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Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.

This was a four year grant commencing October 1, 2003 and finishing September 30, 2007. The funding was primarily used to support the work of the Principal Investigator, who collaborated with Profs. Scott Parker and John Cary at U. Colorado, and with two students, N. Xiang and J. Cheng also of U. Colorado. The technical accomplishments of this grant can be found in the publications listed in the final Section here. The main accomplishments of the grant work were: (1) Development and implementation of time-implicit two-fluid simulation methods in collaboration with the NIMROD team; and (2) Development and testing of a new time-implicit delta-f, energy-conserving method The basic two-fluid method, with many improvements is used in present NIMROD calculations. The energy-conserving delta-f method is under continuing development under contract between Coronado Consulting, a New Mexico sole proprietorship and the Oak Ridge National Laboratory.

Objective: This project seeks to improve the application of noble gas isotope studies to multiphase fluid processes in the Earth's crust by (1) identifying the important noble gas carrier phases in sediments to address the processes that have led to the observed enrichment and depletion patterns in sedimentary rocks and fluids, (2) examine the mechanisms by which such noble gas patterns are acquired, trapped and subsequently released to mobile crustal fluids, and (3) evaluate the time and length scales for the transport of noble gas components, such as radiogenic 4He, through the continental crust.. Project Description: Sedimentary rocks and oil field gases typically are enriched in heavy noble gases: Xe/Ar ratios of ~10-10,000 times the ratio in air have been observed that cannot be explained by adsorption hypotheses. Laboratory experiments designed to isolate sedimentary phases for noble gas analysis are conducted to identify the carrier phase(s). It has been observed that radiogenic 4He accumulates in confined aquifer waters at rates that exceed the rate of local production and approaching the whole crustal production rate. A literature evaluation of 4He, 3He crustal fluxes is being conducted to evaluate crustal scale mass transport in terms of the rate, mechanisms, temporal and spatial …

The ultimate goal of batch-melting studies, laboratory-scale, large-scale, or mathematical modeling is to increase the rate of glass processing in an energy-efficient manner. Mathematical models are not merely an intermediate step between laboratory-scale and large-scale studies, but are also an important tool for assessing the responses of melters to vast combinations of process parameters. In the simplest melting situation considered in this study, a cold cap of uniform thickness rests on a pool of molten glass from which it receives a steady uniform heat flux. Thus, as the feed-to-glass conversion proceeds, the temperature, velocity, and extent of feed reactions are functions of the position along the vertical coordinate, and these functions do not vary with time. This model is used for the sensitivity analyses on the effects of key parameters on the cold-cap behavior.

This is a feasibility study of using a modern Graphics Processing Unit (GPU) to parallelize the accelerator particle tracking code. To demonstrate the massive parallelization features provided by GPU computing, a simplified TracyGPU program is developed for dynamic aperture calculation. Performances, issues, and challenges from introducing GPU are also discussed. General purpose Computation on Graphics Processing Units (GPGPU) bring massive parallel computing capabilities to numerical calculation. However, the unique architecture of GPU requires a comprehensive understanding of the hardware and programming model to be able to well optimize existing applications. In the field of accelerator physics, the dynamic aperture calculation of a storage ring, which is often the most time consuming part of the accelerator modeling and simulation, can benefit from GPU due to its embarrassingly parallel feature, which fits well with the GPU programming model. In this paper, we use the Tesla C2050 GPU which consists of 14 multi-processois (MP) with 32 cores on each MP, therefore a total of 448 cores, to host thousands ot threads dynamically. Thread is a logical execution unit of the program on GPU. In the GPU programming model, threads are grouped into a collection of blocks Within each block, multiple threads share the …

