Plasma and Beam Physics Commons™

All Articles in Plasma and Beam Physics

438 full-text articles. Page 1 of 14.

2017 California Polytechnic State University, San Luis Obispo

Improvements For The T0c+ Geometry Of The Fast Interaction Trigger (Fit) Upgrade To Alice At The Cern Lhc, Noah Miller

Physics

The purpose of the ALICE experiment at CERN is to investigate the properties of the strongly interacting quark-gluon plasma formed in the high-energy collisions of lead nuclei in the CERN Large Hadron Collider. ALICE has been collecting data since 2009. The upcoming upgrade of the CERN LHC injectors during 2019-20 will boost the luminosity and the collision rate beyond the design parameters for several of the key ALICE detectors including the forward trigger detectors. The new Fast Interaction Trigger (FIT) will enable ALICE to discriminate beam-beam interactions with a 99% efficiency for the collisions generated by the LHC at a ...

Discontinuities In The Electromagnetic Fields Of Vortex Beams In The Complex Source-Sink Model, 2017 University of Nebraska - Lincoln

Discontinuities In The Electromagnetic Fields Of Vortex Beams In The Complex Source-Sink Model, Andrew Vikartofsky, Liang-Wen Pi, Anthony F. Starace

Anthony F. Starace Publications

An analytical discontinuity is reported in what was thought to be the discontinuity-free exact nonparaxial vortex beam phasor obtained within the complex source-sink model. This discontinuity appears for all odd values of the orbital angular momentum mode. Such discontinuities in the phasor lead to nonphysical discontinuities in the real electromagnetic field components. We identify the source of the discontinuities, and provide graphical evidence of the discontinuous real electric fields for the first and third orbital angular momentum modes. A simple means of avoiding these discontinuities is presented.

Determination Of The Zinc Concentration In Human Fingernails By Laser-Induced Breakdown Spectroscopy, 2017 University of Windsor

Determination Of The Zinc Concentration In Human Fingernails By Laser-Induced Breakdown Spectroscopy, Steven J. Rehse, Vlora A. Riberdy, Christopher J. Frederickson

Physics Publications

The absolute concentration of zinc in human fingernail clippings tested ex vivo was determined by 1064 nm laser-induced breakdown spectroscopy and confirmed by speciated isotope dilution mass spectrometry. A nail testing protocol that sampled across the nail (perpendicular to the direction of growth) was developed and validated by scanning electron microscopy energy dispersive x-ray spectroscopy. Using this protocol, a partial least squares regression model predicted the zinc concentration in five subjects’ fingernails to within 7 ppm on average. The variation of the zinc concentration with depth into the nail as determined by laser-induced breakdown spectroscopy was studied and found to ...

Enhancing High-Order-Harmonic Generation By Time Delays Between Two-Color, Few-Cycle Pulses, 2017 University of Nebraska - Lincoln

Enhancing High-Order-Harmonic Generation By Time Delays Between Two-Color, Few-Cycle Pulses, Dian Peng, Liang-Wen Pi, M. V. Frolov, Anthony F. Starace

Anthony F. Starace Publications

Use of time delays in high-order-harmonic generation (HHG) driven by intense two-color, few-cycle pulses is investigated in order to determine means of optimizing HHG intensities and plateau cutoff energies. Based upon numerical solutions of the time-dependent Schrõdinger equation for the H atom as well as analytical analyses, we show that introducing a time delay between the two-color, few-cycle pulses can result in an enhancement of the intensity of the HHG spectrum by an order of magnitude (or more) at the cost of a reduction in the HHG plateau cutoff energy. Results for both positive and negative time delays as well ...

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, 2017 Embry-Riddle Aeronautical University - Daytona Beach

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales

M. Anthony Reynolds

The quasilinear fluctuation integral is calculated for a two-dimensional, unmagnetized plasma ~composed of charged rods!, and is expressed in terms of Fokker–Planck coefficients. It is found that in two dimensions, the enhanced fluctuations generated by fast electrons lead to anomalously large transport coefficients. In particular, the effect of a small population of fast electrons is only weakly dependent on their density. In three dimensions, the effect of fast electrons is masked by the dominant approximation, but higher-order terms describe processes similar to those in two dimensions, and these terms can become significant for weakly stable plasmas. The differences between ...

