States

30 years of high-intensity negative ion sources for accelerators (open access)

30 years of high-intensity negative ion sources for accelerators

Thirty years ago, July 1, 1971, significant enhancement of negative ion emission from a gas discharge following an admixture of cesium was observed for the first time. This observation became the basis for the development of Surface Plasma Sources (SPS) for efficient production of negative ions from the interaction of plasma particles with electrodes on which adsorbed cesium reduced the surface work-function. The emission current density of negative ions increased rapidly from j {approximately} 10 mA/cm{sup 2} to 3.7 A/cm{sup 2} with a flat cathode and up to 8 A/cm{sup 2} with an optimized geometrical focusing in the long pulse SPS, and to 0.3 A/cm{sup 2} for DC SPS, recently increased up to 0.7 A/cm{sup 2}. Discovery of charge-exchange cooling helped decrease the negative ion temperature T below 1 eV, and increase brightness by many orders to a level compatible with the best proton sources, B = j/T> 1 A/cm{sup 2} eV. The combination of the SPS with charge-exchange injection improved large accelerators operation and has permitted beam accumulation up to space-charge limit and overcome this limit several times. The early SPS for accelerators have been in operation without modification for {approximately} 25 years. Advanced version of the SPS for …
Date: July 25, 2001
Creator: Dudnikov, Vadim
Object Type: Article
System: The UNT Digital Library
Achieving closure at Fernald (open access)

Achieving closure at Fernald

When Fluor Fernald took over the management of the Fernald Environmental Management Project in 1992, the estimated closure date of the site was more than 25 years into the future. Fluor Fernald, in conjunction with DOE-Fernald, introduced the Accelerated Cleanup Plan, which was designed to substantially shorten that schedule and save taxpayers more than $3 billion. The management of Fluor Fernald believes there are three fundamental concerns that must be addressed by any contractor hoping to achieve closure of a site within the DOE complex. They are relationship management, resource management and contract management. Relationship management refers to the interaction between the site and local residents, regulators, union leadership, the workforce at large, the media, and any other interested stakeholder groups. Resource management is of course related to the effective administration of the site knowledge base and the skills of the workforce, the attraction and retention of qualified a nd competent technical personnel, and the best recognition and use of appropriate new technologies. Perhaps most importantly, resource management must also include a plan for survival in a flat-funding environment. Lastly, creative and disciplined contract management will be essential to effecting the closure of any DOE site. Fluor Fernald, together with …
Date: February 25, 2001
Creator: Bradburne, John & Patton, Tisha C.
Object Type: Article
System: The UNT Digital Library
ADVANCED DIAGNOSTIC TECHNIQUES FOR THREE-PHASE SLURRY BUBBLE COLUMN REACTORS (SBCR) (open access)

ADVANCED DIAGNOSTIC TECHNIQUES FOR THREE-PHASE SLURRY BUBBLE COLUMN REACTORS (SBCR)

This report summarizes the accomplishment made during the second year of this cooperative research effort between Washington University, Ohio State University and Air Products and Chemicals. The technical difficulties that were encountered in implementing Computer Automated Radioactive Particle Tracking (CARPT) in high pressure SBCR have been successfully resolved. New strategies for data acquisition and calibration procedure have been implemented. These have been performed as a part of other projects supported by Industrial Consortium and DOE via contract DE-2295PC95051 which are executed in parallel with this grant. CARPT and Computed Tomography (CT) experiments have been performed using air-water-glass beads in 6 inch high pressure stainless steel slurry bubble column reactor at selected conditions. Data processing of this work is in progress. The overall gas holdup and the hydrodynamic parameters are measured by Laser Doppler Anemometry (LDA) in 2 inch slurry bubble column using Norpar 15 that mimic at room temperature the Fischer Tropsch wax at FT reaction conditions of high pressure and temperature. To improve the design and scale-up of bubble column, new correlations have been developed to predict the radial gas holdup and the time averaged axial liquid recirculation velocity profiles in bubble columns.
Date: July 25, 2001
Creator: Al-Dahhan, M.H.; Dudukovic, M.P. & Fan, L.S.
Object Type: Report
System: The UNT Digital Library
Advanced Method of Inspecting Tubular Goods and Refinery Process Piping: Inventions and Innovation Petroleum Project Fact Sheet (open access)

