AVNG as a Test Case for Cooperative Design (open access)

AVNG as a Test Case for Cooperative Design

Designing a measurement system that might be used in a nuclear facility is a challenging, if not daunting, proposition. The situation is made more complicated when the system needs to be designed to satisfy the disparate requirements of a monitoring and a host party - a relationship that could prove to be adversarial. The cooperative design of the elements of the AVNG (Attribute Verification with Neutrons and Gamma Rays) system served as a crucible that exercised the possible pitfalls in the design and implementation of a measurement system that could be used in a host party nuclear facility that satisfied the constraints of operation for both the host and monitoring parties. Some of the issues that needed to be addressed in the joint design were certification requirements of the host party and the authentication requirements of the monitoring party. In this paper the nature of the problem of cooperative design will be introduced. The details of cooperative design revolve around the idiosyncratic nature of the adversarial relationship between the parties involved in a possible measurement regime, particularly if measurements on items that may contain sensitive information are being pursued. The possibility of an adversarial interaction is more likely if an …
Date: May 21, 2010
Creator: Luke, S J
Object Type: Article
System: The UNT Digital Library
Self-guided Laser Wakefield Acceleration Beyond 1 GeV using Ionization-induced Injection (open access)

Self-guided Laser Wakefield Acceleration Beyond 1 GeV using Ionization-induced Injection

None
Date: April 21, 2010
Creator: Clayton, C. E.; Ralph, J. E.; Albert, F.; Fonseca, R. A.; Glenzer, S. H.; Joshi, C. et al.
Object Type: Article
System: The UNT Digital Library
Shack-Hartmann Wavefront Sensing Performance Evaluation for Active Correction of the Large Synoptic Survey Telescope (LSST) (open access)

Shack-Hartmann Wavefront Sensing Performance Evaluation for Active Correction of the Large Synoptic Survey Telescope (LSST)

None
Date: July 21, 2010
Creator: Baker, K L & Seppala, L
Object Type: Article
System: The UNT Digital Library
Extreme ultraviolet mask substrate surface roughness effects on lithography patterning (open access)

Extreme ultraviolet mask substrate surface roughness effects on lithography patterning

In extreme ultraviolet lithography exposure systems, mask substrate roughness induced scatter contributes to LER at the image plane. In this paper, the impact of mask substrate roughness on image plane speckle is explicitly evaluated. A programmed roughness mask was used to study the correlation between mask roughness metrics and wafer plane aerial image inspection. We find that the roughness measurements by top surface topography profile do not provide complete information on the scatter related speckle that leads to LER at the image plane. We suggest at wavelength characterization by imaging and/or scatter measurements into different frequencies as an alternative for a more comprehensive metrology of the mask substrate/multilayer roughness effects.
Date: June 21, 2010
Creator: George, Simi; Naulleau, Patrick; Salmassi, Farhad; Mochi, Iacopo; Gullikson, Eric; Goldberg, Kenneth et al.
Object Type: Article
System: The UNT Digital Library
Dynamics of Longitudinal Phase-Space Modulations in an rf Compressor for Electron Beams (open access)

Dynamics of Longitudinal Phase-Space Modulations in an rf Compressor for Electron Beams

Free Electron Lasers (FELs) operating in the UV or x-ray radiation spectrum require peak beam currents that are generally higher than those obtainable by present electron sources, thus making bunch compression necessary. Compression, however, may heighten the effects of collective forces and degrade the beam quality. In this paper they provide a framework for investigating some of these effects in rf compressors by focusing on the longitudinal dynamics of small-amplitude density perturbations, which have the potential to cause the disruptive appearance of the so-called microbunching instability. They develop a linear theory valid for low-to-moderate compression factors under the assumption of a 1D impedance model of longitudinal space charge and provide validation against macroparticle simulations.
Date: May 21, 2010
Creator: Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M. & Vaccarezza, C.
Object Type: Article
System: The UNT Digital Library
Sludge Batch 6 Acceptance Evaluation:  Radionuclide Concentrations in Tank 51 sb6 Qualification Sample Prepared at SRNL (open access)

Sludge Batch 6 Acceptance Evaluation: Radionuclide Concentrations in Tank 51 sb6 Qualification Sample Prepared at SRNL

