Space Research: Content and Coordination of Space Science and Technology Strategy Need to Be More Robust (open access)

Space Research: Content and Coordination of Space Science and Technology Strategy Need to Be More Robust

A letter report issued by the Government Accountability Office with an abstract that begins "Each year, the United States spends billions of dollars on space-based systems to support national security activities. The National Defense Authorization Act for Fiscal Year 2010 requires the Department of Defense (DOD) and the Director of National Intelligence (DNI) to develop and issue a space science and technology (S&T) strategy every 2 years addressing S&T goals and a process for achieving these goals, among other requirements. As GAO is required to assess the strategy, this report addresses (1) the extent to which the strategy meets the statutory requirements, (2) if other approaches could be used to enhance the usefulness of the strategy, and (3) the extent of coordination efforts used in developing the strategy. GAO reviewed the strategy for sufficiency with statutory requirements and met with DOD and DNI officials to discuss the analyses and coordination used to support the content of the strategy. GAO also compared the strategy to strategic planning best practices to see if there are ways it could be improved."
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Pakistan Assistance: Relatively Little of the $3 Billion in Requested Assistance Is Subject to State's Certification of Pakistan's Progress on Nonproliferation and Counterterrorism Issues (open access)

Pakistan Assistance: Relatively Little of the $3 Billion in Requested Assistance Is Subject to State's Certification of Pakistan's Progress on Nonproliferation and Counterterrorism Issues

Correspondence issued by the Government Accountability Office with an abstract that begins "Pakistan is central to U.S. efforts to disrupt, dismantle, and defeat al Qaeda and deny its resurgence in the Afghanistan-Pakistan region. The United States has sought to secure these interests through counterterrorism and counterinsurgency cooperation, as well as through a long-term partnership anchored, in part, by increased civilian and military assistance. Since fiscal year 2002, the U.S. government has provided the Pakistani government almost $21 billion in assistance and reimbursements toward these goals. However, al Qaeda and other terrorists and violent extremists continue to promote instability and use safe havens in Pakistan's western border region to plan and train for attacks against U.S. interests. At the same time, the United States continues to be concerned with the ongoing effect of A. Q. Khan's illicit transfer of nuclear technology to Iran, North Korea, and Libya. To address these and other concerns, in October 2009, Congress enacted the Enhanced Partnership with Pakistan Act of 2009, which, among other things, limits certain security-related assistance to Pakistan each fiscal year from 2011 through 2014. Before the United States can provide security-related assistance to Pakistan in each of those fiscal years, the Secretary …
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
VA and DOD Health Care: First Federal Health Care Center Established, but Implementation Concerns Need to Be Addressed (open access)

VA and DOD Health Care: First Federal Health Care Center Established, but Implementation Concerns Need to Be Addressed

A letter report issued by the Government Accountability Office with an abstract that begins "The National Defense Authorization Act (NDAA) for Fiscal Year 2010 authorized the Departments of Veterans Affairs (VA) and Defense (DOD) to establish a 5-year demonstration project to integrate VA and DOD medical care into a first-of-its- kind Federal Health Care Center (FHCC) in North Chicago, Illinois. Expectations for the FHCC are outlined in an Executive Agreement signed by VA and DOD in April 2010. The NDAA for Fiscal Year 2010 also directed GAO to annually evaluate various aspects of the FHCC integration. This report examines (1) what progress VA and DOD have made implementing the Executive Agreement to establish and operate the FHCC and (2) what plan, if any, VA and DOD have to assess FHCC provision of care and operations. GAO reviewed FHCC documents and conducted visits to the site; interviewed VA, DOD, and FHCC officials; and reviewed related GAO work."
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Bankruptcy: Complex Financial Institutions and International Coordination Pose Challenges (open access)

Bankruptcy: Complex Financial Institutions and International Coordination Pose Challenges

A letter report issued by the Government Accountability Office with an abstract that begins "The Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd- Frank Act) created the Orderly Liquidation Authority (OLA) that can be used to resolve failed systemically important financial institutions. However, questions continued to be raised about the effectiveness of the U.S. Bankruptcy Code (Code) and current mechanisms for international coordination in bankruptcy cases. The Dodd-Frank Act requires GAO to report on the effectiveness of the Code in resolving certain failed financial institutions on an ongoing basis. Among its objectives, this report addresses (1) the effectiveness of Chapters 7 and 11 of the Code for facilitating orderly resolutions of failed financial institutions; (2) proposals for improving the effectiveness of liquidations and reorganizations under the Code; and (3) existing mechanisms that facilitate international coordination under the Code and barriers to coordination of financial institution bankruptcies. GAO reviewed laws, judicial decisions, regulations, data, and academic literature on resolutions, and spoke with relevant government officials, industry representatives, and experts from the legal and academic communities about the effectiveness of the Code."
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Data Center Consolidation: Agencies Need to Complete Inventories and Plans to Achieve Expected Savings (open access)