Advanced Method of Inspecting Tubular Goods and Refinery Process Piping: Inventions and Innovation Petroleum Project Fact Sheet

Project fact sheet written for the Inventions and Innovation Program about an advanced analysis method that provides complete on-line ultrasonic inspection of tubular materials.
Date: January 25, 2001
Creator: Wogsland, J.
Object Type: Book
System: The UNT Digital Library
Agricultural Trade Issues in the 107th Congress (open access)

Agricultural Trade Issues in the 107th Congress

The 107th Congress will consider and seek to influence trade issues with implications for the U.S. agricultural sector. Trade in agricultural commodities and food products affects farm income and rural employment, and it also generates economic activity beyond the farm gate. With agricultural export sales accounting for one-quarter of farm income, policymakers view U.S. efforts to develop market opportunities overseas as vital to the sector's financial health. Decisions taken by the Bush Administration, and actions taken by Congress, thus will affect the outlook for agricultural trade.
Date: May 25, 2001
Creator: Hanrahan, Charles E.; Jurenas, Remy & Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Air Pollution: Air Quality and Respiratory Problems in and Near the Great Smoky Mountains (open access)

Air Pollution: Air Quality and Respiratory Problems in and Near the Great Smoky Mountains

A briefing report issued by the General Accounting Office with an abstract that begins "Concerns have been growing about the air quality, visibility, and respiratory illnesses around the Great Smoky Mountains National Park, which straddles the border between North Carolina and Tennessee. This report analyzes recent trends in and contributing factors to (1) visibility impairments, (2) ground-level ozone, and (3) respiratory illnesses. This report also examines the Tennessee Valley Authority's (TVA) plans to reduce its emission of regulated pollutants from generating electricity. Visibility impairments and ozone are largely attributable to the following three types of emissions: sulfur dioxide, nitrogen oxides, and volatile organic compounds. The counties that border the park generally have slightly higher mortality rates from two types of respiratory illness. The three types of emissions interact in the atmosphere to form ozone gas and sulfate particles, which are linked to respiratory illnesses. In response to federal laws and other factors, TVA is making substantial environment-related investments and expects to reduce its annual emissions of sulfur dioxide by 40 percent and its "ozone-season"' emissions of nitrogen oxides by 70 percent between 1999 and 2005."
Date: May 25, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Air Pollution: Air Quality and Respiratory Problems in and Near the Great Smoky Mountains (open access)

Air Pollution: Air Quality and Respiratory Problems in and Near the Great Smoky Mountains

Testimony issued by the General Accounting Office with an abstract that begins "Concerns have been growing about the air quality, visibility, and respiratory illnesses around the Great Smoky Mountains National Park, which straddles the border between North Carolina and Tennessee. This testimony analyzes recent trends in and contributing factors to (1) visibility impairments, (2) ground-level ozone, and (3) respiratory illnesses. This testimony also examines the Tennessee Valley Authority's (TVA) plans to reduce its emission of regulated pollutants. Visibility impairments and ozone are largely attributable to the following three types of emissions: sulfur dioxide, nitrogen oxides, and volatile organic compounds. The counties that border the park generally have slightly higher mortality rates from two types of respiratory illness. The three types of emissions interact in the atmosphere to form ozone gas and sulfate particles, which are linked to respiratory illnesses. In response to federal laws and other factors, TVA is making substantial environment-related investments and expects to reduce its annual emissions of sulfur dioxide by 36 percent and its "ozone-season" emissions of nitrogen oxides by 68 percent between 1999 and 2005. This testimony summarizes a May report, (GAO-01-658)."
Date: May 25, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
The Alabama School Prayer Case: Chandler v. Siegelman (open access)

