Environmental Challenges for the Nuclear Diagnostics on the NIF and LMJ (open access)

Environmental Challenges for the Nuclear Diagnostics on the NIF and LMJ

The National Ignition Facility (NIF) and Laser Mega Joule (LMJ) facilities are currently under construction in the United States and France. Ignited targets at these facilities are anticipated to produce up to 1019 deuterium-tritium fusion neutrons. This will provide unprecedented opportunities and challenges for the use of nuclear diagnostics in inertial confinement fusion experiments. The NIF and LMJ nuclear diagnostics will work in a harsh radiation environment that includes neutron, hard x-ray, and gamma backgrounds, neutron induced signals in coaxial cables, and electromagnetic pulse (EMP) generated signals. Recent results of different background measurements on OMEGA laser facility will be reported. Based on these results, specific design concepts have been identified to mitigate much of the radiation and EMP-induced backgrounds. An overview of the background mitigation techniques in the NIF nuclear diagnostics conceptual designs will be presented.
Date: June 27, 2007
Creator: al., K. Miller et
Object Type: Article
System: The UNT Digital Library
Initial Study Comparing the Radiating Divertor Behavior in Single-Null and Double-Null Plasmas in DIII-D (open access)

Initial Study Comparing the Radiating Divertor Behavior in Single-Null and Double-Null Plasmas in DIII-D

'Puff and pump' radiating divertor scenarios [1,2] were applied to upper SN and DN H-mode plasmas. Under similar operating conditions, argon (Ar) accumulated in the main plasma of single-null (SN) plasmas more rapidly and reached a higher steady-state concentration when the B x {del}B ion drift direction was toward the divertor than when the B x {del}B ion drift direction was out of the divertor. The initial rate that Ar accumulated inside double-null (DN) plasmas was more than twice that of comparably-prepared SNs with the same B x {del}B direction. One way to reduce power loading at the divertor targets is to 'seed' the divertor plasma with impurities that radiatively reduce the conducted power. Studies have shown that the concentration of impurities in the divertor are increased by raising the flow of deuterium ions (D{sup +}) into the divertor by a combination of upstream deuterium gas puffing and active particle exhaust at the divertor targets, i.e., puff-and-pump. An enhanced D{sup +} particle flow toward the divertor targets exerts a frictional drag on impurities, and inhibits their escape from the divertor. A puff-and-pump approach using Ar as the impurity was successfully applied in recent DIII-D experiments to SN plasmas [3] while …
Date: June 27, 2007
Creator: Petrie, T; Brooks, N; Fenstermacher, M; Groth, M; Hyatt, A; Isler, R et al.
Object Type: Article
System: The UNT Digital Library
Computational Biology, Advanced Scientific Computing, and Emerging Computational Architectures (open access)

Computational Biology, Advanced Scientific Computing, and Emerging Computational Architectures

This CRADA was established at the start of FY02 with $200 K from IBM and matching funds from DOE to support post-doctoral fellows in collaborative research between International Business Machines and Oak Ridge National Laboratory to explore effective use of emerging petascale computational architectures for the solution of computational biology problems. 'No cost' extensions of the CRADA were negotiated with IBM for FY03 and FY04.
Date: June 27, 2007
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Coupled Reservoir-Geomechanical Analysis of the Potential for Tensile and Shear Failure Associated With CO2 Injection in Multilayered Reservoir-Caprock Systems (open access)

Coupled Reservoir-Geomechanical Analysis of the Potential for Tensile and Shear Failure Associated With CO2 Injection in Multilayered Reservoir-Caprock Systems