Data Center Consolidation: Agencies Need to Complete Inventories and Plans to Achieve Expected Savings

A letter report issued by the Government Accountability Office with an abstract that begins "Over time, the federal government's demand for information technology has led to a dramatic rise in the number of federal data centers and an increase in operational costs. Recognizing this increase, the Office of Management and Budget (OMB) has launched a governmentwide initiative to consolidate data centers. GAO was asked to (1) assess whether agency consolidation documents include adequate detail for agencies to consolidate their centers, (2) identify the key consolidation challenges reported by agencies, and (3) evaluate whether lessons learned during state government consolidation efforts could be leveraged at the federal level. To address these objectives, GAO assessed the completeness of agency inventories and plans, interviewed agencies about their challenges, and evaluated the applicability of states' consolidation lessons to federal challenges."
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Mortgage Reform: Potential Impacts of Provisions in the Dodd-Frank Act on Homebuyers and the Mortgage Market (open access)

Mortgage Reform: Potential Impacts of Provisions in the Dodd-Frank Act on Homebuyers and the Mortgage Market

A publication issued by the Government Accountability Office with an abstract that begins "The Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd- Frank Act) is intended, among other things, to reform residential mortgage lending and securitization practices that contributed to the recent financial crisis. The act provides some liability protection for lenders originating mortgages that meet nine specified criteria, as applicable, associated with a borrower's ability to repay ("qualified mortgages"). The act also requires securitizers of mortgages not meeting separate criteria associated with lower default risk to retain at least 5 percent of the credit risk, though federal rulemaking agencies may vary this amount. The act directed GAO to assess the effect of mortgage-related provisions on the availability and affordability of mortgage credit and to issue a report by July 2011, but federal agencies are still developing implementing regulations. This report discusses the potential impact of the act's (1) qualified mortgage criteria, (2) credit risk retention requirement, and (3) provisions concerning homeownership counseling and regulation of high-cost loans."
Date: July 19, 2011
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Trade Adjustment Assistance (TAA) and Its Role in U.S. Trade Policy (open access)

Trade Adjustment Assistance (TAA) and Its Role in U.S. Trade Policy

This report looks at the background of Trade Adjustment Assistance (TAA) in the Trade Expansion Act of 1962, which was created by Congress. It then discusses how the 112th Congress is considering legislative action to extend the TAA - including two issues: how necessary or appropriate the extension is, and whether or not three proposed bills should be voted upon separately.
Date: July 19, 2011
Creator: Hornbeck, J. F. & Rover, Laine Elise
Object Type: Report
System: The UNT Digital Library
Soft ionization of thermally evaporated hypergolic ionic liquid aerosols (open access)

Soft ionization of thermally evaporated hypergolic ionic liquid aerosols

Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?]ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.
Date: July 19, 2011
Creator: Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg et al.
Object Type: Article
System: The UNT Digital Library
SYNTHESIS AND CHARACTERIZATION OF SMART FUNCTIONAL COATINGS BY CHEMICAL SOLUTION DEPOSITION METHODS (open access)

SYNTHESIS AND CHARACTERIZATION OF SMART FUNCTIONAL COATINGS BY CHEMICAL SOLUTION DEPOSITION METHODS

New coating technology enables the fabrication of low cost structural health monitoring (SHM) and tamper indication devices that can be employed to strengthen national and international safeguards objectives. In particular, such innovations could serve the safeguards community by improving both the timeliness of detection and confidence in verification and monitoring. This work investigates the synthesis of functional surface coatings using chemical solutions deposition methods. Chemical solution deposition has recently received attention in the materials research community due to its unique advantages such as low temperature processing, high homogeneity of final products and the ability to fabricate materials with controlled surface properties and pore structures. The synthesis of functional coatings aimed at modifying the materials conductivity and optical properties was investigated by the incorporation of transition element (e.g. Cr{sup +3}) and rare earth (e.g. Er{sup +3}) serving as dopants in a polymer or gel matrix. The structural and morphological investigation of the as-deposited films was carried out using UV/Vis and photoluminescence (PL) spectroscopy. The as deposited coating was further investigated by scanning electron microscopy and energy dispersive x-ray microscopy.
Date: July 19, 2011
Creator: Mendez-Torres, A.
Object Type: Article
System: The UNT Digital Library
Colliding Laser Pulses for Laser-Plasma Accelerator Injection Control (open access)