The Alabama School Prayer Case: Chandler v. Siegelman

This report considers the events of Chandler v. James in 1997. The case was a federal district court ruling in Alabama holding up a statute to violate the establishment of religion of the First amendment. The Governor attempted to appeal the court's position to both the Supreme Court and the circuit court but was denied.
Date: June 25, 2001
Creator: Ackerman, David M.
Object Type: Report
System: The UNT Digital Library
Amtrak: Overview and Options (open access)

Amtrak: Overview and Options

This report discusses Amtrak, an intercity railway transit system that being operatios in 1971. Amtrak receives considerable criticism for its inability to make a profit. The central policy issue, which this report addresses, is the following: Given that a national system of passenger rail service appears to be inherently unprofitable, as is the case for other public services, do we as a Nation wish to preserve our system or to liquidate it?
Date: January 25, 2001
Creator: Peterman, David Randall
Object Type: Report
System: The UNT Digital Library
Anti-Drug Media Campaign: Aspects of Advertising Contract Mismanaged by the Government; Contractor Improperly Charged Some Costs (open access)

Anti-Drug Media Campaign: Aspects of Advertising Contract Mismanaged by the Government; Contractor Improperly Charged Some Costs

A letter report issued by the General Accounting Office with an abstract that begins "This report discusses the Office of National Drug Control Policy's (ONDCP) advertising contract for Phase III of the National Youth Anti-Drug Media Campaign. The contractor for the advertising portion of the Phase III anti-drug media campaign did not properly charge the government for some of the labor costs incurred under the contract. Ogilvy & Mather's submission of time sheets claiming hours that some employees said they did not work on the anti-drug media campaign was clearly improper. Moreover, Ogilvy should not have been awarded a cost accounting standards (CAS)-covered cost-reimbursement government contract until the company had an adequate cost accounting system to support this type of contract. The government poorly managed aspects of the award and administration of the contract. The Department of Health and Human Services (HHS) should not have awarded this cost-reimbursement contract without determining whether the contractor had an adequate cost accounting system that met CAS standards. In addition, HHS should have reviewed the appropriateness of the large amount of money that the contracting officer's technical representative (COTR) recommended be disallowed from the contractor's invoices or arranged for an audit of the contract. …
Date: June 25, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Association of N2-fixing cyanobacteria and plants: towards novel symbioses of agricultural importance (open access)

Association of N2-fixing cyanobacteria and plants: towards novel symbioses of agricultural importance

Some nitrogen-fixing cyanobacteria are able to form symbioses with a wide variety of plants. Nostoc 2S9B is unusual in its ability to infect the roots of wheat, raising the prospect of a productive association with an important crop plant. The goal of the project was to lay the groundwork for the use of novel associations between Nostoc and crops of agronomic importance, thereby reducing our reliance on nitrogenous fertilizer. Nostoc 2S9B was found to enter roots through mechanical damage of roots and reside primarily in intercellular spaces. The strain could also be incorporated into wheat calli grown in tissue culture. In both cases, the rate of nitrogen fixation by the cyanobacterium was higher than that of the same strain grown with no plant present. Artificial nodules induced by the action of hormone 2,4D were readily infected by Nostoc 2S9B, and the cyanobacteria within such nodules fixed nitrogen under fully aerobic conditions. The nitrogen fixed was shown to be incorporated into the growing wheat seedlings. Nostoc thus differs from other bacteria in its ability to fix nitrogen in para-nodules without need for artificially microaerobic conditions. It would be useful to introduce foreign DNA into Nostoc 2S9B in order to make defined …
Date: June 25, 2001
Creator: Elhai, Jeff
Object Type: Report
System: The UNT Digital Library
Atomistic Simulation of Vacancy and Self-Interstitial Diffusion in Fe-Cu Alloys (open access)

