Beam Dynamics Studies Of Parallel-Bar Deflecting Cavities,
2011
Old Dominion University
Beam Dynamics Studies Of Parallel-Bar Deflecting Cavities, S. Ahmed, G. A. Krafft, K. Deitrick, Subashini U. De Silva, Jean R. Delayen, M. Spata, M. Tiefenback, A. Hofler, K. Beard
Physics Faculty Publications
We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the …
Fundamental And Hom Coupler Design Of The Superconducting Parallel-Bar Cavities,
2011
Old Dominion University
Fundamental And Hom Coupler Design Of The Superconducting Parallel-Bar Cavities, Subashini De Silva, Jean R. Delayen
Physics Faculty Publications
The superconducting parallel-bar cavity [1] is currently being considered as a deflecting system for the Jefferson Lab 12 GeV upgrade and as a crabbing cavity for a possible LHC luminosity upgrade. Currently the designs are optimized to achieve lower surface fields within the dimensional constraints for the above applications. A detailed analysis of the fundamental input power coupler design for the parallel-bar cavity is performed considering beam loading and the effects of microphonics. For higher beam loading the damping of the HOMs is vital to reduce beam instabilities generated due to the wake fields. An analysis of threshold impedances for …
Crab Crossing Schemes And Studies For Electron Ion Collider,
2011
Old Dominion University
Crab Crossing Schemes And Studies For Electron Ion Collider, S. Ahmed, Y. Derbenev, V. Morozov, A. Castilla, Geoffrey A. Krafft, B. Yunn, Subashini U. De Silva, Jean R. Delayen
Physics Faculty Publications
This report shows our progress in crab crossing consideration for future electron-ion collider envisioned at JLab. In this design phase, we are evaluating two crabbing schemes viz., the deflecting and dispersive. The mathematical formulations and lattice design for these schemes are discussed in this paper. Numerical simulations involving particle tracking through a realistic deflecting RF cavity and optics illustrate the desired crab tilt of 25 mrad for 1.35 MV. Evolution of beam propagation are shown which provides the physical insight of the crabbing phenomenon.
Analysis Of Hom Properties Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities,
2011
Old Dominion University
Analysis Of Hom Properties Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities, Subashini De Silva, Jean R. Delayen
Physics Faculty Publications
The superconducting parallel-bar cavity is currently being considered for a number of deflecting and crabbing applications due to improved properties and compact design geometries. The 499 MHz deflecting cavity proposed for the Jefferson Lab 12 GeV upgrade and the 400 MHz crab cavity for the proposed LHC luminosity upgrade are two of the major applications. For high current applications the higher order modes must be damped to acceptable levels to eliminate any beam instabilities. The frequencies and R/Q of the HOMs and mode separation are evaluated and compared for different parallel-bar cavity designs.
Mechanical Study Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities,
2011
Old Dominion University
Mechanical Study Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities, Hyekyoung Park, Jean R. Delayen, Subashini De Silva
Physics Faculty Publications
The superconducting parallel-bar deflecting/crabbing cavities have improved properties compared to conventional cavity structures. It is currently being considered for number of applications. The mechanical design analysis is performed on two designs of the 499 MHz parallel-bar deflecting cavity for the Jefferson Lab 12 GeV upgrade. The main purpose of the mechanical study is to examine the structural stability of the cavities under the operating conditions in the accelerators. The study results will suggest the need for additional structural strengthening. Also the study results will help to develop a concept of the tuning method. If the cavity is to be installed …
Design Of Superconducting Spoke Cavities For High-Velocity Applications,
2011
Old Dominion University
Design Of Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, Subashini De Silva, C. S. Hopper
Physics Faculty Publications
Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β0 ~ 0.15 to β0 ~ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β0 = 0.8 and β0 = 1.