Colliding Laser Pulses for Laser-Plasma Accelerator Injection Control

Decoupling injection from acceleration is a key challenge to achieve compact, reliable, tunable laser-plasma accelerators (LPA). In colliding pulse injection the beat between multiple laser pulses can be used to control energy, energy spread, and emittance of the electron beam by injecting electrons in momentum and phase into the accelerating phase of the wake trailing the driver laser pulse. At LBNL, using automated control of spatiotemporal overlap of laser pulses, two-pulse experiments showed stable operation and reproducibility over hours of operation. Arrival time of the colliding beam was scanned, and the measured timing window and density of optimal operation agree with simulations. The accelerator length was mapped by scanning the collision point.
Date: July 19, 2011
Creator: Plateau, Guillaume; Geddes, Cameron; Matlis, Nicholas; Cormier-Michel, Estelle; Mittelberger, Daniel; Nakamura, Kei et al.
Object Type: Article
System: The UNT Digital Library
Self-Similar Nonlinear Dynamical Solutions for One-Component Nonneutral Plasma in a Time-Dependent Linear Focusing Field (open access)

Self-Similar Nonlinear Dynamical Solutions for One-Component Nonneutral Plasma in a Time-Dependent Linear Focusing Field

In a linear trap confining a one-component nonneutral plasma, the external focusing force is a linear function of the configuration coordinates and/or the velocity coordinates. Linear traps include the classical Paul trap and the Penning trap, as well as the newly proposed rotating-radio- frequency traps and the Mobius accelerator. This paper describes a class of self-similar nonlinear solutions of nonneutral plasma in general time-dependent linear focusing devices, with self-consistent electrostatic field. This class of nonlinear solutions includes many known solutions as special cases.
Date: July 19, 2011
Creator: Davidson, Hong Qin and Ronald C.
Object Type: Report
System: The UNT Digital Library
Suppressing Thermal Energy Drift In The LLNL Flash X-Ray Accelerator Using Linear Disk Resistor Stacks (open access)

Suppressing Thermal Energy Drift In The LLNL Flash X-Ray Accelerator Using Linear Disk Resistor Stacks

This paper addresses thermal drift in sodium thiosulfate liquid resistors and their replacement with linear disk resistors from HVR Advanced Power Components. Sodium thiosulfate resistors in the FXR induction linear accelerator application have a temperature coefficient of {approx}1.8%/C. The FXR Marx banks send an 8kJ pulse through eight 524 cm{sup 3} liquid resistors at a repetition rate of up to 1 every 45 seconds. Every pulse increases the temperature of the solution by {approx}0.4 C which produces a 0.7% change in resistance. The typical cooling rate is {approx}0.4 C per minute which results in {approx}0.1% energy drop per pulse during continuous pulsed operations. A radiographic accelerator is extraordinarily sensitive to energy variations. Changes in beam energy produce movement in beam transport, changes in spot size, and large dose variations. If self-heating were the only problem, we could predict the increase in input voltage required to compensate for the energy loss. However, there are other variables that influence the temperature of the resistors such as focus magnet heating, changes in room temperature, changes in cooling water, where the cell is located, etc. Additionally not all of the resistors have equivalent cooling rates and as many as 32 resistors are driven from …
Date: July 19, 2011
Creator: Kreitzer, B R; Houck, T L & Luchterhand, O C
Object Type: Article
System: The UNT Digital Library
Centroid and Envelope Eynamics of Charged Particle Beams in an Oscillating Wobbler and External Focusing Lattice for Heavy Ion Fusion Applications (open access)

Centroid and Envelope Eynamics of Charged Particle Beams in an Oscillating Wobbler and External Focusing Lattice for Heavy Ion Fusion Applications

Recent heavy ion fusion target studies show that it is possible to achieve ignition with direct drive and energy gain larger than 100 at 1MJ. To realize these advanced, high-gain schemes based on direct drive, it is necessary to develop a reliable beam smoothing technique to mitigate instabilities and facilitate uniform deposition on the target. The dynamics of the beam centroid can be explored as a possible beam smoothing technique to achieve a uniform illumination over a suitably chosen region of the target. The basic idea of this technique is to induce an oscillatory motion of the centroid for each transverse slice of the beam in such a way that the centroids of different slices strike different locations on the target. The centroid dynamics is controlled by a set of biased electrical plates called 'wobblers'. Using a model based on moments of the Vlasov-Maxwell equations, we show that the wobbler deflection force acts only on the centroid motion, and that the envelope dynamics are independent of the wobbler fields. If the conducting wall is far away from the beam, then the envelope dynamics and centroid dynamics are completely decoupled. This is a preferred situation for the beam wobbling technique, because …
Date: July 19, 2011
Creator: Logan, Ronald C. Davidson and B. Grant
Object Type: Report
System: The UNT Digital Library
X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator (open access)

