary labels and 19 products by mandatory labels), the China National Institute of Standardization (CNIS) is now implementing verification and compliance mechanism to ensure that the energy information of labeled products comply with the requirements of their labels. CNIS is doing so by organizing check testing on a random basis for room air-conditioners, refrigerators, motors, heaters, computer displays, ovens, and self -ballasted lamps. The purpose of the check testing is to understand the implementation of the Chinese labeling scheme and help local authorities establishing effective compliance mechanisms. In addition, to ensure robustness and consistency of testing results, CNIS has coordinated a round robin testing for room air conditioners. Eight laboratories (Chinese (6), Australian (1) and Japanese (1)) have been involved in the round robin testing and tests were performed on four sets of samples selected from manufacturer's production line. This paper describes the methodology used in undertaking both check and round robin testing, provides analysis of testing results and reports on the findings. The analysis of both check and round robin testing demonstrated the benefits of a regularized verification and monitoring system for …
Date: August 1, 2010
Creator: Saheb, Yamina; Zhou, Nan; Fridley, David & Pierrot, Andre
Object Type: Report
System: The UNT Digital Library
Kinetics of small particle activation in supersaturated vapors (open access)

Kinetics of small particle activation in supersaturated vapors

We examine the nucleated (with barrier) activation of perfectly wetting (zero contact angle) particles ranging from bulk size down to one nanometer. Thermodynamic properties of the particles, coated with liquid layers of varying thickness and surrounded by vapor, are analyzed. Nano-size particles are predicted to activate at relative humidity below the Kelvin curve on crossing a nucleation barrier, located at a critical liquid layer thickness such that the total particle size (core + liquid layer) equals the Kelvin radius (Fig. 1). This barrier vanishes precisely as the critical layer thickness approaches the thin layer limit and the Kelvin radius equals the radius of the particle itself. These considerations are similar to those included in Fletcher's theory (Fletcher, 1958) however the present analysis differs in several important respects. Firstly, where Fletcher used the classical prefactor-exponent form for the nucleation rate, requiring separate estimation of the kinetic prefactor, we solve a diffusion-drift equation that is equivalent to including the full Becker-Doering (BD) multi-state kinetics of condensation/evaporation along the growth coordinate. We also determine the mean first passage time (MFPT) for barrier crossing (Wedekind et al., 2007), which is shown to provide a generalization of BD nucleation kinetics especially useful for barrier heights …
Date: August 29, 2010
Creator: McGraw, R. & Wang, J.
Object Type: Article
System: The UNT Digital Library
Alternative Electrochemical Salt Waste Forms, Summary of FY2010 Results (open access)

Alternative Electrochemical Salt Waste Forms, Summary of FY2010 Results

In FY2009, PNNL performed scoping studies to qualify two waste form candidates, tellurite (TeO2-based) glasses and halide minerals, for the electrochemical waste stream for further investigation. Both candidates showed promise with acceptable PCT release rates and effective incorporation of the 10% fission product waste stream. Both candidates received reprisal for FY2010 and were further investigated. At the beginning of FY2010, an in-depth literature review kicked off the tellurite glasses study. The review was aimed at ascertaining the state-of-the-art for chemical durability testing and mixed chloride incorporation for tellurite glasses. The literature review led the authors to 4 unique binary and 1 unique ternary systems for further investigation which include TeO2 plus the following: PbO, Al2O3-B2O3, WO3, P2O5, and ZnO. Each system was studied with and without a mixed chloride simulated electrochemical waste stream and the literature review provided the starting points for the baseline compositions as well as starting points for melting temperature, compatible crucible types, etc. The most promising glasses in each system were scaled up in production and were analyzed with the Product Consistency Test, a chemical durability test. Baseline and PCT glasses were analyzed to determine their state, i.e., amorphous, crystalline, phase separated, had undissolved material within …
Date: August 1, 2010
Creator: Riley, Brian J.; Rieck, Bennett T.; Crum, Jarrod V.; Matyas, Josef; McCloy, John S.; Sundaram, S. K. et al.
Object Type: Report
System: The UNT Digital Library
Bench-Top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade (open access)

Bench-Top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade

Simulations have been performed in Omega3P to study both trapped modes and impedance contributions of a rotatable collimator for the LHC phase II collimation upgrade. Bench-top stretched coil probe impedance methods are also being implemented for measurements on prototype components to directly measure the low frequency impedance contributions. The collimator design also calls for a RF contact interface at both jaw ends with contact resistance much less than a milliohm in order to limit transverse impedance. DC resistance measurements in a custom built test chamber have been performed to test the performance of this interface.
Date: August 26, 2010
Creator: Smith, Jeffrey Claiborne; Bane, Karl; Doyle, Eric; Keller, Lew; Lundgren, Steve; Markiewicz, Tom et al.
Object Type: Article
System: The UNT Digital Library
Initial and Final State Interaction Effects in Small-x Quark Distributions (open access)

Initial and Final State Interaction Effects in Small-x Quark Distributions

We study the initial and final state interaction effects in the transverse momentum dependent parton distributions in the small-x saturation region. In particular, we discuss the quark distributions in the semi-inclusive deep inelastic scattering, Drell-Yan lepton pair production and dijet-correlation processes in pA collisions. We calculate the quark distributions in the scalar-QED model and then extend to the color glass condensate formalism in QCD. The quark distributions are found universal between the DIS and Drell-Yan processes. On the other hand, the quark distribution from the qq'-->qq' channel contribution to the dijet-correlation process is not universal. However, we find that it can be related to the quark distribution in DIS process by a convolution with the normalized unintegrated gluon distribution in the CGC formalism in the large Nc limit.
Date: August 30, 2010
Creator: Xiao, Bo-Wen & Yuan, Feng
Object Type: Article
System: The UNT Digital Library
Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin (open access)

Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin

Bulk samples and thin films were fabricated and characterized to determine their suitability for studying the effect of composition and morphology on strain sensitivity. Heat capacity and resistivity data are used to determine the critical temperature distribution. It is found that all bulk samples contain stoichiometric Nb{sub 3}Sn regardless of their nominal Nb to Sn ratio. Furthermore, in bulk samples with Cu additions, a bi-modal distribution of stoichiometric and off-stoichiometric Nb-Sn is found. Thus the nominally off-stoichiometric bulk samples require additional homogenization steps to yield homogeneous off-stoichiometric samples. A binary magnetron-sputtered thin film has the intended off-stoichiometric Nb-Sn phase with a mid-point critical temperature of 16.3 K. This type of sample is a suitable candidate for investigating the strain sensitivity of A15 Nb{sub 1-{beta}}Sn{sub {beta}}, with 0.18 < {beta} < 0.25. The strain sensitivity of Nb-Sn as a function of composition and morphology is important for an in-depth understanding of the strain sensitivity of composite Nb{sub 3}Sn wires.
Date: August 1, 2010
Creator: Mentink, M. G. T.; Anders, A.; Dhalle, M. M. J.; Dietderich, D. R.; Godeke, A.; Goldacker, W. et al.
Object Type: Article
System: The UNT Digital Library