Design Of Superconducting Parallel Bar Deflecting/Crabbing Cavities,
2011
Old Dominion University
Design Of Superconducting Parallel Bar Deflecting/Crabbing Cavities, Jean R. Delayen, Subashini De Silva
Physics Faculty Publications
The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.
Crab Crossing Consideration For Meic,
2011
Old Dominion University
Crab Crossing Consideration For Meic, S. Ahmed, Y. Derbenev, Geoffrey A. Krafft, Y. Zhang, Subashini De Silva, Jean R. Delayen, A. Castilla
Physics Faculty Publications
Crab crossing of colliding electron and ion beams is essential for accommodating the high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report the possible crabbing schemes and requirements for both electron and proton beams.
Multipacting Analysis Of The Superconducting Parallel-Bar Cavity,
2011
Old Dominion University
Multipacting Analysis Of The Superconducting Parallel-Bar Cavity, Subashini De Silva, Jean R. Delayen
Physics Faculty Publications
The superconducting parallel-bar cavity [1] is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.
Design Of Low-Frequency Superconducting Spoke Cavities For High-Velocity Applications,
2011
Old Dominion University
Design Of Low-Frequency Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, C. S. Hopper, R. G. Olave
Physics Faculty Publications
Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of 325 and 352 MHz spoke cavities optimized for β=0.8 and β=1.
Measurement System For High Pressure Characterizations Of Materials,
2010
University of Nevada, Las Vegas
Measurement System For High Pressure Characterizations Of Materials, Matthew K. Jacobsen
UNLV Theses, Dissertations, Professional Papers, and Capstones
Thermoelectric materials have long been investigated for possible use as power sources. This application was recently put to use in the Voyager space program, powering the deep space probes. Despite the usefulness of these materials, the use of pressure to investigate the material properties has only recently become interesting. As such, the work in this document was to developing a system for concurrently measuring the necessary properties. This system is capable of measuring the electrical resistivity, thermal conductivity, and Seebeck coefficient in the pressure range from 0 - 10 GPa. The results for zinc, almandine garnet, and nickel are presented …
A Comprehensive Rocket And Radar Study Of Midlatitude Spread F,
2010
Embry-Riddle Aeronautical University
A Comprehensive Rocket And Radar Study Of Midlatitude Spread F, G.D. Earle, P. Bhanja, P.A. Roddy, C.M. Swenson, Aroh Barjatya, Et Al.
Publications
An instrumented sounding rocket launched from Wallops Island Virginia has flown through a midlatitude spread F (MSF) event in conjunction with simultaneous ionosonde, HF radar, and 244 MHz scintillation observations from the ground. The in situ measurements include the electric field, horizontal neutral wind, and plasma density within the spread F region. The ground‐based HF radar measurements of wave signatures in the bottomside F region ledge reveal the presence of waves propagating to the north and northwest prior to and during the spreading event. The periods of these bottomside waves range from 16 to 60 min, and they are shown …
Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells,
2010
Old Dominion University
Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells, Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Pavel Anzenbacher, Mikhail Zamkov
Electrical & Computer Engineering Faculty Publications
We report on pulsed laser deposition of graphite onto flexible plastic and conductive glass substrates for use as a counter electrode in dye-sensitized solar cells. The efficiency of as-prepared graphite electrodes was tested using CdS-sensitized solar cell architecture resulting in external quantum efficiency comparable to that of conventional platinum counter electrodes. This work highlights the possibility of using pulsed laser deposited graphite as a low-cost alternative to platinum, which could be fabricated both on flexible and rigid substrates.
Development Of Acrylamide Based Photopolymer For Full Colour Display Holography,
2010
Technological University Dublin
Development Of Acrylamide Based Photopolymer For Full Colour Display Holography, Chakrapani Meka
Doctoral
Holography is a firmly established discipline that can be used as a tool for scientific and engineering studies and as a display medium as well. Until now both silver halide photographic emulsions (SHPE) and dichromated gelatine (DCG) have been the most common materials used for high efficiency full colour reflection hologram recording. However, these materials require wet chemical processing for developing the holograms which is laborious and costly from the point of view of commercial applications. Self-developing photopolymers such as acrylamide based photopolymer (ABP) which do not require development are the ideal choice for real-time recording and reconstruction of holograms. …
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles,
2010
University of South Carolina - Columbia
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Faculty Publications
No abstract provided.