X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) were measured using a photon-counting single-shot pixelated Silicon-based detector [3], providing for the first time direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray andelectron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion.
Date: July 19, 2011
Creator: Plateau, Guillaume; Geddes, Cameron; Thorn, Daniel; Matlis, Nicholas; Mittelberger, Daniel; Stoehlker, T et al.
Object Type: Article
System: The UNT Digital Library
Best Practices for Wind Energy Development in the Great Lakes Region (open access)

Best Practices for Wind Energy Development in the Great Lakes Region

This report offers a menu of 18 different, yet complementary, preferred practices and policies. The best practices cover all phases of the wind energy development process - from the policies that allow for wind development, to the sustainable operation of a wind project, to the best practices for decommissioning a spent turbine - including applications for offshore wind. Each best practice describes the opportunities and challenges (pros and cons), and offers a case example that illustrates how that best practice is being utilized by a particular jurisdiction or wind project. The practices described in this publication were selected by a diverse group of interests from the Great Lakes Wind Collaborative that included environmental groups, industry, academia, and federal, state and local government regulators. The practices were identified through a year-long process that included a literature review, online survey and interviews with individuals from the public, private and non-profit sectors. Optimally, a suite of these best practices would be applied in an appropriate combination to fit the conditions of a particular wind project or a set of wind projects within a given locality or region.
Date: July 19, 2011
Creator: Pebbles, Victoria; Hummer, John & Haven, Celia
Object Type: Text
System: The UNT Digital Library
Measuring Safeguards Culture (open access)

Measuring Safeguards Culture

As the International Atomic Energy Agency (IAEA) implements a State Level Approach to its safeguards verification responsibilities, a number of countries are beginning new nuclear power programs and building new nuclear fuel cycle faculties. The State Level approach is holistic and investigatory in nature, creating a need for transparent, non-discriminatory judgments about a state's nonproliferation posture. In support of this need, the authors previously explored the value of defining and measuring a state's safeguards culture. We argued that a clear definition of safeguards culture and an accompanying set of metrics could be applied to provide an objective evaluation and demonstration of a country's nonproliferation posture. As part of this research, we outlined four high-level metrics that could be used to evaluate a state's nuclear posture. We identified general data points. This paper elaborates on those metrics, further refining the data points to generate a measurable scale of safeguards cultures. We believe that this work could advance the IAEA's goals of implementing a safeguards system that is fully information driven, while strengthening confidence in its safeguards conclusions.
Date: July 19, 2011
Creator: Frazar, Sarah L. & Mladineo, Stephen V.
Object Type: Report
System: The UNT Digital Library
2011 Status of the Automatic Alignment System for the National Ignition Facility (open access)

2011 Status of the Automatic Alignment System for the National Ignition Facility

Automated alignment for the National Ignition Facility (NIF) is accomplished using a large-scale parallel control system that directs 192 laser beams along the 300-m optical path. The beams are then focused down to a 50-micron spot in the middle of the target chamber. The entire process is completed in less than 50 minutes. The alignment system commands 9,000 stepping motors for highly accurate adjustment of mirrors and other optics. 41 control loops per beamline perform parallel processing services running on a LINUX cluster to analyze high-resolution images of the beams and their references. This paper describes the status the NIF automatic alignment system and the challenges encountered as NIF development has transitioned from building the laser, to becoming a research project supporting a 24 hour, 7 day laser facility. NIF is now a continuously operated system where performance monitoring is increasingly more critical for operation, maintenance, and commissioning tasks. Equipment wear and the effects of high energy neutrons from fusion experiments are issues which alter alignment efficiency and accuracy. New sensors needing automatic alignment assistance are common. System modifications to improve efficiency and accuracy are prevalent. Handling these evolving alignment and maintenance needs while minimizing the impact on NIF experiment …
Date: July 19, 2011
Creator: Wilhelmsen, K.; Awwal, A.; Burkhart, S.; McGuigan, D.; Kamm, V. M.; Leach, R. et al.
Object Type: Article
System: The UNT Digital Library
National Ignition Campaign (NIC) Precision Tuning Series Shock Timing Experiments (open access)

National Ignition Campaign (NIC) Precision Tuning Series Shock Timing Experiments

