Absence of Debye Sheaths Due to Secondary Electron Emission (open access)

Absence of Debye Sheaths Due to Secondary Electron Emission

A bounded plasma where the hot electrons impacting the walls produce more than one secondary on average is studied via particle-in-cell simulation. It is found that no classical Debye sheath or space-charge limited sheath exists. Ions are not drawn to the walls and electrons are not repelled. Hence the unconfined plasma electrons travel unobstructed to the walls, causing extreme particle and energy fluxes. Each wall has a positive charge, forming a small potential barrier or "inverse sheath" that pulls some secondaries back to the wall to maintain the zero current condition.
Date: May 11, 2012
Creator: Campanell, M. D.; Khabrov, A. & Kaganovich, I. D.
Object Type: Report
System: The UNT Digital Library
2012 Aspen Winter Conferences on High Energy and Astrophysics (open access)

2012 Aspen Winter Conferences on High Energy and Astrophysics

Aspen Center for Physics Project Summary DE-SC0007313 Budget Period: 1/1/2012 to 12/31/2012 The Hunt for New Particles, from the Alps to the Plains to the Rockies The 2012 Aspen Winter Conference on Particle Physics was held at the Aspen Center for Physics from February 11 to February 17, 2012. Sixty-seven participants from nine countries, and several universities and national labs attended the workshop titled, The Hunt for New Particles, from the Alps to the Plains to the Rockies. There were 53 formal talks, and a considerable number of informal discussions held during the week. The weeks events included a public lecture-Hunting the Dark Universe given by Neal Weiner from New York University) and attended by 237 members of the public, and a physics cafe geared for high schoolers that is a discussion with physicists conducted by Spencer Chang (University of Oregon), Matthew Reece (Harvard University) and Julia Shelton (Yale University) and attended by 67 locals and visitors. While there were no published proceedings, some of the talks are posted online and can be Googled. The workshop was organized by John Campbell (Fermilab), Patrick Fox (Fermilab), Ivan Furic (University of Florida), Eva Halkiadakis (Rutgers University) and Daniel Whiteson (University of California …
Date: May 1, 2012
Creator: Campbell, John; Olivier, Dore; Fox, Patrick; Furic, Ivan; Halkiadakis, Eva; Schmidt, Fabian et al.
Object Type: Report
System: The UNT Digital Library
Uranium Enrichment Standards of the Y-12 Nuclear Detection and Sensor Testing Center (open access)

Uranium Enrichment Standards of the Y-12 Nuclear Detection and Sensor Testing Center

The Y-12 National Security Complex has recently fabricated and characterized a new series of metallic uranium standards for use in the Nuclear Detection and Sensor Testing Center (NDSTC). Ten uranium metal disks with enrichments varying from 0.2 to 93.2% {sup 235}U were designed to provide researchers access to a wide variety of measurement scenarios in a single testing venue. Special care was taken in the selection of the enrichments in order to closely bracket the definitions of reactor fuel at 4% {sup 235}U and that of highly enriched uranium (HEU) at 20% {sup 235}U. Each standard is well characterized using analytical chemistry as well as a series of gamma-ray spectrometry measurements. Gamma-ray spectra of these standards are being archived in a reference library for use by customers of the NDSTC. A software database tool has been created that allows for easier access and comparison of various spectra. Information provided through the database includes: raw count data (including background spectra), regions of interest (ROIs), and full width half maximum calculations. Input is being sought from the user community on future needs including enhancements to the spectral database and additional Uranium standards, shielding configurations and detector types. A related presentation are planned …
Date: May 23, 2012
Creator: Cantrell, J.
Object Type: Article
System: The UNT Digital Library

Path to Zero: Ultra-Efficient Architecture on the NREL Campus: S&TF and Master Planning

Describe the aspects of NREL's S and TF and Campus Master Planning in terms of how they have influenced ultra-efficient architecture on NREL's campus. Energy goals for the NREL campus are: (1) Understand how buildings uses energy, implement the cost-effective energy and water efficiency retrofits; (2) Use principals of energy efficiency and low energy design to reduce energy demand in all new construction; (3) Operate central plants efficiently; (4) Alternative transportation; (5) Use combined heat and power systems; (6) Use on-site renewables for demonstration and where it is cost-effective; and (7) Buy green power (over the next 25 years) so that 100% of our power will be from renewable sources.
Date: May 1, 2012
Creator: Carlisle, N.
Object Type: Presentation
System: The UNT Digital Library
Multiple Scattering Measurements in the MICE Experiment (open access)