Energetyka Niskoemisyjna,
2010
Wroclaw University of Technology
Energetyka Niskoemisyjna, Wojciech M. Budzianowski
Wojciech Budzianowski
No abstract provided.
Structural, Magnetic, And Defect Properties Of Co-Pt-Type Magnetic-Storage Alloys: Density-Functional Theory Study Of Thermal Processing Effects,
2010
University of Illinois at Urbana-Champaign
Structural, Magnetic, And Defect Properties Of Co-Pt-Type Magnetic-Storage Alloys: Density-Functional Theory Study Of Thermal Processing Effects, Aftab Alam, Brent Kraczek, Duane D. Johnson
Duane D. Johnson
Using an optimized-basis Korringa-Kohn-Rostoker-coherent-potential approximation method, we calculate formation enthalpies ΔEf, structural, and magnetic properties of paramagnetic (PM) and ferromagnetic, disordered A1 and ordered L10 CoPt, FePd, and FePt systems that are of interest for high-density magnetic-recording media. To address processing effects, we focus on the point defects that dictate thermal properties and planar defects (e.g., c domain and antiphase boundaries) which can serve as pinning centers for magnetic domains and affect storage properties. We determine bulk Curie (Tc) and order-disorder (To-d) transition temperatures within 4% of observed values, and estimates for nanoparticles. Planar-defect energies γhklx show that the favorable …
Nonlinear Observers For Human-In-The-Loop Control Systems,
2010
Embry-Riddle Aeronautical University - Daytona Beach
Nonlinear Observers For Human-In-The-Loop Control Systems, Samuel Kitchen Mckinley
Master's Theses - Daytona Beach
The development of models for a human-in-the-loop with hardware is an area of ongoing research. The ability to simulate a human-in-the-loop with hardware provides a platform for better understanding the dynamics of human and machine cognition. A human-in-the-loop model provides information that can be used to design more efficient human interfaces and smarter autonomous assistant controllers. This can make a complex task such as flying an aircraft safer and more accessible. This thesis explores different possibilities for human operator models to be modeled in the loop with a vehicle. A human is modeled as a linear state feedback controller in …
Boron Carbide Based Solid State Neutron Detectors: The Effects Of Bias And Time Constant On Detection Efficiency,
2010
University of Nebraska-Lincoln
Boron Carbide Based Solid State Neutron Detectors: The Effects Of Bias And Time Constant On Detection Efficiency, Nina Hong, John Mullins, Keith Foreman, Shireen Adenwalla
Shireen Adenwalla Papers
Neutron detection in thick boron carbide(BC)/n-type Si heterojunction diodes shows a threefold increase in efficiency with applied bias and longer time constants. The improved efficiencies resulting from long time constants have been conclusively linked to the much longer charge collection times in the BC layer. Neutron detection signals from both the p-type BC layer and the n-type Si side of the heterojunction diode are observed, with comparable efficiencies. Collectively, these provide strong evidence that the semiconducting BC layer plays an active role in neutron detection, both in neutron capture and in charge generation and collection.
Construction And Enhancement Of Stereo Vacuum Tube Amplifier With Precision Machined Enclosure,
2010
California Polytechnic State University - San Luis Obispo
Construction And Enhancement Of Stereo Vacuum Tube Amplifier With Precision Machined Enclosure, Nikolaus (Nik) Glazar
Physics
The purpose of this project was to build a high fidelity tube amplifier from a kit, and machine a beautiful enclosure to house the electronics. Improvements were made to the circuit, and the amplifier was then tested for audio performance.