Presented in this report are radionuclide concentrations required as part of the program of qualifying Sludge Batch Six (SB6) for processing in the Defense Waste Processing Facility (DWPF). The SB6 material is currently in Tank 51 being washed and prepared for transfer to Tank 40. The acceptance evaluation needs to be completed prior to the transfer of the material in Tank 51 to Tank 40. The sludge slurry in Tank 40 has already been qualified for DWPF and is currently being processed as SB5. The radionuclide concentrations were measured or estimated in the Tank 51 SB6 Qualification Sample prepared at Savannah River National Laboratory (SRNL). This sample was prepared from the three liter sample of Tank 51 sludge slurry (HTF-51-09-110) taken on October 8, 2009. The sample was delivered to SRNL where it was initially characterized in the Shielded Cells. Under the direction of the Liquid Waste Organization it was then modified by eight washes, nine decants, an addition of Pu from Canyon Tank 16.3, and an addition of NaNO{sub 2}. This final slurry now has a composition expected to be similar to that of the slurry in Tank 51 after final preparations have been made for transfer of that …
Date: May 21, 2010
Creator: Bannochie, C.; Bibler, N. & Diprete, D.
Object Type: Report
System: The UNT Digital Library
Iterative Self-Dual Reconstruction on Radar Image Recovery (open access)

Iterative Self-Dual Reconstruction on Radar Image Recovery

Imaging systems as ultrasound, sonar, laser and synthetic aperture radar (SAR) are subjected to speckle noise during image acquisition. Before analyzing these images, it is often necessary to remove the speckle noise using filters. We combine properties of two mathematical morphology filters with speckle statistics to propose a signal-dependent noise filter to multiplicative noise. We describe a multiscale scheme that preserves sharp edges while it smooths homogeneous areas, by combining local statistics with two mathematical morphology filters: the alternating sequential and the self-dual reconstruction algorithms. The experimental results show that the proposed approach is less sensitive to varying window sizes when applied to simulated and real SAR images in comparison with standard filters.
Date: May 21, 2010
Creator: Martins, Charles; Medeiros, Fatima; Ushizima, Daniela; Bezerra, Francisco; Marques, Regis & Mascarenhas, Nelson
Object Type: Article
System: The UNT Digital Library
Bimetallic Lithium Borohydrides Toward Reversible Hydrogen Storage (open access)

Bimetallic Lithium Borohydrides Toward Reversible Hydrogen Storage

Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic borohydrides, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species.
Date: October 21, 2010
Creator: Au, M.
Object Type: Article
System: The UNT Digital Library
Masked Photocathode for Photoinjector (open access)

Masked Photocathode for Photoinjector

In this research note, we propose a scheme to insert a photocathode inside a photoinjector for generating high brightness electron beam. Instead of mounting the photocathode onto the electrode, a masked electrode with small hole is used to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material very simple by rotating the photocathode behind the mask into the hole. This will significantly increase the usage lifetime of a photocathode. Furthermore, this also helps reduce the dark current or secondary electron emission from the photocathode. The hole on the mask also provides a transverse cut-off to the Gaussian laser profile which can be beneficial from the beam dynamics point of view.
Date: January 21, 2010
Creator: Qiang, Ji
Object Type: Report
System: The UNT Digital Library
Ganges Valley Aerosol Experiment: Science and Operations Plan (open access)

Ganges Valley Aerosol Experiment: Science and Operations Plan

The Ganges Valley region is one of the largest and most rapidly developing sections of the Indian subcontinent. The Ganges River, which provides the region with water needed for sustaining life, is fed primarily by snow and rainfall associated with Indian summer monsoons. Impacts of changes in precipitation patterns, temperature, and the flow of the snow-fed rivers can be immense. Recent satellite-based measurements have indicated that the upper Ganges Valley has some of the highest persistently observed aerosol optical depth values. The aerosol layer covers a vast region, extending across the Indo-Gangetic Plain to the Bay of Bengal during the winter and early spring of each year. The persistent winter fog in the region is already a cause of much concern, and several studies have been proposed to understand the economic, scientific, and societal dimensions of this problem. During the INDian Ocean EXperiment (INDOEX) field studies, aerosols from this region were shown to affect cloud formation and monsoon activity over the Indian Ocean. This is one of the few regions showing a trend toward increasing surface dimming and enhanced mid-tropospheric warming. Increasing air pollution over this region could modify the radiative balance through direct, indirect, and semi-indirect effects associated with …
Date: June 21, 2010
Creator: Kotamarthi, V. R.
Object Type: Report
System: The UNT Digital Library
Simulations of Small-Pore Microchannel Plates for Fast Gated X-ray Imaging and Spectroscopy of High-Energy Density Plasmas (open access)