A series of precision shock timing experiments have been performed on NIF. These experiments continue to adjust the laser pulse shape and employ the adjusted cone fraction (CF) in the picket (1st 2 ns of the laser pulse) as determined from the re-emit experiment series. The NIF ignition laser pulse is precisely shaped and consists of a series of four impulses, which drive a corresponding series of shock waves of increasing strength to accelerate and compress the capsule ablator and fuel layer. To optimize the implosion, they tune not only the strength (or power) but also, to sub-nanosecond accuracy, the timing of the shock waves. In a well-tuned implosion, the shock waves work together to compress and heat the fuel. For the shock timing experiments, a re-entrant cone is inserted through both the hohlraum wall and the capsule ablator allowing a direct optical view of the propagating shocks in the capsule interior using the VISAR (Velocity Interferometer System for Any Reflector) diagnostic from outside the hohlraum. To emulate the DT ice of an ignition capsule, the inside of the cone and the capsule are filled with liquid deuterium.
Date: July 19, 2011
Creator: Robey, H F & Celliers, P M
Object Type: Report
System: The UNT Digital Library
Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects (open access)

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.
Date: July 19, 2011
Creator: Pankin, Alexei Y. & Kritz, Arnold H.
Object Type: Report
System: The UNT Digital Library
PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS (open access)

PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS

Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within {+-}8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.
Date: July 19, 2011
Creator: Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; Tilborg, Jeroen van et al.
Object Type: Article
System: The UNT Digital Library
Best Practices for Sustainable WInd Energy Development in the Great Lakes Region and Beyond (open access)

Best Practices for Sustainable WInd Energy Development in the Great Lakes Region and Beyond

This document offers a menu of 18 different, yet complimentary preferred practices and policies. The best practices cover all phases of the wind energy development process - from the policies that allow for wind development, to the sustainable operation of a wind project, to the best practices for decommissioning a spent turbine - including applications for offshore wind. The practices include those that have been previously tested and proven effective, as well as new practices that were identified by experts in the field as needed for future wind developments. Each best practice includes information about the opportunities and challenges (pros and cons), and offers a case example that illustrates how that best practice is being utilized by a particular jurisdiction or wind project. The practices described in this publication were selected by a diverse group of interests from the Great Lakes Wind Collaborative that included environmental groups, industry, and federal, state and local government regulators. They were identified through a year long process that included a literature review, online survey and interviews with individuals from the public, private and non-profit sectors.
Date: July 19, 2011
Creator: Commission, Great Lakes; Pebbles, Victoria; Hummer, John & Haven, Celia
Object Type: Report
System: The UNT Digital Library
Experimental Verification of the Kruskal-Shafranov Stability Limit in Line-Tied Partial Toroidal Plasmas (open access)

Experimental Verification of the Kruskal-Shafranov Stability Limit in Line-Tied Partial Toroidal Plasmas

The stability properties of partial toroidal flux ropes are studied in detail in the laboratory, motivated by ubiquitous arched magnetic structures found on the solar surface. The flux ropes studied here are magnetized arc discharges formed between two electrodes in the Magnetic Reconnection Experiment (MRX) [Yamada et al., Phys. Plasmas, 4, 1936 (1997)]. The three dimensional evolution of these flux ropes is monitored by a fast visible light framing camera, while their magnetic structure is measured by a variety of internal magnetic probes. The flux ropes are consistently observed to undergo large-scale oscillations as a result of an external kink instability. Using detailed scans of the plasma current, the guide field strength, and the length of the flux rope, we show that the threshold for kink stability is governed by the Kruskal-Shafranov limit for a flux rope that is held fixed at both ends (i.e., qa = 1).
Date: July 19, 2011
Creator: Oz, E.; Myers, C. E.; Yamada, M.; Ji, H.; Kulsrud, R. M. & Xie, J.
Object Type: Report
System: The UNT Digital Library
Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks (open access)

Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ({var_epsilon}{sup -1}) larger than the E x B velocity, where {var_epsilon} is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.
Date: July 19, 2011
Creator: Qin, Hong; Guan, Xiaoyin & Fisch, Nathaniel J.
Object Type: Report
System: The UNT Digital Library
Cooling Water Intake Structures: Summary of EPA’s Proposed Rule (open access)

Cooling Water Intake Structures: Summary of EPA’s Proposed Rule

This report provides a summary of EPA’s Proposed Rule which is Cooling Water Intake Structures.water withdrawals by power producers and manufacturers represent more than one half of water withdrawn daily for various use in The United States.
Date: July 19, 2011
Creator: Claudia, Copleland
Object Type: Report
System: The UNT Digital Library