Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers,
2012
California Polytechnic State University - San Luis Obispo
Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers, Keith Gresiak
Physics
No abstract provided.
Ion Acceleration In A Helicon Source Due To The Self-Bias Effect,
2012
College of Saint Benedict/Saint John's University
Ion Acceleration In A Helicon Source Due To The Self-Bias Effect, Matt Wiebold, Yung-Ta Sung, John E. Scharer
Physics Faculty Publications
Time-averaged plasma potential differences up to 165 V over several hundred Debye lengths are observed in low pressure (pn < 1 mTorr) expanding argon plasmas in the Madison Helicon eXperiment (MadHeX). The potential gradient leads to ion acceleration greater than that predicted by ambipolar expansion, exceeding Ei≈7 kTe in some cases. RF power up to 500 W at 13.56 MHz is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field, adjustable up to 1 kG. A retarding potential analyzer (RPA) measures the ion energy distribution function (IEDF) and a swept emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, …
Magnetic Field Amplification In Electron Phase-Space Holes And Related Effects,
2012
Dartmouth College
Magnetic Field Amplification In Electron Phase-Space Holes And Related Effects, R. A. Treumann, W. Baumjohann
Dartmouth Scholarship
No abstract provided.
Case Studies In Many-Body Physics,
2012
Old Dominion University
Case Studies In Many-Body Physics, Ana Samolov
Physics Theses & Dissertations
The many-body problem refers to any physical problem made of more than two interacting particles. With increasing number of particles in a system, their coupling and entanglement becomes more complex, and there is no general analytic solution even for a three-body classical or quantum systems. However, some of the most fascinating phenomena in nature are products of collective effects. Therefore, significant efforts have been made in both experiment and theory to unravel some specific many-body problems. If we look at still unanswered physics questions we see that for most of these problems addressing the many-body interactions is a key issue. …
Collisional Dynamics, Lasing And Stimulated Raman Scattering In Optically Pumped Cesium And Potassium Vapors,
2012
Air Force Institute of Technology
Collisional Dynamics, Lasing And Stimulated Raman Scattering In Optically Pumped Cesium And Potassium Vapors, Kirk C. Brown
Theses and Dissertations
This dissertation explores collisional dynamics, lasing and stimulated Raman scattering in cesium and potassium vapors. The spin orbit mixing and quenching cross sections of several buffer gas species are measured. The ne-structure mixing cross sections for He, CH4 and C2H6 are 14±3, 35±6 and 73±10 °A2, respectively. The 2P3/2 state is quenched more rapidly than the 2P1/2 state. A pulsed blue laser operating via direct excitation of the cesium 72P3/2 state is demonstrated. A theoretical model is extended and compared with experimental results. The maximum output …
Spectral And Spatial Coherent Emission Of Thermal Radiation From Metal-Semiconductor Nanostructures,
2012
Air Force Institute of Technology
Spectral And Spatial Coherent Emission Of Thermal Radiation From Metal-Semiconductor Nanostructures, Shane N. Mcconnell
Theses and Dissertations
The spectral and spatial radiative properties of coherent thermal emission in the mid- and far-IR through the use of micro and nano-structured metal-semiconductor materials were designed and demonstrated experimentally. Using an implementation of the Rigorous Coupled Wave Analysis and Computer Simulation Technology (CST), two structures were designed to selectively emit at mid- and far-IR wavelengths, a 1-D truncated multilayer resonator and a 3-D hybrid photonic crystal (PC)-multilayer. A High Impulse Power Magnetron Sputtering (HIPIMS) deposition technique was used to fabricate two silver-germanium-silver (Ag-Ge-Ag) resonating structures with layer thicknesses of 6-240-160 nm for one sample and 6-700-200 nm for the other. …
Preconditioning Visco-Resistive Mhd For Tokamak Plasmas,
2012
Southern Methodist University
Preconditioning Visco-Resistive Mhd For Tokamak Plasmas, Daniel R. Reynolds, Ravi Samtaney, Hilari C. Tiedeman
Mathematics Research
No abstract provided.