To address the {sup 65}Zn contamination issue in the TEF, a multi-task experimental program was initiated. The first experimental task was completed and is reported in Ref. 1. The results of the second experimental task are reported here. This task examined the effect of filter temperature on trapping efficiency and deposit morphology. Based on the first experimental tasks that examined filter pore size and trapping efficiency, stainless steel filter media with a 20 {micro}m pore size was selected. A series of experiments using these filters was conducted during this second task to determine the effect of filter temperature on zinc vapor trapping efficiency, adhesion and morphology. The tests were conducted with the filters heated to 60, 120, and 200 C; the zinc source material was heated to 400 C for all the experiments to provide a consistent zinc source. The samples were evaluated for mass change, deposit adhesion and morphology. As expected from the physical vapor deposition literature, a difference in deposit morphology and appearance was observed between the three filter temperatures. The filter held at 60 C had the largest average mass gain while the 120 and 200 C filters exhibited similar but lower weight gains. The standard deviations …

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is a Nd:Glass laser facility capable of producing 1.8 MJ and 500 TW of ultraviolet light. This world's most energetic laser system is now operational with the goals of achieving thermonuclear burn in the laboratory and exploring the behavior of matter at extreme temperatures and energy densities. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in the interiors of planetary and stellar environments. On September 29, 2010, NIF performed the first integrated ignition experiment which demonstrated the successful coordination of the laser, the cryogenic target system, the array of diagnostics and the infrastructure required for ignition. Many more experiments have been completed since. In light of this strong progress, the U.S. and the international communities are examining the implication of achieving ignition on NIF for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a …

This report discusses the Family Planning Program, Title X of the Public Health Service Act, through which the federal government provides grants for voluntary family planning services.

This report discusses historical development and legal authorities related to contracting programs for Alaska Native Corporations.

Correspondence issued by the Government Accountability Office with an abstract that begins "Our work over the past several years has highlighted long-standing, widespread, and significant problems with improper payments in the federal government. Fiscal year 2010 marked the seventh year of implementation of the Improper Payments Information Act of 2002 (IPIA), which requires executive branch agencies to annually review all programs and activities to identify those that are susceptible to significant improper payments, estimate the annual amount of improper payment for such programs and activities, report these estimates, and report on actions taken to reduce any improper payment estimates that exceed $10 million. On July 22, 2010, the Improper Payments Elimination and Recovery Act of 2010 (IPERA) was enacted. IPERA amended IPIA by expanding on the previous requirements for identifying, estimating, and reporting on programs and activities susceptible to significant improper payments and to expand requirements for recovering overpayments across a broad range of federal programs. IPERA provisions related to identifying, estimating, and reporting on improper payments generally become effective in fiscal year 2011. For fiscal year 2010, federal agencies reported an estimated $125.4 billion in improper payments, an increase of about $16 billion over the fiscal year 2009 estimate …

Correspondence issued by the Government Accountability Office with an abstract that begins "In June 2009, following the expenditure of close to $3 billion and a critical Nunn-McCurdy breach of the cost growth threshold, the Department of Defense (DOD) terminated the Navy's VH-71 presidential helicopter acquisition program and contract because of cost growth, schedule delays, and projected system performance. The Presidential Helicopter VXX program is a successor Navy program to the terminated VH-71 program acquisition and has been initiated to develop aircraft to replace the current, aging presidential helicopter fleet. The Ike Skelton National Defense Authorization Act for Fiscal Year 2011 (the Act) directed GAO to review and report annually to the congressional defense committees on the VXX program through 2013. This is the first of the required GAO reports. It discusses (1) major lessons learned from the terminated VH-71 program that should be applied to the follow-on VXX program and (2) the current acquisition approach of the VXX program and sufficiency of the underlying acquisition plans and related documentation."