Simulations of Small-Pore Microchannel Plates for Fast Gated X-ray Imaging and Spectroscopy of High-Energy Density Plasmas

This poster describes work done at National Security Technologies, LLC (NSTec), and Sandia National Laboratories (SNL) over the past several years on the design and characterization of microchannel plate (MCP)-based fast-gated x-ray imagers for use on the SNL Z machine. These cameras use 10-micron-pore MCPs similar to the type used for spectroscopy and imaging applications at other facilities. To aid in the understanding of MCP behavior, we have developed a Monte Carlo simulation model for prediction of MCP response. The code contains a detailed physical model of the electron cascade and amplification process of the MCP that includes energy conservation for the secondary electrons, the effects of elastic scattering of low-energy electrons from the channel wall, and gain saturation mechanisms from wall charging and space charge. Our model can simulate MCP response for both static and pulsed voltage waveforms. Excellent agreement between the Monte Carlo simulations and laboratory measurements has been achieved. Here, we apply our simulation model to 2-micron-pore MCPs, which, while readily available from a variety of vendors, are not used in imaging applications. We investigated the DC and pulsed gain characteristics of such an MCP, with particular emphasis on dynamic range, temporal response, and spatial resolution. The …
Date: June 21, 2010
Creator: Craig A. Kruschwitz, Ming Wu, Greg Rochau
Object Type: Article
System: The UNT Digital Library
Energy Efficiency Services Sector: Workforce Size and Expectations for Growth (open access)

Energy Efficiency Services Sector: Workforce Size and Expectations for Growth

None
Date: October 21, 2010
Creator: Goldman, Charles; Fuller, Merrian C.; Stuart, Elizabeth; Peters, Jane S.; McRae, Marjorie; Albers, Nathaniel et al.
Object Type: Report
System: The UNT Digital Library
THE USE OF DI WATER TO MITIGATE DUSTING FOR ADDITION OF DWPF FRIT TO THE SLURRY MIX EVAPORATOR (open access)

THE USE OF DI WATER TO MITIGATE DUSTING FOR ADDITION OF DWPF FRIT TO THE SLURRY MIX EVAPORATOR

The Defense Waste Processing Facility (DPWF) presently is in the process to determine means to reduce water utilization in the Slurry Mix Evaporator (SME) process, thus reducing effluent and processing times. The frit slurry addition system mixes the dry frit with water, yielding approximately a 50 weight percent slurry containing frit and the other fraction water. This slurry is discharged into the SME and excess water is removed via boiling. To reduce this water load to the SME, DWPF has proposed using a pneumatic system in conveying the frit to the SME, in essence a dry delivery system. The problem associated with utilizing a dry delivery system with the existing frit is the generation of dust when discharged into the SME. The use of water has been shown to be effective in the mining industry as well in the DOE complex to mitigate dusting. The method employed by SRNL to determine the quantity of water to mitigate dusting in dry powders was effective, between a lab and bench scale tests. In those tests, it was shown that as high as five weight percent (wt%) of water addition was required to mitigate dust from batches of glass forming minerals used by …
Date: July 21, 2010
Creator: Hansen, E.
Object Type: Report
System: The UNT Digital Library
Probing Radiation Damage in Plutonium Alloys with Multiple Measurement Techniques (open access)

Probing Radiation Damage in Plutonium Alloys with Multiple Measurement Techniques