Multiple Scattering Measurements in the MICE Experiment

The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with an accuracy of 1% by measuring muons individually. Step IV of MICE will make the first precise emittance-reduction measurements of the experiment. Simulation studies using G4MICE, based on GEANT4, find a significant difference in multiple scattering in low Z materials, compared with the standard expression quoted by the Particle Data Group. Direct measurement of multiple scattering using the scintillating-fibre trackers is found to be possible, but requires the measurement resolution to be unfolded from the data.
Date: May 1, 2012
Creator: Carlisle, T.; Cobb, J. & Neuffer, D.
Object Type: Article
System: The UNT Digital Library
Dry Transfer Systems for Used Nuclear Fuel (open access)

Dry Transfer Systems for Used Nuclear Fuel

The potential need for a dry transfer system (DTS) to enable retrieval of used nuclear fuel (UNF) for inspection or repackaging will increase as the duration and quantity of fuel in dry storage increases. This report explores the uses for a DTS, identifies associated general functional requirements, and reviews existing and proposed systems that currently perform dry fuel transfers. The focus of this paper is on the need for a DTS to enable transfer of bare fuel assemblies. Dry transfer systems for UNF canisters are currently available and in use for transferring loaded canisters between the drying station and storage and transportation casks.
Date: May 1, 2012
Creator: Carlsen, Brett W. & BradyRaap, Michaele
Object Type: Report
System: The UNT Digital Library
Temperature and Burnup Correlated FCCI in U-10Zr Metallic Fuel (open access)

Temperature and Burnup Correlated FCCI in U-10Zr Metallic Fuel

Metallic fuels are proposed for use in advanced sodium cooled fast reactors. The experience basis for metallic fuels is extensive and includes development and qualification of fuels for the Experimental Breeder Reactor I, the Experimental Breeder Reactor II, FERMI-I, and the Fast Flux Test Facility (FFTF) reactors. Metallic fuels provide a number of advantages over other fuel types in terms of fabricability, performance, recyclability, and safety. Key to the performance of all nuclear fuel systems is the resistance to “breach” and subsequent release of fission products and fuel constituents to the primary coolant system of the nuclear power plant. In metallic fuel, the experience is that significant fuel-cladding chemical (FCCI) interaction occurs and becomes prevalent at high power-high temperature operation and ultimately leads to fuel pin breach and failure. Empirical relationships for metallic fuel pin failure have been developed from a large body of in-pile and out of pile research, development, and experimentation. It has been found that significant in-pile acceleration of the FCCI rate is experienced over similar condition out-of-pile experiments. The study of FCCI in metallic fuels has led to the quantification of in-pile failure rates to establish an empirical time and temperature dependent failure limit for fuel …
Date: May 1, 2012
Creator: Carmack, William J.
Object Type: Report
System: The UNT Digital Library
Beam Loss Due to Misalignments, RF Jitter and Mismatch in the Fermilab Project-X 3GeV CW Linac (open access)

Beam Loss Due to Misalignments, RF Jitter and Mismatch in the Fermilab Project-X 3GeV CW Linac

This paper presents an analysis of beam losses along the current design of the FNAL GeV Superconducting CW Linac. Simulations from the RFQ exit up to the end of the linac (~440 meters) are performed using the beam dynamics codes TRACK and TRACEWIN. The impact of beam mismatch, element misalignments and RF jitter on the beam dynamics is discussed and corresponding beam loss patterns are presented. A correlation scheme to compensate for misalignments is described.
Date: May 1, 2012
Creator: Carneiro, J. P.; Lebedev, V. A.; Nagaitsev, S.; Ostiguy, J. F.; Saini, A.; Shteynas, B. G. et al.
Object Type: Article
System: The UNT Digital Library
CDP - Adaptive Supervisory Control and Data Acquisition (SCADA) Technology for Infrastructure Protection (open access)