Coupled reservoir-geomechanical simulations were conductedto study the potential for tensile and shear failure e.g., tensilefracturing and shear slip along pre-existing fractures associated withunderground CO2 injection in a multilayered geological system. Thisfailure analysis aimed to study factors affecting the potential forbreaching a geological CO2 storage system and to study methods forestimating the maximum CO2 injection pressure that could be sustainedwithout causing such a breach. We pay special attention to geomechanicalstress changes resulting from upward migration of the CO2 and how theinitial stress regime affects the potential for inducing failure. Weconclude that it is essential to have an accurate estimate of thethree-dimensional in situ stress field to support the design andperformance assessment of a geological CO2 injection operation. Moreover,we also conclude that it is important to consider mechanical stresschanges that might occur outside the region of increased reservoir fluidpressure (e.g., in the overburden rock) between the CO2-injectionreservoir and the ground surface.
Date: March 27, 2007
Creator: Rutqvist, J.; Birkholzer, J. T. & Tsang, C.-F.
Object Type: Article
System: The UNT Digital Library
Plasma Electrode Pockels Cell Subsystem Performance in the National Ignition Facility (open access)

Plasma Electrode Pockels Cell Subsystem Performance in the National Ignition Facility

The Plasma Electrode Pockels Cell (PEPC) subsystem is a key component of the National Ignition Facility, enabling the laser to employ an efficient four-pass main amplifier architecture. PEPC relies on a pulsed power technology to initiate and maintain plasma within the cells and to provide the necessary high voltage bias to the cells nonlinear crystals. Ultimately, nearly 300 high-voltage, high-current pulse generators will be deployed in the NIF in support of PEPC. Production of solid-state plasma pulse generators and thyratron-switched pulse generators is now complete, with the majority of the hardware deployed in the facility. An entire cluster (one-fourth of a complete NIF) has been commissioned and is operating on a routine basis, supporting laser shot operations. Another cluster has been deployed, awaiting final commissioning. Activation and commissioning of new hardware continues to progress in parallel, driving toward a goal of completing the PEPC subsystem in late 2007.
Date: July 27, 2007
Creator: Barbosa, F.; Arnold, P.; Hinz, A.; Zacharias, R.; Ollis, C.; Fulkerson, E. et al.
Object Type: Article
System: The UNT Digital Library
Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines (open access)

Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines

Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5 m Czerny-Turner spectrometer. While the Balmer emission lines, Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2-n and 3-m transitions with principle quantum numbers n = 7-12 and m = 10-12 using recent Model Microfield Method calculations (C. Stehle and R. Hutcheon, Astron. Astrophys. Supl. Ser. 140, 93 (1999)). Densities in the range (5-50) x 10{sup 19} m{sup -3} are obtained in the recombining inner divertor plasma in 2-6 MW NBI H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects, and low sensitivity to instrumental and Doppler broadening. The lines are situated in the near-infrared wavelength domain, where optical signal extraction schemes for harsh nuclear environments are practically realizable, and where a recombining divertor plasma is optically thin. These properties make them an attractive recombining divertor density diagnostic for a burning plasma experiment.
Date: April 27, 2007
Creator: Soukhanovskii, V A; Johnson, D W; Kaita, R & Roquemore, A L
Object Type: Article
System: The UNT Digital Library
Research and Development of an Integral Separator for a Centrifugal Gas Processing Facility (open access)

Research and Development of an Integral Separator for a Centrifugal Gas Processing Facility

A COMPACT GAS PROCESSING DEVICE WAS INVESTIGATED TO INCREASE GAS PRODUCTION FROM REMOTE, PREVIOUSLY UN-ECONOMIC RESOURCES. THE UNIT WAS TESTED ON AIR AND WATER AND WITH NATURAL GAS AND LIQUID. RESULTS ARE REPORTED WITH RECOMMENDATIONS FOR FUTURE WORK.
Date: February 27, 2007
Creator: Hays, Lance
Object Type: Report
System: The UNT Digital Library
FRONT-END ASIC FOR A SILICON COMPTON TELESCOPE. (open access)

FRONT-END ASIC FOR A SILICON COMPTON TELESCOPE.