Atomistic Simulation of Vacancy and Self-Interstitial Diffusion in Fe-Cu Alloys

Neutron hardening and embrittlement of pressure vessel steels is due to a high density of nanometer scale features, including Cu-rich precipitates which form as a result of radiation enhanced diffusion. High-energy displacement cascades generate large numbers of both isolated point defects and clusters of vacancies and interstitials. The subsequent clustering, diffusion and ultimate annihilation of primary damage is inherently coupled with solute transport and hence, the overall chemical and microstructural evolutions under irradiation. In this work, we present atomistic simulation results, based on many-body interatomic potentials, of the migration of vacancies, solute and self-interstitial atoms (SIA) in pure Fe and binary Fe-0.9 and 1.0 at.% Cu alloys. Cu diffusion occurs by a vacancy mechanism and the calculated Cu diffusivity is in good agreement with experimental data. Strain field interactions between the oversized substitutional Cu solute atoms and SIA and SIA clusters are predominantly repulsive and result in both a decreased activation energy and diffusion pre-factor for SIA and small (N < 5) SIA cluster migration, which occurs by three-dimensional motion. The Cu appears to enhance the reorientation of the SIA clusters to different <111> directions, as well as the transition from <110> to mobile <111> configurations. The migration behavior of …
Date: January 25, 2001
Creator: Marian, J.; Wirth, B. D.; Perlado, J. M.; Odette, G. R. & Diaz de la Rubia, T.
Object Type: Article
System: The UNT Digital Library
AUTOMATED RADIOLOGICAL MONITORING AT A RUSSIAN MINISTRY OF DEFENCE NAVAL SITE. (open access)

AUTOMATED RADIOLOGICAL MONITORING AT A RUSSIAN MINISTRY OF DEFENCE NAVAL SITE.

The Arctic Military Environmental Cooperation (AMEC) Program is a cooperative effort between the military establishments of the Kingdom of Norway, the Russian Federation, and the US. This paper discusses joint activities conducted over the past year among Norwegian, Russian, and US technical experts on a project to develop, demonstrate and implement automated radiological monitoring at Russian Navy facilities engaged in the dismantlement of nuclear-powered strategic ballistic missile launching submarines. Radiological monitoring is needed at these facilities to help protect workers engaged in the dismantlement program and the public living within the footprint of routine and accidental radiation exposure areas. By providing remote stand-alone monitoring, the Russian Navy will achieve added protection due to the defense-in-depth strategy afforded by local (at the site), regional (Kola) and national-level (Moscow) oversight. The system being implemented at the Polyaminsky Russian Naval Shipyard was developed from a working model tested at the Russian Institute for Nuclear Safety, Moscow, Russia. It includes Russian manufactured terrestrial and underwater gamma detectors, smart controllers for graded sampling, radio-modems for offsite transmission of the data, and a data fusion/display system: The data fusion/display system is derived from the Norwegian Picasso AMEC Environmental Monitoring software package. This computer package allows monitoring …
Date: February 25, 2001
Creator: Moskowitz, P. D.; Pomerville, J.; Gavrilov, S.; Kisselev, V.; Daniylan, V.; Belikov, A. et al.
Object Type: Article
System: The UNT Digital Library
AUTOMATED RADIOLOGICAL MONITORING AT A RUSSIAN MINISTRY OF DEFENSE NAVAL SITE. (open access)

AUTOMATED RADIOLOGICAL MONITORING AT A RUSSIAN MINISTRY OF DEFENSE NAVAL SITE.

The Arctic Military Environmental Cooperation (AMEC) Program is a cooperative effort between the military establishments of the Kingdom of Norway, the Russian Federation, and the US. This paper discusses joint activities conducted over the past year among Norwegian, Russian, and US technical experts on a project to develop, demonstrate and implement automated radiological monitoring at Russian Navy facilities engaged in the dismantlement of nuclear-powered strategic ballistic missile launching submarines. Radiological monitoring is needed at these facilities to help protect workers engaged in the dismantlement program and the public living within the footprint of routine and accidental radiation exposure areas. By providing remote stand-alone monitoring, the Russian Navy will achieve added protection due to the defense-in-depth strategy afforded by local (at the site), regional (Kola) and national-level (Moscow) oversight. The system being implemented at the Polyaminsky Russian Naval Shipyard was developed from a working model tested at the Russian Institute for Nuclear Safety, Moscow, Russia. It includes Russian manufactured terrestrial and underwater gamma detectors, smart controllers for graded sampling, radio-modems for offsite transmission of the data, and a data fusion/display system: The data fusion/display system is derived from the Norwegian Picasso AMEC Environmental Monitoring software package. This computer package allows monitoring …
Date: February 25, 2001
Creator: Moskowitz, P. D.; Pomerville, J.; Gavrilov, S.; Kisselev, V.; Daniylan, V.; Belikov, A. et al.
Object Type: Article
System: The UNT Digital Library
Aviation Security: Vulnerabilities in, and Alternatives for, Preboard Screening Security Operations (open access)