CDP - Adaptive Supervisory Control and Data Acquisition (SCADA) Technology for Infrastructure Protection

Supervisory Control and Data Acquisition (SCADA) Systems are a type of Industrial Control System characterized by the centralized (or hierarchical) monitoring and control of geographically dispersed assets. SCADA systems combine acquisition and network components to provide data gathering, transmission, and visualization for centralized monitoring and control. However these integrated capabilities, especially when built over legacy systems and protocols, generally result in vulnerabilities that can be exploited by attackers, with potentially disastrous consequences. Our research project proposal was to investigate new approaches for secure and survivable SCADA systems. In particular, we were interested in the resilience and adaptability of large-scale mission-critical monitoring and control infrastructures. Our research proposal was divided in two main tasks. The first task was centered on the design and investigation of algorithms for survivable SCADA systems and a prototype framework demonstration. The second task was centered on the characterization and demonstration of the proposed approach in illustrative scenarios (simulated or emulated).
Date: May 14, 2012
Creator: Carvalho, Marco & Ford, Richard
Object Type: Report
System: The UNT Digital Library
Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance (open access)

Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

The aim of the present thesis is to investigate the local magnetic properties of homometallic Cr{sub 8} antiferromagnetic (AFM) ring and the changes occurring by replacing one Cr{sup 3+} ion with diamagnetic Cd{sup 2+} (Cr{sub 7}Cd) and with Ni{sup 2+} (Cr{sub 7}Ni). In the heterometallic ring a redistribution of the local magnetic moment is expected in the low temperature ground state. We have investigated those changes by both {sup 53}Cr-NMR and {sup 19}F-NMR. We have determined the order of magnitude of the transferred hyperfine coupling constant {sup 19}F - M{sup +} where M{sup +} = Cr{sup 3+}, Ni{sup 2+} in the different rings. This latter result gives useful information about the overlapping of the electronic wavefunctions involved in the coordinative bond.
Date: May 9, 2012
Creator: Casadei, Cecilia
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Iron-Nitride Alloy Magnets (open access)

Iron-Nitride Alloy Magnets

Advanced Research Projects Agency-Energy project sheet summarizing general information about the Rare Earth Alternatives in Critical Technologies (REACT) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses the development of a magnetic iron-nitride alloy as part of the "Transformation Enabled Nitride Magnets Absent Rare Earths (TEN Mare)" project.
Date: May 25, 2012
Creator: Case Western Reserve University
Object Type: Text
System: The UNT Digital Library
Preliminary Investigation of Zircaloy-4 as a Research Reactor Cladding Material (open access)

Preliminary Investigation of Zircaloy-4 as a Research Reactor Cladding Material

As part of a scoping study for the ATR fuel conversion project, an initial comparison of the material properties of Zircaloy-4 and Aluminum-6061 (T6 and O-temper) is performed to provide a preliminary evaluation of Zircaloy-4 for possible inclusion as a candidate cladding material for ATR fuel elements. The current fuel design for the ATR uses Aluminum 6061 (T6 and O temper) as a cladding and structural material in the fuel element and to date, no fuel failures have been reported. Based on this successful and longstanding operating history, Zircaloy-4 properties will be evaluated against the material properties for aluminum-6061. The preliminary investigation will focus on a comparison of density, oxidation rates, water chemistry requirements, mechanical properties, thermal properties, and neutronic properties.
Date: May 1, 2012
Creator: Castle, Brian K
Object Type: Report
System: The UNT Digital Library
FY12 annual Report: PHEV Engine Control and Energy Management Strategy (open access)

FY12 annual Report: PHEV Engine Control and Energy Management Strategy

The objectives are: (1) Investigate novel engine control strategies targeted at rapid engine/catalyst warming for the purpose of mitigating tailpipe emissions from plug-in hybrid electric vehicles (PHEV) exposed to multiple engine cold start events; (2) Optimize integration of engine control strategies with hybrid supervisory control strategies in order to reduce cold start emissions and fuel consumption of PHEVs; and (3) Ensure that development of new vehicle technologies complies with existing emission standards.
Date: May 1, 2012
Creator: Chambon, Paul H.
Object Type: Report
System: The UNT Digital Library
Affordable Energy-Efficient New Housing Solutions (open access)