A letter report issued by the Government Accountability Office with an abstract that begins "Congress passed the Oil Pollution Act in 1990 (OPA). Among other things, OPA established the Interagency Coordinating Committee on Oil Pollution Research (interagency committee) to coordinate an oil pollution research program among federal agencies, including developing a plan, having the National Academy of Sciences review that plan, and reporting to Congress on the interagency committee's efforts biennially. The 2010 Deepwater Horizon explosion and fire led to the largest oil spill in U.S. history, raising new concerns about the effects of oil spills. GAO was asked to assess the extent to which the interagency committee has facilitated the coordination of federal agencies' oil pollution research. (The Chairman, Subcommittee on Energy and Environment, House Committee on Science and Technology, now retired; and Representative Woolsey initiated this request.) In part, GAO analyzed committee documents and biennial reports and interviewed agency officials and nonfederal research entities."

A letter report issued by the Government Accountability Office with an abstract that begins "Debt protection and credit insurance products can cancel or suspend part or all of a credit card debt under specific circumstances, such as loss of life, disability, or involuntary unemployment. In response to a mandate in the Credit Card Accountability Responsibility and Disclosure Act of 2009, this report reviews these products' market share and characteristics, federal and state oversight, and advantages and disadvantages to consumers. For this report, GAO analyzed data it had requested on these products from three major credit insurers and the nine largest credit card issuers. These nine issuers represented 85 percent of the credit card market. GAO also reviewed the products' terms and conditions, related marketing materials, and applicable federal and state regulations."

This report gives a summary of the usage of the War Powers Resolution (WPR) and various issues related to proposals to modify or repeal the resolution. The report summarizes most recent developments and background, and gives an overview of United Nations actions, and WPR activities in former Yugoslavia/Bosnia, Kosovo, Iraq (post-1991), Haiti, and Somalia. It also includes commentary on the instances formally reported under the WPR, consultation with Congress, and the current issues which Congress is considering.

This report provides an overview of nanotechnology, the National Nanotechnology Initiative, possible reauthorization of the 21st Century Nanotechnology Research and Development Act of 2003 (P.L. 108-153), and appropriations issues.

This report presents current data on estimated ownership of U.S. Treasury securities and major holders of federal debt by country. Federal debt represents the accumulated balance of borrowing by the federal government.

This report describes the characteristics of fossil fuels that make it necessary to use precise terminology, summarizes the major terms and their meanings, and provides a brief summary of the United States’ endowment of fossil fuels and the relationship between the U.S. fossil fuel energy endowment and those of other nations.

This report covers the background, recent politics, governant, and economy of Senegal. It also looks at security and human rights issues and Senegal's ties with France and the Middle East. It ends with a look at U.S. - Senegal relations.

The Department of Veterans Affairs (VA) administers a Travel Beneficiary Program to help alleviate the costs of travel to medical appointments for eligible veterans. This report offers an overview of the benefit and includes a question-and-answer section with basic information about eligibility, the types of travel covered and how benefits are calculated, and how to apply for the benefit. The report also includes an appendix containing a review of major legislative and regulatory changes to the benefit since its inception in 1940 through the most recent changes enacted in 2010.

This report presents data regarding the persons killed, missing, and buildings totally or partially damaged after the disaster in Japan. The report discusses the economic impact the disaster had on Japan and the impact on U.S. imports from and exports to Japan.

This report evaluates design elements of previous Clean Energy Standards (CES) proposals, summarizes the Administration’s CES policy framework, provides state-level baseline CES compliance analysis, and presents several policy options that Congress might consider as part of a CES debate.

This report looks at the activities and effectiveness of non-governmental organizations (NGOs) - non-profit, charitable institutions - in the lives of ordinary North Koreans. The role of NGOs in North Korea may re-emerge as a congressional interest, as the Obama Administration has expressed interest in restarting humanitarian assistance to North Korea.

This report summarizes the FY2011 budget request for research & development (R&D) funding, including comparisons to R&D funding requests in the FY2010 budget. Congress will play a central role in defining the nation's R&D priorities, especially with respect to two overarching issues: the extent to which the Federal R&D investment can grow in the context of increased pressure on discretionary spending and how available funding will be prioritized and allocated. This report breaks down in detail the various aspects of the President's FY2011 R&D funding request.