Aviation Security: Vulnerabilities in, and Alternatives for, Preboard Screening Security Operations

Testimony issued by the General Accounting Office with an abstract that begins "A safe and secure civil aviation system is critical to the nation's overall security, physical infrastructure, and economy. Billions of dollars and countless programs and policies have gone into developing such a system. Although many of the specific factors contributing to the terrible events of September 11 are still unclear, it is apparent that our aviation security system is plagued by serious weaknesses that can have devastating consequences. Last year, as part of an undercover investigation, GAO special agents used fake law enforcement badges and credentials to gain access to secure areas at two airports. They were also issued tickets and boarding passes, and could have carried weapons, explosives, or other dangerous items onto the aircraft. GAO tests of airport screeners also found major shortcomings in their ability to detect dangerous items hidden on passengers or in carry-on luggage. These weaknesses have raised questions about the need for alternative approaches. In assessing alternatives, five outcomes should be considered: improving screener performance, establishing accountability, ensuring cooperation among stakeholders, moving people efficiently, and minimizing legal and liability issues."
Date: September 25, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Ca cofactor of the water-oxidation complex: Evidence for a Mn/Ca heteronuclear cluster (open access)

Ca cofactor of the water-oxidation complex: Evidence for a Mn/Ca heteronuclear cluster

Calcium and chloride are necessary cofactors for the proper function of the oxygen-evolving complex (OEC) of Photosystem II (PS II). Located in the thylakoid membranes of green plants, cyanobacteria and algae, PS II and the OEC catalyze the light-driven oxidation of water into dioxygen (released into the biosphere), protons and electrons for carbon fixation. The actual chemistry of water oxidation is performed by a cluster of four manganese atoms, along with the requisite cofactors Ca{sup 2+} and Cl{sup -}. While the Mn complex has been extensively studied by X-ray absorption techniques, comparatively less is known about the Ca{sup 2+} cofactor. The fewer number of studies on the Ca{sup 2+} cofactor have sometimes relied on substituting the native cofactor with strontium or other metals, and have stirred some debate about the structure of the binding site. past efforts using Mn EXAFS on Sr-substituted PSII are suggestive of a close link between the Mn cluster and Sr, within 3.5 {angstrom}. The most recent published study using Sr EXAFS on similar samples confirms this finding of a 3.5 {angstrom} distance between Mn and Sr. This finding was base3d on a second Fourier peak (R {approx} 3 {angstrom}) in the Sr EXAFS from functional …
Date: July 25, 2001
Creator: Cinco, Roehl M.; Robblee, John H.; Messinger, Johannes; Fernandez, Carmen; McFarlane, Karen L.; Pizarro, Shelly A. et al.
Object Type: Article
System: The UNT Digital Library
Cathodic Reduction of Passive Films on Iron in Borate and Phosphate Buffer Ph 8.4: Different Mechanisms Revealed by in Situ Techniques. (open access)

Cathodic Reduction of Passive Films on Iron in Borate and Phosphate Buffer Ph 8.4: Different Mechanisms Revealed by in Situ Techniques.