We describe a front-end application specific integrated circuit (ASIC) developed for a silicon Compton telescope. Composed of 32 channels, it reads out signals in both polarities from each side of a Silicon strip sensor, 2 mm thick 27 cm long, characterized by a strip capacitance of 30 pF. Each front-end channel provides low-noise charge amplification, shaping with a stabilized baseline, discrimination, and peak detection with an analog memory. The channels can process events simultaneously, and the read out is sparsified. The charge amplifier makes uses a dual-cascode configuration and dual-polarity adaptive reset, The low-hysteresis discriminator and the multi-phase peak detector process signals with a dynamic range in excess of four hundred. An equivalent noise charge (ENC) below 200 electrons was measured at 30 pF, with a slope of about 4.5 electrons/pF at a peaking time of 4 {micro}s. With a total dissipated power of 5 mW the channel covers an energy range up to 3.2 MeV.
Date: October 27, 2007
Creator: DE GERONIMO,G.; FRIED, J.; FROST, E.; PHLIPS, B.; VERNON, E. & WULF, E.A.
Object Type: Article
System: The UNT Digital Library
Monitoring the Thermal Power of Nuclear Reactors with a Prototype Cubic Meter Antineutrino Detector (open access)

Monitoring the Thermal Power of Nuclear Reactors with a Prototype Cubic Meter Antineutrino Detector

In this paper, we estimate how quickly and how precisely a reactor's operational status and thermal power can be monitored over hour to month time scales, using the antineutrino rate as measured by a cubic meter scale detector. Our results are obtained from a detector we have deployed and operated at 25 meter standoff from a reactor core. This prototype can detect a prompt reactor shutdown within five hours, and monitor relative thermal power to 3.5% within 7 days. Monitoring of short-term power changes in this way may be useful in the context of International Atomic Energy Agency's (IAEA) Reactor Safeguards Regime, or other cooperative monitoring regimes.
Date: June 27, 2007
Creator: Bernstein, A; Bowden, N; Misner, A & Palmer, T
Object Type: Article
System: The UNT Digital Library
Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac (open access)

Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac

None
Date: June 27, 2007
Creator: Molloy, S.; Adolphsen, C.; Bane, K.; Frisch, J.; Li, Z.; May, J. et al.
Object Type: Article
System: The UNT Digital Library
Watershed Restoration Project (open access)

Watershed Restoration Project

In 2003, the U.S. Department of Energy issued the Eastern Nevada Landscape Coalition (ENLC) funding to implement ecological restoration in Gleason Creek and Smith Valley Watersheds. This project was made possible by congressionally directed funding that was provided through the US Department of Energy, Energy Efficiency and Renewable Energy, Office of the Biomass Program. The Ely District Bureau of Land Management (Ely BLM) manages these watersheds and considers them priority areas within the Ely BLM district. These three entities collaborated to address the issues and concerns of Gleason Creek and Smith Valley and prepared a restoration plan to improve the watersheds’ ecological health and resiliency. The restoration process began with watershed-scale vegetation assessments and state and transition models to focus on restoration sites. Design and implementation of restoration treatments ensued and were completed in January 2007. This report describes the restoration process ENLC undertook from planning to implementation of two watersheds in semi-arid Eastern Nevada.
Date: September 27, 2007
Creator: Thompson, Julie & Macfarlan, Betsy
Object Type: Report
System: The UNT Digital Library
Radiation damage to BSCCO-2223 from 50 MEV protons. (open access)

Radiation damage to BSCCO-2223 from 50 MEV protons.

The use of HTS materials in high radiation environmentsrequires that the superconducting properties remain constant up to aradiation high dose. BSCCO-2223 samples from two manufacturers wereirradiated with 50 MeV protons at fluences of up to 5 x 1017 protons/cm2.The samples lost approximately 75 percent of their pre-irradiation Ic.This compares with Nb3Sn, which loses about 50 percent at the samedisplacements per atom.
Date: November 27, 2007
Creator: Zeller, A. F.; Ronningen, R. M.; Godeke, A.; Heilbronn, L. H.; McMahan-Norris, P. & Gupta, R.
Object Type: Article
System: The UNT Digital Library
Studies of Background Levels for the NIF Yield Diagnostics from Neutron and Gamma Radiation (open access)

Studies of Background Levels for the NIF Yield Diagnostics from Neutron and Gamma Radiation