A material subjected to radiation damage will usually experience changes in its physical properties. Measuring these changes in the physical properties provides a basis to study radiation damage in a material which is important for a variety of real world applications from reactor materials to semiconducting devices. When investigating radiation damage, the relative sensitivity of any given property can vary considerably based on the concentration and type of damage present as well as external parameters such as the temperature and starting material composition. By measuring multiple physical properties, these differing sensitivities can be leveraged to provide greater insight into the different aspects of radiation damage accumulation, thereby providing a broader understanding of the mechanisms involved. In this report, self-damage from {alpha}-particle decay in Pu is investigated by measuring two different properties: magnetic susceptibility and resistivity. The results suggest that while the first annealing stage obeys second order chemical kinetics, the primary mechanism is not the recombination of vacancy-interstitial close pairs.
Date: April 21, 2010
Creator: McCall, S K; Fluss, M J & Chung, B W
Object Type: Article
System: The UNT Digital Library
SciDAC's Earth System Grid Center for Enabling Technologies Semi-Annual Progress Report for the Period October 1, 2009 through March 31, 2010 (open access)

SciDAC's Earth System Grid Center for Enabling Technologies Semi-Annual Progress Report for the Period October 1, 2009 through March 31, 2010

This report summarizes work carried out by the ESG-CET during the period October 1, 2009 through March 31, 2009. It includes discussion of highlights, overall progress, period goals, collaborations, papers, and presentations. To learn more about our project, and to find previous reports, please visit the Earth System Grid Center for Enabling Technologies (ESG-CET) website. This report will be forwarded to the DOE SciDAC program management, the Office of Biological and Environmental Research (OBER) program management, national and international collaborators and stakeholders (e.g., the Community Climate System Model (CCSM), the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), the Climate Science Computational End Station (CCES), the SciDAC II: A Scalable and Extensible Earth System Model for Climate Change Science, the North American Regional Climate Change Assessment Program (NARCCAP), and other wide-ranging climate model evaluation activities).
Date: April 21, 2010
Creator: Williams, D. N.; Foster, I. T.; Middleton, D. E.; Ananthakrishnan, R.; Siebenlist, F.; Shoshani, A. et al.
Object Type: Report
System: The UNT Digital Library
Influence of molecular ordering on electrical and friction properties of omega-(trans-4-stilbene)alkylthiol self-assembled monolayers on Au (111) (open access)

Influence of molecular ordering on electrical and friction properties of omega-(trans-4-stilbene)alkylthiol self-assembled monolayers on Au (111)

The electrical and friction properties of omega-(trans-4-stilbene)alkylthiol self-assembled monolayers (SAMs) on Au(111) were investigated using atomic force microscopy (AFM) and near edge x-ray absorption fine structure spectroscopy (NEXAFS). The sample surface was uniformly covered with a molecular film consisting of very small grains. Well-ordered and flat monolayer islands were formed after the sample was heated in nitrogen at 120 oC for 1 h. While lattice resolved AFM images revealed a crystalline phase in the islands, the area between islands showed no order. The islands exhibit substantial reduction (50percent) in friction, supporting the existence of good ordering. NEXAFS measurements revealed an average upright molecular orientation in the film, both before and after heating, with a narrower tilt-angle distribution for the heated fim. Conductance-AFM measurements revealed a two orders of magnitude higher conductivity on the ordered islands than on the disordered phase. We propose that the conductance enhancement is a result of a better pi-pi stacking between the trans-stilbene molecular units as a result of improved ordering in islands.
Date: April 21, 2010
Creator: Qi, Yabing; Liu, Xiaosong; Hendriksen, B.L.M.; Navarro, V.; Park, Jeong Y.; Ratera, Imma et al.
Object Type: Article
System: The UNT Digital Library
Annual Radioactive Waste Tank Inspection Program 2009 (open access)

Annual Radioactive Waste Tank Inspection Program 2009

Aqueous radioactive wastes from Savannah River Site (SRS) separations and vitrification processes are contained in large underground carbon steel tanks. Inspections made during 2009 to evaluate these vessels and other waste handling facilities along with evaluations based on data from previous inspections are the subject of this report. The 2009 inspection program revealed that the structural integrity and waste confinement capability of the Savannah River Site waste tanks were maintained. All inspections scheduled per LWO-LWE-2008-00423, HLW Tank Farm Inspection Plan for 2009, were completed. All Ultrasonic measurements (UT) performed in 2009 met the requirements of C-ESG-00006, In-Service Inspection Program for High Level Waste Tanks, Rev. 1, and WSRC-TR-2002-00061, Rev.4. UT inspections were performed on Tank 29 and the findings are documented in SRNL-STI-2009-00559, Tank Inspection NDE Results for Fiscal Year 2009, Waste Tank 29. Post chemical cleaning UT measurements were made in Tank 6 and the results are documented in SRNL-STI-2009-00560, Tank Inspection NDE Results Tank 6, Including Summary of Waste Removal Support Activities in Tanks 5 and 6. A total of 6669 photographs were made and 1276 visual and video inspections were performed during 2009. Twenty-Two new leaksites were identified in 2009. The locations of these leaksites are documented …
Date: June 21, 2010
Creator: West, B. & Waltz, R.
Object Type: Report
System: The UNT Digital Library
Co-simulation of innovative integrated HVAC systems in buildings (open access)