Affordable Energy-Efficient New Housing Solutions

Since 2010, the U.S. Department of Energy’s Building America has sponsored research at PNNL to investigate cost-effective, energy-saving home-building technologies and to demonstrate how high-performance homes can deliver lower utility bills, increased comfort, and improved indoor air quality, while maintaining accessibility for low-income homeowners. PNNL and its contractors have been investigating 1) cost-effective whole-house solutions for Habitat for Humanity International (HFHI) and specific HFH affiliates in hot-humid and marine climates; 2) cost-effective energy-efficiency improvements for heating, ventilation, and air-conditioning (HVAC) systems in new, stick-built and manufactured homes; and 3) energy-efficient domestic hot-water systems.
Date: May 2012
Creator: Chandra, Subrato; Widder, Sarah H.; Bartlett, Rosemarie; McIlvaine, Janet; Chasar, David; Beal, David et al.
Object Type: Report
System: The UNT Digital Library
Tailoring properties of carbon-nanotube-based foams by ion bombardment (open access)

Tailoring properties of carbon-nanotube-based foams by ion bombardment

None
Date: May 17, 2012
Creator: Charnvanichborikarn, S.; Shin, S. J.; Worsley, M. A. & Kucheyev, S. O.
Object Type: Article
System: The UNT Digital Library
Characterization of Nb3Sn Strand for ITER (open access)

Characterization of Nb3Sn Strand for ITER

We have an ongoing research program for characterization of superconductor composite strands, the principal output of which is sensitive measurements of critical current Ic over a broad range of the essential parameters: longitudinal strain ε, temperature T, and magnetic field B. This features a new apparatus for integrated measurement of Ic(ε,T,B) on the same, long-conductor sample without remounting.
Date: May 3, 2012
Creator: Cheggour, Najib & Goodrich, Loren F.
Object Type: Report
System: The UNT Digital Library
Precision Measurement of Electroproduction of pi{sup 0} near Threshold (open access)

Precision Measurement of Electroproduction of pi{sup 0} near Threshold

Electromagnetic production of neutral pions near threshold is the most basic, lowest energy reaction in which a new hadron is created. The electromagnetic interaction is well understood so measurements of this reaction can yield direct insight into the hadronic production mechanism. During the past three decades there have been many developments in both the measurement and theory of threshold pion production, starting with measurements of photo-production at Saclay in 1986 and at Mainz in 1990. These measurements indicated a surprising discrepancy with so-called Low Energy Theorems (LETs) which are based on quite fundamental symmetries and considerations. Chiral Perturbation Theory (ChPT) is an e#11;ective #12;eld theoretic description of the nuclear force which contains the underlying symmetries of the force but deals with nucleons and pions rather than quarks and gluons. It has the advantage of being applicable at low energies but requires tuning some parameters to experimental data. Once these parameters have been determined ChPT predicts how the reaction should behave as a function of the kinematic variable. When applied to the reaction, p({gamma},{pi}{sup 0})p, near threshold it explained the discrepancy with the LETs and made predictions for electroproduction, p(e,e'p){pi}#25;{sup 0}. Electroproduction measurements at Mainz in the 1990's showed a clear …
Date: May 1, 2012
Creator: Chirapatpimol, Khem
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Understanding Nitrogen Fixation (open access)

Understanding Nitrogen Fixation

The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution …
Date: May 25, 2012
Creator: Chirik, Paul J.
Object Type: Report
System: The UNT Digital Library
Quench Performance and Field Quality of 90-mm Nb3Sn Quadrupoles of TQC Series (open access)

Quench Performance and Field Quality of 90-mm Nb3Sn Quadrupoles of TQC Series

None
Date: May 1, 2012
Creator: Chlachidze, G.; Andreev, N.; Bossert, R.; DiMarco, J.; Kashikhin, V.V.; Lamm, M.J. et al.
Object Type: Article
System: The UNT Digital Library
Impact Of Melter Internal Design On Off-Gas Flammability (open access)