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is nearing completion of construction and is preparing for the National Ignition Campaign (NIC) with potentially significant yield in 2010. The design of a wide range of yield diagnostics in and outside the target-bay of the NIF must consider scattered background neutrons and neutron-induced gamma rays to measure neutrons and x-rays from target. The large and complex target chamber and facility make the calculation of scattered neutrons and gamma rays extremely challenging. The NIF was designed with shielded locations for many of the yield diagnostics including the neutron alcove and four diagnostic mezzanines. Accurate calculation of the background levels in these shielded locations requires advanced Monte Carlo techniques, e.g., variance reduction. Placement, size, and materials of collimators on the line of sight (LOS) through the shielding must be evaluated to trade off signal levels and unwanted backgrounds. The background at these locations is also affected by neutrons that pass through the laser beam tubes and scatter off of structures and walls in the switch yards. Detailed 3D Monte Carlo analyses are performed to determine neutron and gamma fluxes for some of the yield diagnostics.
Date: August 27, 2007
Creator: Song, P.; Eder, D.; Moran, M.; Landen, O.; O'Brien, D. & Hsing, W.
Object Type: Article
System: The UNT Digital Library
Modeling Dynamic Ductility: An Equation of State for Porous Metals (open access)

Modeling Dynamic Ductility: An Equation of State for Porous Metals

Enhanced heating from shock compression of a porous material can potentially suppress or delay cracking of the material on subsequent expansion. In this paper we quantify the expected enhanced heating in an experiment in which a sector of a thin cylindrical shell is driven from the inside surface by SEMTEX high explosive ({approx}1 {micro}s FWHM pressure pulse with peak pressure {approx}21.5 GPa). We first derive an analytical equation of state (EOS) for porous metals, then discuss the coupling of this EOS with material elastic-plastic response in a 2D hydrocode, and then discuss the modeling of the HE experiment with both fully dense and 10% porous Ta and a Bi/Ta composite. Finally, we compare our modeling with some recent experimental data.
Date: July 27, 2007
Creator: Colvin, J
Object Type: Article
System: The UNT Digital Library
The National Ignition Facility and the Golden Age of High Energy Density Science (open access)

The National Ignition Facility and the Golden Age of High Energy Density Science

The National Ignition Facility (NIF) is a 192-beam Nd:glass laser facility being constructed at the Lawrence Livermore National Laboratory (LLNL) to conduct research in inertial confinement fusion (ICF) and high energy density (HED) science. When completed, NIF will produce 1.8 MJ, 500 TW of ultraviolet light, making it the world's largest and highest-energy laser system. The NIF is poised to become the world's preeminent facility for conducting ICF and fusion energy research and for studying matter at extreme densities and temperatures.
Date: September 27, 2007
Creator: Meier, W; Moses, E I & Newton, M
Object Type: Article
System: The UNT Digital Library
A Steinberg-Guinan model for High-Pressure Carbon, Diamond Phase (open access)

A Steinberg-Guinan model for High-Pressure Carbon, Diamond Phase

Since the carbon, diamond phase has such a high yield strength, dynamic simulations must account for strength even for strong shock waves ({approx} 3 Mbar). We have determined an initial parametrization of two strength models: Steinberg-Guinan (SG) and a modified or improved SG, that captures the high pressure dependence of the calculated shear modulus up to 10 Mbar. The models are based upon available experimental data and on calculated elastic moduli using robust density functional theory. Additionally, we have evaluated these models using hydrodynamic simulations of planar shocks experiments.
Date: July 27, 2007
Creator: Orlikowski, D.; Correa, A.; Schwegler, E. & Klepeis, J.
Object Type: Article
System: The UNT Digital Library
Plans for Ignition Experiments on NIF (open access)