The electrochemical behavior of passive Fe and thin, sputter-deposited films of Fe{sub 2}O{sub 3} was studied in borate and phosphate buffer pH 8.4 solutions. Cyclic voltammograms and in situ light absorption measurements--which enable the monitoring of the oxide film thickness--indicate a similar behavior of the Fe electrode in both pH 8.4 solution, especially a presence of a oxide-free surface at low cathodic potentials. However, X-ray absorption near edge structure (XANES) studies--which allow a simultaneous monitoring of changes in the samples' average valency and thickness--reveal that the reactions taking place during reduction of the passive film on iron are completely different for the two electrolytes. In borate buffer (pH 8.4), reduction leads to a complete dissolution of the passive film and the end product of reduction is soluble Fe(2+). In phosphate buffer (pH 8.4), there is no dissolution in a direct step to low cathodic potentials, but the resulting reduction product is metallic iron. Hence, the formation of the bare oxide-free metal surface at cathodic potentials takes place by different mechanisms in the two pH 8.4 solutions, depending on the type of anion present in the solution.
Date: March 25, 2001
Creator: Schmuki, P.; Virtanen, S. & Isaacs, H. S.
Object Type: Article
System: The UNT Digital Library
Cathodic Reduction of Passive Films on Iron in Borate and Phosphate Buffer Ph 8.4: Different Mechanisms Revealed by in Situ Techniques. (open access)

Cathodic Reduction of Passive Films on Iron in Borate and Phosphate Buffer Ph 8.4: Different Mechanisms Revealed by in Situ Techniques.

The electrochemical behavior of passive Fe and thin, sputter-deposited films of Fe{sub 2}O{sub 3} was studied in borate and phosphate buffer pH 8.4 solutions. Cyclic voltammograms and in situ light absorption measurements--which enable the monitoring of the oxide film thickness--indicate a similar behavior of the Fe electrode in both pH 8.4 solution, especially a presence of a oxide-free surface at low cathodic potentials. However, X-ray absorption near edge structure (XANES) studies--which allow a simultaneous monitoring of changes in the samples' average valency and thickness - reveal that the reactions taking place during reduction of the passive film on iron are completely different for the two electrolytes. In borate buffer (pH 8.4), reduction leads to a complete dissolution of the passive film and the end product of reduction is soluble Fe(2+). In phosphate buffer (pH 8.4), there is no dissolution in a direct step to low cathodic potentials, but the resulting reduction product is metallic iron. Hence, the formation of the bare oxide-free metal surface at cathodic potentials takes place by different mechanisms in the two pH 8.4 solutions, depending on the type of anion present in the solution.
Date: March 25, 2001
Creator: Schmuki, P.; Virtanen, S. & Isaacs, H. S.
Object Type: Article
System: The UNT Digital Library
Characterization of Salt Particle Induced Corrosion Processes by Synchrotron Generated X-Ray Fluorescence and Complementary Surface Analysis Tools. (open access)

Characterization of Salt Particle Induced Corrosion Processes by Synchrotron Generated X-Ray Fluorescence and Complementary Surface Analysis Tools.

The benefits of using synchrotron-generated X-rays and X-ray fluorescence analysis in combination with other surface analysis techniques have been demonstrated. In studies of salt-induced corrosion, for example, the detection of Rb ions in the area of secondary spreading when salt-containing micro-droplets are placed on zinc surfaces, further supports a mechanism involving cation transport during the corrosion and spreading of corrosive salt on exposed metal surfaces. Specifically, the new analytical data shows that: (a) cations are transported radially from a primary drop formed from a salt deposit in a thin film of secondary spreading around the drop; (b) subsequently, micro-pools are formed in the area of secondary spreading, and it is likely that cations transported within the thin film accumulate in these micro-pools until the area is dehydrated; (c) the mechanism of cation transport into the area of secondary spreading does not include transport of the anions; and (d) hydroxide is the counter ion formed from oxygen reduction at the metal surface within the spreading layer. Data relevant to iron corrosion is also presented and the distinct differences relative to the zinc situation are discussed.
Date: March 25, 2001
Creator: Neufeld, A. K.; Cole, I. S.; Bond, A. M.; Isaacs, H. S. & Furman, S. A.
Object Type: Article
System: The UNT Digital Library
Children's Health Insurance: SCHIP Enrollment and Expenditure Information (open access)

