Comments on time-dependent lenses (TDLs) (open access)

Comments on time-dependent lenses (TDLs)

this is report is a written comment on the time-dependent lenses.
Date: August 27, 2004
Creator: Lee, Ed
Object Type: Report
System: The UNT Digital Library
Comparison of electron cloud simulation and experiments in the high-current experiment (open access)

Comparison of electron cloud simulation and experiments in the high-current experiment

A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.
Date: August 27, 2004
Creator: Cohen, R. H.; Friedman, A.; Covo, M. Kireeff; Lund, S. M.; Molvik, A. W.; Bieniosek, F. M. et al.
Object Type: Report
System: The UNT Digital Library
Comparisons of laboratory wavelength measurements with theoretical calculations for neon-like through lithium-like argon, sulfur, and silicon (open access)

Comparisons of laboratory wavelength measurements with theoretical calculations for neon-like through lithium-like argon, sulfur, and silicon

Atomic structure codes have a difficult time accurately calculating the wavelengths of many-electron ions without the benefit of laboratory measurements. This is especially true for wavelengths of lines in the extreme ultraviolet and soft x-ray regions. We are using the low-energy capability of the Livermore electron beam ion traps to compile a comprehensive catalog of astrophysically relevant emission lines in support of satellite x-ray observations. Our database includes wavelength measurements, relative intensities, and line assignments, and is compared to a full set of calculations using the Hebrew University - Lawrence Livermore Atomic Code (HULLAC). Mean deviation of HULLAC calculations from our measured wavelength values is highest for L-shell transitions of neon-like ions and lowest for lithium-like ions, ranging from a mean deviation of over 0.5 {angstrom} for Si V to 12 m{angstrom} in Ar XVI.
Date: August 27, 2004
Creator: Lepson, J K; Beiersdorfer, P; Behar, E & Kahn, S M
Object Type: Article
System: The UNT Digital Library
Computational Accelerator Physics Working Group Summary (open access)

Computational Accelerator Physics Working Group Summary

The working group on computational accelerator physics at the 11th Advanced Accelerator Concepts Workshop held a series of meetings during the Workshop. Verification, i.e., showing that a computational application correctly solves the assumed model, and validation, i.e., showing that the model correctly describes the modeled system, were discussed for a number of systems. In particular, the predictions of the massively parallel codes, OSIRIS and VORPAL, used for modeling advanced accelerator concepts, were compared and shown to agree, thereby establishing some verification of both codes. In addition, a number of talks on the status and frontiers of computational accelerator physics were presented, to include the modeling of ultrahigh-brightness electron photoinjectors and the physics of beam halo production. Finally, talks discussing computational needs were presented.
Date: August 27, 2004
Creator: Cary, John R. & Bohn, Courtlandt L.
Object Type: Article
System: The UNT Digital Library
Estimation of Tritium Annual Flux From Concrete Rubble Buried in the E-Area Slit Trenches (open access)

Estimation of Tritium Annual Flux From Concrete Rubble Buried in the E-Area Slit Trenches

A growing amount of concrete containing tritium is being generated as a result of ongoing demolition and destruction activities on the SRS. To assist in determining how much radioactive low level waste (such as the tritiated concrete) can be safely disposed, performance assessments are conducted. In the past, these calculations assumed that all the tritium associated with buried concrete existed on the exterior concrete surfaces. Although this is a conservative assumption with respect to the groundwater pathway, it is not accurate. The objective of this study was to more accurately model tritium release from concrete rubble. Particular attention was directed at incorporating tritium diffusion from the concrete rubble into the surrounding groundwater.
Date: August 27, 2004
Creator: KAPLAN, DANIEL
Object Type: Report
System: The UNT Digital Library

Internal Controls Over the Use of Oversight Funds

None
Date: August 27, 2004
Creator: White, H., Jr.
Object Type: Presentation
System: The UNT Digital Library
Novel Neutron Detector for High Rate Imaging Applications (open access)

Novel Neutron Detector for High Rate Imaging Applications

The Phase II period performance was May 30, 2002 through May 29, 2004. This development effort was successfully completed within the period and budget allotted. The proposed design was successfully fabricated from B{sub 4}C-coated aluminum and copper film, slit and wound to form 4 mm diameter straws, cut to 100 cm in length, and threaded with resistive anode wires (20 {micro}m in diameter). This paper reports testing done with two 50-straw detector modules at the reactor of the Nuclear Science Center at Texas A&M University (TAMU NSC).
Date: August 27, 2004
Creator: Lacy, Jeffrey, L.
Object Type: Report
System: The UNT Digital Library
Preclosure Seismic Design Methodology for a Geologic Repository at Yucca Mountain (open access)

Preclosure Seismic Design Methodology for a Geologic Repository at Yucca Mountain

None
Date: August 27, 2004
Creator: Coppersmith, K.
Object Type: Report
System: The UNT Digital Library
Propane Vehicle Demonstration Grant Program (open access)

Propane Vehicle Demonstration Grant Program

Project Description: Propane Vehicle Demonstration Grants The Propane Vehicle Demonstration Grants was established to demonstrate the benefits of new propane equipment. The US Department of Energy, the Propane Education & Research Council (PERC) and the Propane Vehicle Council (PVC) partnered in this program. The project impacted ten different states, 179 vehicles, and 15 new propane fueling facilities. Based on estimates provided, this project generated a minimum of 1,441,000 new gallons of propane sold for the vehicle market annually. Additionally, two new off-road engines were brought to the market. Projects originally funded under this project were the City of Portland, Colorado, Kansas City, Impco Technologies, Jasper Engines, Maricopa County, New Jersey State, Port of Houston, Salt Lake City Newspaper, Suburban Propane, Mutual Liquid Propane and Ted Johnson.
Date: August 27, 2004
Creator: Mallinger, Jack
Object Type: Report
System: The UNT Digital Library
Science and Technology Review October 2004 (open access)

Science and Technology Review October 2004

None
Date: August 27, 2004
Creator: Henson, V. E.
Object Type: Report
System: The UNT Digital Library
Time-dependence ion charge state distributions of vacuum arcs: An interpretation involving atoms and charge exchange collisions (open access)

Time-dependence ion charge state distributions of vacuum arcs: An interpretation involving atoms and charge exchange collisions

Experimentally observed charge state distributions are known to be higher at the beginning of each arc discharge. Up to know, this has been attributed to cathode surface effects in terms of changes of temperature, chemical composition and spot mode. Here it is shown that the initial decay of charge states of cathodic arc plasmas may at least in part due to charge exchange collisions of ions with neutrals that gradually fill the discharge volume. Sources of neutrals may include evaporated atoms from macroparticles and still-hot craters of previously active arc spots. More importantly, atoms are also produced by energetic condensation of the cathodic arc plasma. Self-sputtering is significant when ions impact with near-normal angle of incidence, and ions have low sticking probability when impacting at oblique angle of incidence. Estimates show that the characteristic time for filling the near-cathode discharge volume agrees well with the charge state decay time, and the likelihood of charge exchange is reasonably large to be taken into account.
Date: August 27, 2004
Creator: Anders, Andre
Object Type: Article
System: The UNT Digital Library