Co-simulation of innovative integrated HVAC systems in buildings

Integrated performance simulation of buildings HVAC systems can help in reducing energy consumption and increasing occupant comfort. However, no single building performance simulation (BPS) tool offers sufficient capabilities and flexibilities to analyze integrated building systems and to enable rapid prototyping of innovative building and system technologies. One way to alleviate this problem is to use co-simulation, as an integrated approach to simulation. This article elaborates on issues important for co-simulation realization and discusses multiple possibilities to justify the particular approach implemented in the here described co-simulation prototype. The prototype is validated with the results obtained from the traditional simulation approach. It is further used in a proof-of-concept case study to demonstrate the applicability of the method and to highlight its benefits. Stability and accuracy of different coupling strategies are analyzed to give a guideline for the required coupling time step.
Date: June 21, 2010
Creator: Trcka, Marija; Hensena, Jan L.M. & Wetter, Michael
Object Type: Article
System: The UNT Digital Library
High Pressure Burn Rate Measurements on an Ammonium Perchlorate Propellant (open access)

High Pressure Burn Rate Measurements on an Ammonium Perchlorate Propellant

High pressure deflagration rate measurements of a unique ammonium perchlorate (AP) based propellant are required to design the base burn motor for a Raytheon weapon system. The results of these deflagration rate measurements will be key in assessing safety and performance of the system. In particular, the system may experience transient pressures on the order of 100's of MPa (10's kPSI). Previous studies on similar AP based materials demonstrate that low pressure (e.g. P < 10 MPa or 1500 PSI) burn rates can be quite different than the elevated pressure deflagration rate measurements (see References and HPP results discussed herein), hence elevated pressure measurements are necessary in order understand the deflagration behavior under relevant conditions. Previous work on explosives have shown that at 100's of MPa some explosives will transition from a laminar burn mechanism to a convective burn mechanism in a process termed deconsolidative burning. The resulting burn rates that are orders-of-magnitude faster than the laminar burn rates. Materials that transition to the deconsolidative-convective burn mechanism at elevated pressures have been shown to be considerably more violent in confined heating experiments (i.e. cook-off scenarios). The mechanisms of propellant and explosive deflagration are extremely complex and include both chemical, and …
Date: April 21, 2010
Creator: Glascoe, E A & Tan, N
Object Type: Report
System: The UNT Digital Library
Evaluation of Efficiency Activities in the Industrial Sector Undertaken in Response to Greenhouse Gas Emission Reduction Targets (open access)

Evaluation of Efficiency Activities in the Industrial Sector Undertaken in Response to Greenhouse Gas Emission Reduction Targets

The 2006 California Global Warming Solutions Act calls for reducing greenhouse gas (GHG) emissions to 1990 levels by 2020. Meeting this target will require action from all sectors of the California economy, including industry. The industrial sector consumes 25% of the energy used and emits 28% of the carbon dioxide (CO{sub 2}) produced in the state. Many countries around the world have national-level GHG reduction or energy-efficiency targets, and comprehensive programs focused on implementation of energy efficiency and GHG emissions mitigation measures in the industrial sector are essential for achieving their goals. A combination of targets and industry-focused supporting programs has led to significant investments in energy efficiency as well as reductions in GHG emissions within the industrial sectors in these countries. This project has identified program and policies that have effectively targeted the industrial sector in other countries to achieve real energy and CO{sub 2} savings. Programs in Ireland, France, The Netherlands, Denmark, and the UK were chosen for detailed review. Based on the international experience documented in this report, it is recommended that companies in California's industrial sector be engaged in a program to provide them with support to meet the requirements of AB32, The Global Warming Solution …
Date: May 21, 2010
Creator: Price, Lynn; de la Rue du Can, Stephane; Lu, Hongyou & Horvath, Arpad
Object Type: Report
System: The UNT Digital Library
DWPF COAL CARBON WASTE ACCEPTANCE CRITERIA LIMIT EVALUATION (open access)