Quantitative Study Of Spin-Flip Co-Tunneling Transport In A Quantum Dot,
2012
Xavier University - Cincinnati
Quantitative Study Of Spin-Flip Co-Tunneling Transport In A Quantum Dot, S. Herbert, T-M. Liu, A. N. Ngo
Faculty Scholarship
No abstract provided.
Observation And Identification Of Metastable Excited
States In Ultrafast Laser-Ionized Pyridine,
2012
University of Nebraska-Lincoln
Observation And Identification Of Metastable Excited States In Ultrafast Laser-Ionized Pyridine, David B. Foote, Timothy D. Scarborough, Cornelis J. Uiterwaal
C.J.G.J. Uiterwaal Publications
We report on the fragmentation of ionized pyridine (C5H5N) molecules by focused 50 fs, 800 nm laser pulses. Such ionization produces several metastable ionic states that fragment within the field-free drift region of a reflectron- type time of flight mass spectrometer, with one particular metastable dissociation being the leading fragmentation process. Because the time of flight is no longer dependent in a simple way on the mass of the ion, the metastable decay is manifested as an unfocused peak on the mass spectrum that appears at a time of flight not corresponding to an integer mass. …
Contamination Effects On Fixed-Bias Langmuir Probes,
2012
Christian-Albrechts-Universität zu Kiel
Contamination Effects On Fixed-Bias Langmuir Probes, C.T. Steigies, A. Barjatya
Publications
Langmuir probes are standard instruments for plasma density measurements on many sounding rockets. These probes can be operated in swept-bias as well as in fixed-bias modes. In swept-bias Langmuir probes, contamination effects are frequently visible as a hysteresis between consecutive up and down voltage ramps. This hysteresis, if not corrected, leads to poorly determined plasma densities and temperatures. With a properly chosen sweep function, the contamination parameters can be determined from the measurements and correct plasma parameters can then be determined. In this paper, we study the contamination effects on fixed-bias Langmuir probes, where no hysteresis type effect is seen …
Assessing The Feasibility Of Cosmic-Ray Acceleration By Magnetic Turbulence At The Magnetic Center,
2012
Xavier University - Cincinnati
Assessing The Feasibility Of Cosmic-Ray Acceleration By Magnetic Turbulence At The Magnetic Center, M. Fatuzzo, F. Melia
Faculty Scholarship
No abstract provided.
Multipacting Analysis Of High-Velocity Superconducting Spoke Resonators,
2012
Old Dominion University
Multipacting Analysis Of High-Velocity Superconducting Spoke Resonators, C. S. Hopper, J. R. Delayen
Physics Faculty Publications
Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.
Superconducting Spoke Cavities For Electron And High-Velocity Proton Linacs,
2012
Old Dominion University
Superconducting Spoke Cavities For Electron And High-Velocity Proton Linacs, J. R. Delayen
Physics Faculty Publications
Spoke resonantors are currently under development for many proton machines but these structures are also considered for high beta electron linacs as well. These structures compare well to traditional elliptical cavities.