Ion Bernstein Waves Driven By Two Transverse Flow Layers, 2017 Embry-Riddle Aeroautical University - Daytona Beach

Ion Bernstein Waves Driven By Two Transverse Flow Layers, Mark Anthony Reynolds, G. Ganguli

M. Anthony Reynolds

The interaction between two narrow layers of E3B flow is investigated, along with their stability properties. The mode frequencies, growth rates, and eigenfunctions are calculated. It is found that the instability due to a single layer is robust to the inclusion of a second layer. Specifically, when the separation between the layers is on the order of the ion-cyclotron radius, there is strong coupling between the two layers and the second layer is destabilizing. In addition, when the flow velocities are in opposite directions a wide variety of modes is possible, including near-zero-frequency modes, resulting in broadband structure in both ...

High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, 2017 Embry-Riddle Aeronautical University - Daytona Beach

High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, Mark Anthony Reynolds

M. Anthony Reynolds

The high-frequency electromagnetic field generated by a density-modulated, helical electron beam propagating in a magnetized plasma is calculated. The magnetic fluctuations are found to exhibit spatially localized ~evanescent! resonances at harmonics of the electron-cyclotron frequency, whose width is determined by the pitch angle of the beam, and whose existence is a consequence of the helical geometry. In addition, electrostatic modes are radiated near the hybrid frequencies, and electromagnetic modes are radiated above the upper-hybrid frequency. The predicted frequency spectrum and mode structure in configuration space are in good agreement with experimental observations of discrete emission lines at the electron-cyclotron harmonics.

2017 Embry-Riddle Aeronautical University

Cross-Scale Energy Transport And Kinetic Wave Properties Associated With Kelvin-Helmholtz Instability, Thomas W. Moore

Dissertations and Theses

In the Earth’s magnetosphere, the magnetotail plasma sheet ions are much hotter than in the shocked solar wind. On the dawn-sector, the cold-component ions are more abundant and hotter by 30-40 percent when compared to the dusk sector. Recent statistical studies of the flank magnetopause and magnetosheath have shown that the level of temperature asymmetry of the magnetosheath is unable to account for this (Dimmock et al., 2015), so additional physical mechanisms must be at play, either at the magnetopause or plasma sheet, that contribute to this asymmetry. This thesis focuses on ion heating across the magnetopause boundary separating ...

Electrostatic Mechanics Of Dust Lofting And Transport On Airless Planetary Bodies, Joseph Schwan

As airless planetary bodies are directly exposed to solar ultraviolet radiation and plasma, an environment that fosters dust charging within planetary regolith will result, producing dust mobilization and transport. A multitude of unsolved in-situ planetary observations linked to electrostatic processes exist, ranging from dust ponds on the asteroid Eros, to intermittently appearing radial spokes in Saturn’s rings, and even to the lunar horizon glow. Available charging models could not adequately explain any of these phenomena. Through careful experimentation a new “Patched Charge Model” has been developed at the NASA/SSERVI’s Institute for Modeling Plasma, Atmospheres and Cosmic Dust ...

Laboratory Simulation Of Solar Wind Interaction With A Magnetic Dipole Field On Lunar Surface, Jia Han

We perform laboratory experiments on the Colorado Solar Wind Experiment (CSWE) device to study the dynamics of the solar wind interaction with lunar magnetic anomalies. A large cross- section plasma ow with ion energies between 100 and 800 eV is incident on an insulating surface embedded in a magnetic dipole field. Plasma is created by a Kaufman ion source. The beam profile has been characterized using a Langmuir probe and an ion Energy Analyzer. The dipole field is created with a permanent magnet behind the surface. 2D potential profiles are measured above the surface using an emissive Langmuir probe. With ...

2017 University of Kentucky

Orbital Stability Results For Soliton Solutions To Nonlinear Schrödinger Equations With External Potentials, Joseph B. Lindgren

Theses and Dissertations--Mathematics

For certain nonlinear Schroedinger equations there exist solutions which are called solitary waves. Addition of a potential $V$ changes the dynamics, but for small enough $||V||_{L^\infty}$ we can still obtain stability (and approximately Newtonian motion of the solitary wave's center of mass) for soliton-like solutions up to a finite time that depends on the size and scale of the potential $V$. Our method is an adaptation of the well-known Lyapunov method.

For the sake of completeness, we also prove long-time stability of traveling solitons in the case $V=0$.