DWPF COAL CARBON WASTE ACCEPTANCE CRITERIA LIMIT EVALUATION

A paper study was completed to assess the impact on the Defense Waste Processing Facility (DWPF)'s Chemical Processing Cell (CPC) acid addition and melter off-gas flammability control strategy in processing Sludge Batch 10 (SB10) to SB13 with an added Fluidized Bed Steam Reformer (FBSR) stream and two Salt Waste Processing Facility (SWPF) products (Strip Effluent and Actinide Removal Stream). In all of the cases that were modeled, an acid mix using formic acid and nitric acid could be achieved that would produce a predicted Reducing/Oxidizing (REDOX) Ratio of 0.20 Fe{sup +2}/{Sigma}Fe. There was sufficient formic acid in these combinations to reduce both the manganese and mercury present. Reduction of manganese and mercury are both necessary during Sludge Receipt and Adjustment Tank (SRAT) processing, however, other reducing agents such as coal and oxalate are not effective in this reduction. The next phase in this study will be experimental testing with SB10, FBSR, and both SWPF simulants to validate the assumptions in this paper study and determine whether there are any issues in processing these streams simultaneously. The paper study also evaluated a series of abnormal processing conditions to determine whether potential abnormal conditions in FBSR, SWPF or DWPF would produce melter …
Date: June 21, 2010
Creator: Lambert, D. & Choi, A.
Object Type: Report
System: The UNT Digital Library
How Many IVUs Can We Install Without Sacrificing 16-Ma Operation? (open access)

How Many IVUs Can We Install Without Sacrificing 16-Ma Operation?

In this note, the authors examine the following hypothetical scenario: replacing existing 8-mm gap chambers with an in-vacuum undulator (IVU) one by one until they hit the boundary condition of 16-mA single-bunch operation. This is a continuation of a previous technical note on the topics of IVUs. The authors evaluated the impedance of IVU for various gaps. The result showed that the present 8-mm gap chamber can be replaced by the 8.754-mm IVU while maintaining the same 16-mA operational current. The estimates in this note make certain simplifying assumptions bearing on the effectiveness of nonlinear tapers. Subsequent evaluation of the effect of such tapers for APS parameters has cst considerable doubt on their usefulness. This results from the fact that APS has a fairly short electron bunch compared to the vacuum chamber dimensions. Investigation of other methods to decrease the impedance is on-going.
Date: January 21, 2010
Creator: Chae, Y.-C. & (APS), Accelerator Systems Division
Object Type: Report
System: The UNT Digital Library
Automated detection and analysis of particle beams in laser-plasma accelerator simulations (open access)

Automated detection and analysis of particle beams in laser-plasma accelerator simulations

Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread in momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of …
Date: May 21, 2010
Creator: Ushizima, Daniela Mayumi; Geddes, Cameron G.; Cormier-Michel, Estelle; Bethel, E. Wes; Jacobsen, Janet; Prabhat et al.
Object Type: Book
System: The UNT Digital Library
Development of a Spatially Resolving X-Ray Crystal Spectrometer (XCS) for Measurement of Ion-Temperature (Ti) and Rotation-Velocity (v) Profiles in ITER (open access)

Development of a Spatially Resolving X-Ray Crystal Spectrometer (XCS) for Measurement of Ion-Temperature (Ti) and Rotation-Velocity (v) Profiles in ITER

Imaging XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, Fe) with ~7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a PPPL-MIT instrument on Alcator C-Mod, uses a spherically bent crystal and 2d x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. Measurement of many spatial chords permits tomographic inversion for inference of local parameters. The instrument design, predictions of performance, and results from C-Mod will be presented.
Date: May 21, 2010
Creator: Hill, K. W.; Delgado-Aprico, L.; Johnson, D.; Feder, R.; Beiersdorfer, P.; Dunn, J. et al.
Object Type: Report
System: The UNT Digital Library