Plans for Ignition Experiments on NIF

The National Ignition Facility (NIF) is a 192-beam Nd-glass laser facility presently under construction at Lawrence Livermore National Laboratory (LLNL) in support of inertial confinement fusion (ICF) and high-energy-density (HED) science. NIF will produce 1.8 MJ, 500 TW of ultraviolet light, making it the world's largest and most powerful laser system. NIF will be the world's preeminent facility for the study of matter at extreme temperatures and densities and for producing and developing ICF. The ignition studies will be the next important step in developing inertial fusion energy.
Date: July 27, 2007
Creator: Moses, Edward
Object Type: Article
System: The UNT Digital Library
The Effect of Magnetic Field on the Position of HTS Leads and theCooler in the Services Tower of the MICE Focusing Magnet (open access)

The Effect of Magnetic Field on the Position of HTS Leads and theCooler in the Services Tower of the MICE Focusing Magnet

The MICE focusing solenoids have three 4 K coolers (two forthe superconducting magnet and one for the liquid absorber) and four HTSleads that feed the current to the focusing coils. The focusing solenoidsproduce large radial external fields when they operate with the polarityof the two coils in opposition (the gradient or flip mode). When the MICEfocusing coils operate at the same polarity (the solenoid or non-flipmode), the fields are much smaller and parallel to the axis of thesolenoid. The worst-case magnetic field affects the selection of thecooler and the HTS leads. This magnetic field can also determine theheight of the service towers that house the three coolers and the fourHTS leads. This paper shows the criteria used for Cooler selection, HTSlead selection, and the position of both the cooler and leads withrespect to the solenoid axis of rotation.
Date: August 27, 2007
Creator: Green, M. A.; Yang, S. Q.; Cobb, J.; Lau, P.; Lau, W. W.; Witte, H. et al.
Object Type: Article
System: The UNT Digital Library
Local Three-Nucleon Interaction from Chiral Effective Field Theory (open access)

Local Three-Nucleon Interaction from Chiral Effective Field Theory

None
Date: April 27, 2007
Creator: Navratil, P
Object Type: Article
System: The UNT Digital Library
Laser-plasma interaction in ignition relevant plasmas: benchmarking our 3D modelling capabilities versus recent experiments (open access)

Laser-plasma interaction in ignition relevant plasmas: benchmarking our 3D modelling capabilities versus recent experiments

We have developed a new target platform to study Laser Plasma Interaction in ignition-relevant condition at the Omega laser facility (LLE/Rochester)[1]. By shooting an interaction beam along the axis of a gas-filled hohlraum heated by up to 17 kJ of heater beam energy, we were able to create a millimeter-scale underdense uniform plasma at electron temperatures above 3 keV. Extensive Thomson scattering measurements allowed us to benchmark our hydrodynamic simulations performed with HYDRA [1]. As a result of this effort, we can use with much confidence these simulations as input parameters for our LPI simulation code pF3d [2]. In this paper, we show that by using accurate hydrodynamic profiles and full three-dimensional simulations including a realistic modeling of the laser intensity pattern generated by various smoothing options, fluid LPI theory reproduces the SBS thresholds and absolute reflectivity values and the absence of measurable SRS. This good agreement was made possible by the recent increase in computing power routinely available for such simulations.
Date: September 27, 2007
Creator: Divol, L; Froula, D H; Meezan, N; Berger, R; London, R A; Michel, P et al.
Object Type: Article
System: The UNT Digital Library
SEMATECH EUV resist benchmarking results (open access)

SEMATECH EUV resist benchmarking results

Extreme Ultraviolet Lithography (EUVL) is one of the leading candidates for next generation lithography technology for the 32 nm HP and beyond. The availability of EUV resists is one of the most significant challenges facing its commercialization. To accelerate EUV resist development, SEMATECH provides access to two exposure tools: (1) The EUV Resist Test Center (RTC) at SEMATECH at the University at Albany, SUNY, NY; and (2) the SEMATECH microexposure tools (ALS-MET) at Lawrence Berkeley National Laboratory (LBNL).
Date: October 27, 2007
Creator: Ma, Andy; Park, Joo-On; Dean, Kim; Wurm, Stefan & Naulleau, Patrick
Object Type: Article
System: The UNT Digital Library
Simple but Stronger UO, Double but Weaker UNMe Bonds: The Tale Told by Cp2UO and Cp2UNR (open access)