Children's Health Insurance: SCHIP Enrollment and Expenditure Information

Correspondence issued by the General Accounting Office with an abstract that begins "Congress created the State Children's Health Insurance Program (SCHIP) in 1997 to reduce the number of uninsured poor children whose families incomes are too high to qualify for Medicaid. Congress appropriated $40 billion over 10 years (fiscal years 1998 through 2007) for SCHIP. Each state's SCHIP allotment is available as a federal match based on state expenditures. Although the SCHIP statute generally targets children in families with incomes up to 200 percent of the federal poverty level, 13 states' programs cover children in families above 200 percent of the federal poverty level. This report provides information on (1) enrollment and federal expenditures for SCHIP and estimates of the number of and costs to enroll eligible unenrolled children and income-eligible pregnant women and (2) factors that may influence states' future expenditures for SCHIP and the availability of funding for any program expansion."
Date: July 25, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
The Coastal Nonpoint Pollution Program: Status and Legislative Issues (open access)

The Coastal Nonpoint Pollution Program: Status and Legislative Issues

This report covers the status and legislative issues of the coastal non-point program.
Date: January 25, 2001
Creator: Copeland, Claudia
Object Type: Report
System: The UNT Digital Library
Compact neutron source development at LBNL (open access)

Compact neutron source development at LBNL

A compact neutron generator based on D-D or D-T fusion reactions is being developed at the Lawrence Berkeley National Laboratory. The deuterium or tritium ions are produced in a radio-frequency (RF) driven multicusp plasma source. Seven beamlets are extracted and are accelerated to energy of 100 keV by means of a three-electrode electrostatic accelerator column. The ion beam then impinges on a titanium coated copper target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated by fusion reaction. The development of the neutron tube is divided into three phases. First, the accelerator column is operated at hydrogen beam intensity of 15 mA. Second phase consists of deuterium beam runs at pulsed, low duty cycle 150 mA operation. The third phase consists of deuterium or tritium operation at 1.5 A beam current. Phase one is completed and the results of hydrogen beam testing are discussed. Low duty cycle 150 mA deuterium operation is being investigated. Neutron flux will be measured. Finally the phase three operation and the advance neutron generator designs are described.
Date: July 25, 2001
Creator: Reijonen, Jani; Lou, Tak Pui; Tolmachoff, Bryan & Leung, K. N.
Object Type: Article
System: The UNT Digital Library
Comparison of Linac Simulation Codes (open access)

Comparison of Linac Simulation Codes

The Spallation Neutron Source (SNS) project is a collaborative effort between Brookhaven, Argonne, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge National Laboratories. Los Alamos is responsible for the design of the linac for this accelerator complex. The code PARMILA, developed at Los Alamos is widely used for proton linac design and beam dynamics studies. The most updated version includes superconducting structures among others. In recent years, some other codes have also been developed which primarily focuses on the studies of the beam dynamics. In this paper, we compare the simulation results and discuss physics aspects of the different linac design and beam dynamics simulation codes.
Date: January 25, 2001
Creator: Nath, S.; Ryne, Robert D.; Stovall, J.; Takeda, H.; Xiang, J.; Young, L. et al.
Object Type: Article
System: The UNT Digital Library
Comparison of Refractory Performance in Black Liquor Gasifiers and a Smelt Test System (open access)

Comparison of Refractory Performance in Black Liquor Gasifiers and a Smelt Test System

Prior laboratory corrosion studies along with experience at the black liquor gasifier in New Bern, North Carolina, clearly demonstrate that serious material problems exist with the gasifier's refractory lining. Mullite-based and alumina-based refractories used at the New Bern facility suffered significant degradation even though they reportedly performed adequately in smaller scale systems. Oak Ridge National Laboratory's involvement in the failure analysis, and the initial exploration of suitable replacement materials, led to the realization that a simple and reliable, complementary method for refractory screening was needed. The development of a laboratory test system and its suitability for simulating the environment of black liquor gasifiers was undertaken. Identification and characterization of corrosion products were used to evaluate the test system as a rapid screening tool for refractory performance and as a predictor of refractory lifetime. Results from the test systems and pl ants were qualitatively similar.
Date: September 25, 2001
Creator: Peascoe, RA
Object Type: Article
System: The UNT Digital Library