Impact Of Melter Internal Design On Off-Gas Flammability

The purpose of this study was to: (1) identify the more dominant design parameters that can serve as the quantitative measure of how prototypic a given melter is, (2) run the existing DWPF models to simulate the data collected using both DWPF and non-DWPF melter configurations, (3) confirm the validity of the selected design parameters by determining if the agreement between the model predictions and data is reasonably good in light of the design and operating conditions employed in each data set, and (4) run Computational Fluid Dynamics (CFD) simulations to gain new insights into how fluid mixing is affected by the configuration of melter internals and to further apply the new insights to explaining, for example, why the agreement is not good.
Date: May 30, 2012
Creator: Choi, A. S. & Lee, S. Y.
Object Type: Report
System: The UNT Digital Library
Hazard Classification of the Remote Handled Low-Level Waste Disposal Facility (open access)

Hazard Classification of the Remote Handled Low-Level Waste Disposal Facility

The Battelle Energy Alliance (BEA) at the Idaho National Laboratory (INL) is constructing a new facility to replace remote-handled low-level radioactive waste disposal capability for INL and Naval Reactors Facility operations. Current disposal capability at the Radioactive Waste Management Complex (RWMC) will continue until the facility is full or closed for remediation (estimated at approximately fiscal year 2015). Development of a new onsite disposal facility is the highest ranked alternative and will provide RH-LLW disposal capability and will ensure continuity of operations that generate RH-LLW for the foreseeable future. As a part of establishing a safety basis for facility operations, the facility will be categorized according to DOE-STD-1027-92. This classification is important in determining the scope of analyses performed in the safety basis and will also dictate operational requirements of the completed facility. This paper discusses the issues affecting hazard classification in this nuclear facility and impacts of the final hazard categorization.
Date: May 1, 2012
Creator: Christensen, Boyd D.
Object Type: Article
System: The UNT Digital Library
10 CFR 830 Major Modification Determination for Advanced Test Reactor LEU Fuel Conversion (open access)

10 CFR 830 Major Modification Determination for Advanced Test Reactor LEU Fuel Conversion

The Advanced Test Reactor (ATR), located in the ATR Complex of the Idaho National Laboratory (INL), was constructed in the 1960s for the purpose of irradiating reactor fuels and materials. Other irradiation services, such as radioisotope production, are also performed at ATR. The ATR is fueled with high-enriched uranium (HEU) matrix (UAlx) in an aluminum sandwich plate cladding. The National Nuclear Security Administration Global Threat Reduction Initiative (GTRI) strategic mission includes efforts to reduce and protect vulnerable nuclear and radiological material at civilian sites around the world. Converting research reactors from using HEU to low-enriched uranium (LEU) was originally started in 1978 as the Reduced Enrichment for Research and Test Reactors (RERTR) Program under the U.S. Department of Energy (DOE) Office of Science. Within this strategic mission, GTRI has three goals that provide a comprehensive approach to achieving this mission: The first goal, the driver for the modification that is the subject of this determination, is to convert research reactors from using HEU to LEU. Thus the mission of the ATR LEU Fuel Conversion Project is to convert the ATR and Advanced Test Reactor Critical facility (ATRC) (two of the six U.S. High-Performance Research Reactors [HPRR]) to LEU fuel by …
Date: May 1, 2012
Creator: Christensen, Boyd D.; Lehto, Michael A. & Duckwitz, Noel R.
Object Type: Report
System: The UNT Digital Library
Biofuels from Sorghum (open access)

Biofuels from Sorghum

Advanced Research Projects Agency-Energy project sheet summarizing general information about the Plants Engineered to Replace Oil (PETRO) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses the bioengineering of sorghum plants as part of the "Plant-based Sesquiterpene Biofuels" project.
Date: May 21, 2012
Creator: Chromatin, Inc.
Object Type: Text
System: The UNT Digital Library
Longitudinal Phase Space Measurement for the Advanced Superconducting Test Accelerator Photoinjector (open access)

Longitudinal Phase Space Measurement for the Advanced Superconducting Test Accelerator Photoinjector

None
Date: May 1, 2012
Creator: Church, M. D.; Sun, Y. E.; /Fermilab; Piot, P.; /Fermilab; Prokop, C. R. et al.
Object Type: Article
System: The UNT Digital Library