Simple but Stronger UO, Double but Weaker UNMe Bonds: The Tale Told by Cp2UO and Cp2UNR

The free energies of reaction and the activation energies are calculated, with DFT (B3PW91) and small RECP (relativistic core potential) for uranium, for the reaction of Cp2UNMe and Cp2UO with MeCCMe and H3Si-Cl that yields the corresponding addition products. CAS(2,7) and DFT calculations on Cp2UO and Cp2UNMe give similar results, which validates the use of DFT calculations in these cases. The calculated results mirror the experimental reaction of [1,2,4-(CMe3)3C5H2]2UNMe with dimethylacetylene and [1,2,4-(CMe3)3C5H2]2UO with Me3SiCl. The net reactions are controlled by the change in free energy between the products and reactants, not by the activation energies, and therefore by the nature of the UO and UNMe bonds in the initial and final states. A NBO analysis indicates that the U-O interaction in Cp2UO is composed of a single U-O bond with three lone pairs of electrons localized on oxygen, leading to a polarized U-O fragment. In contrast, the U-NMe interaction in Cp2UNMe is composed of a and component and a lone pairof electrons localized on the nitrogen, resulting in a less polarized UNMe fragment, in accord with the lower electronegativity of NMe relative to O. The strongly polarized U(+)-O(-) bond is calculated to be about 70 kcal mol-1 stronger than …
Date: June 27, 2007
Creator: LPCNO, CNRS-UPS-INSA, INSA Toulouse; Institut Charles Gerhardt, CNRS, Universite Montpellier; Laboratoire de Chimie et Physique Quantiques, CNRS, IRSAMC, Universite Paul Sabatier; Andersen, Richard; Barros, Noemi; Maynau, Daniel et al.
Object Type: Article
System: The UNT Digital Library
The Engineering Design of the 1.5 m Diameter Solenoid for the MICERFCC Modules (open access)

The Engineering Design of the 1.5 m Diameter Solenoid for the MICERFCC Modules

The RF coupling coil (RFCC) module of MICE is where muonsthat have been cooled within the MICE absorber focus (AFC) modules arere-accelerated to their original longitudinal momentum. The RFCC moduleconsists of four 201.25 MHz RF cavities in a 1.4 meter diameter vacuumvessel. The muons are kept within the RF cavities by the magnetic fieldgenerated by a superconducting coupling solenoid that goes around the RFcavities. The coupling solenoid will be cooled using a pair of 4 K pulsetube cooler that will generate 1.5 W of cooling at 4.2 K. The magnet willbe powered using a 300 A two-quadrant power supply. This report describesthe ICST engineering design of the coupling solenoid forMICE.
Date: August 27, 2007
Creator: Wang, L.; Green, M. A.; Xu, F. Y.; Wu, H.; Li, L. K.; Gou, C. S. et al.
Object Type: Article
System: The UNT Digital Library
Characterization of Nuclear Fuel using Multivariate Statistical Analysis (open access)

Characterization of Nuclear Fuel using Multivariate Statistical Analysis

Various combinations of reactor type and fuel composition have been characterized using principle components analysis (PCA) of the concentrations of 9 U and Pu isotopes in the 10 fuel as a function of burnup. The use of PCA allows the reduction of the 9-dimensional data (isotopic concentrations) into a 3-dimensional approximation, giving a visual representation of the changes in nuclear fuel composition with burnup. Real-world variation in the concentrations of {sup 234}U and {sup 236}U in the fresh (unirradiated) fuel was accounted for. The effects of reprocessing were also simulated. The results suggest that, 15 even after reprocessing, Pu isotopes can be used to determine both the type of reactor and the initial fuel composition with good discrimination. Finally, partial least squares discriminant analysis (PSLDA) was investigated as a substitute for PCA. Our results suggest that PLSDA is a better tool for this application where separation between known classes is most important.
Date: November 27, 2007
Creator: Robel, M; Robel, M; Robel, M; Kristo, M J & Kristo, M J
Object Type: Article
System: The UNT Digital Library