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei,
2012
Old Dominion University
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein
Physics Faculty Publications
We have measured the nuclear transparency of the incoherent diffractive A( e , e ′ ρ0 ) process in 12C and 56Fe targets relative to 2H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ0 ʼs on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (lc), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q2). While the transparency for both 12C and 56Fe …
Beam Dynamics Studies For Transverse Electromagnetic Mode Type Rf Deflectors,
2012
Old Dominion University
Beam Dynamics Studies For Transverse Electromagnetic Mode Type Rf Deflectors, Shahid Ahmed, Geoffrey A. Krafft, Kirsten Deitrick, Subashini U. De Silva, Jean R. Delayen, Mike Spata, Michael Tiefenback, Alicia Hofler, Kevin Beard
Physics Faculty Publications
We have performed three-dimensional simulations of beam dynamics for transverse electromagnetic mode (TEM) type rf deflectors: normal and superconducting. The compact size of these cavities as compared to the 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 six 2-cell normal conducting cavities or a single cell superconducting structure is enough to produce the required vertical displacement at the target point. Both the normal and superconducting structures show very small emittance dilution due to the …
Electronic Detection Of Ultra Cold Neutral Plasma,
2012
Colby College
Electronic Detection Of Ultra Cold Neutral Plasma, Nirakar Poudel
Honors Theses
The project was started with an objective to investigate the effect of radio fre- quency absorption in Ultra Cold Neutral Plasmas (UNPs). The plasma oscillation is density dependent and can be excited by using external radio frequency field. A homodyne circuit is used to detect direct absorption of the radio frequency waves. The radio frequency waves are applied to conducting meshes which lie on either side of the plasma. The meshes are effectively a capacitor, which together with inherent circuit resistance constitute a high pass filter. A small part of the gain and phase shift of the filter depend on …
Electroluminescence Studies On Longwavelength Indium Arsenide Quantum Dot Microcavities Grown On Gallium Arsenide,
2011
Air Force Institute of Technology
Electroluminescence Studies On Longwavelength Indium Arsenide Quantum Dot Microcavities Grown On Gallium Arsenide, John C. Ramsey
Theses and Dissertations
A comprehensive study of the electroluminescence of four GaAs/AlGaAs microcavity devices with InAs/GaInAs quantum dot active regions emitting near 1.3 µm was conducted. The four molecular beam epitaxial grown samples with AlAs oxide aperture confinement layers were fabricated, characterized, and optically modeled. Optical power transmission of the samples was modeled using Matlab and compared with measured transmission data. Resonant cavity light emitting diodes (RCLEDs) and three vertical cavity surface emitting laser (VCSEL) samples were fabricated and electro-optically characterized over a range of injection currents and temperatures. Devices achieved continuous wave room temperature lasing at 1.28 µm with an output power …
Kinetics Of The Electrical Discharge Pumped Oxygen-Iodine Laser,
2011
Air Force Institute of Technology
Kinetics Of The Electrical Discharge Pumped Oxygen-Iodine Laser, Matthew A. Lange
Theses and Dissertations
A systematic study of microwave discharges at 2.45 GHz has been performed through the pressure range of sustainable electric discharges in pure oxygen flows of 2 to 10 Torr. A corresponding study of 13.56 MHz has also been performed at pressures of 2, 4, and 7 Torr. Optical emissions from O2(a 1Δ), O2(b 1Σ), and O-atoms have been measured from the center of a μ-wave discharge. Discharge residence times from 0.1 to 5 ms have been reported. The O2(b 1Σ) emissions, with a spectral resolution of 0.01 nm, have been used to measure the temperature of the gas, which typically …
Dc Pulsed Atmospheric Pressure Plasma Jet Image Information,
2011
University College Dublin
Dc Pulsed Atmospheric Pressure Plasma Jet Image Information, Denis P. Dowling, F T. O'Neill, Vladimir Milosavljevic, Victor J. Law
Articles
This paper presents optical imaging and optical emission spectroscopy (OES) data of an atmospheric-pressure plasma jet. It is shown how the visual information and OES information of the air discharge are related as the blown arc extends from the nozzle (2-4 mm) with a molecular nitrogen rotational temperature on the order of 1700 K and the flowing afterglow beyond this region is dominated by the cooler (300-K) NO-O chemiluminescent reaction that produces NO2 species.
Magnetic Field Mapping In The Plasmoid Thruster Experiment (Ptx),
2011
University of Alabama in Huntsville
Magnetic Field Mapping In The Plasmoid Thruster Experiment (Ptx), Coby W. Mccolgin
Von Braun Symposium Student Posters
No abstract provided.