2017 University of Vermont

Investigation Of Pyrolysis Gas Chemistry In An Inductively Coupled Plasma Facility, Corey Tillson

The pyrolysis mechanics of Phenolic Impregnated Carbon Ablators (PICA) makes it a valued material for use in thermal protection systems for spacecraft atmospheric re-entry. The present study of the interaction of pyrolysis gases and char with plasma gases in the boundary layer over PICA and its substrate, FiberForm, extends previous work on this topic that has been done in the UVM 30 kW Inductively Coupled Plasma (ICP) Torch Facility. Exposure of these material samples separately to argon, nitrogen, oxygen, air, and carbon dioxide plasmas, and combinations of said test gases provides insight into the evolution of the pyrolysis gases as ...

2016 University of New Mexico

Experimental Investigation Of Plasma Dynamics In Jets And Bubbles Using A Compact Coaxial Plasma Gun In A Background Magnetized Plasma, Yue Zhang

Electrical and Computer Engineering ETDs

Numerous solar and astrophysical observations of jet- and bubble-like plasma structures exhibit morphological similarities, suggesting that there may be common plasma physics at work in the formation and evolution processes of these structures at different system scales. The ideal magnetohydrodynamics (MHD) provide the necessary theoretical basis for employing laboratory experiments to investigate key physical processes in nonlinear astrophysical and solar systems, especially when magnetic fields are present.

A coaxial magnetized plasma gun has been designed, installed, and operated in the HelCat linear device at the University of New Mexico. In Region I, a current-driven plasma jet is formed. The plasma ...

Accordion Effect Revisited: Generation Of Comb-Like Electron Beams In Plasma Channels, 2016 CEA, DAM DIF

Accordion Effect Revisited: Generation Of Comb-Like Electron Beams In Plasma Channels, Serge Y. Kalmykov, X. Davoine, Remi Lehe, Agustin F. Lifschitz, Bradley A. Shadwick

Serge Youri Kalmykov

Propagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate comb-like electron beams – sequences of synchronized, low phase-space volume bunches with controllable energy difference. The tail of the pulse, confined in the accelerator cavity (electron density “bubble”), transversely flaps, as the pulse head steadily self-guides. The resulting oscillations of the cavity size cause periodic injection of electrons from ambient plasma, creating an energy comb with the number of components, their energy, and energy separation dependent on the channel radius and pulse length. Accumulation of noise (continuously injected charge) can be prevented using a negatively ...

2016 CEA, DAM DIF

Electron Acceleration And Generation Of High-Brilliance X-Ray Radiation In Kilojoule, Subpicosecond Laser-Plasma Interactions, Serge Y. Kalmykov, X. Davoine

Serge Youri Kalmykov

Petawatt, picosecond laser pulses offer rich opportunities in generating synchrotron x-rays. This paper concentrates on the regimes accessible with the PETAL laser, which is a part of the Laser Megajoule (LMJ) facility. We explore two physically distinct scenarios through Particle-in-Cell simulations. The first one realizes in a dense plasma, such that the period of electron Langmuir oscillations is much shorter than the pulse duration. Hallmarks of this regime are longitudinal breakup (“self-modulation”) of the picosecond-scale laser pulse and excitation of a rapidly evolving broken plasma wake. It is found that electron beams with a charge of several tens of nCcan ...

Exploring Mathematical Strategies For Finding Hidden Features In Multi-Dimensional Big Datasets, 2016 University of Houston

Exploring Mathematical Strategies For Finding Hidden Features In Multi-Dimensional Big Datasets, Tri Duong, Fang Ren, Apurva Mehta

STAR (STEM Teacher and Researcher) Presentations

With advances in technology in brighter sources and larger and faster detectors, the amount of data generated at national user facilities such as SLAC is increasing exponentially. Humans have a superb ability to recognize patterns in complex and noisy data and therefore, data is still curated and analyzed by humans. However, a human brain is unable to keep up with the accelerated pace of data generation, and as a consequence, the rate of new discoveries hasn't kept pace with the rate of data creation. Therefore, new procedures to quickly assess and analyze the data are needed. Machine learning approaches ...

Imaging Population Transfer In Atoms With Ultrafast Electron Pulses, 2016 Purdue University

Imaging Population Transfer In Atoms With Ultrafast Electron Pulses, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

We propose the use of ultrafast electron diffraction (UED) to image a controllable, laser-driven coherent electron population transfer in lithium atoms with currently available femtosecond electron pulses. Our simulations demonstrate the ability of ultrafast electrons to image such an electronic population transfer, thus validating UED as a direct means of investigating electron dynamics. Provided the incident electron pulses have sufficient temporal resolution, the diffraction images are shown to resolve also the relative phases of the target electronic wave functions.

Optimization And Coding Of A Lcls Control Program, 2016 California Polytechnic State University, San Luis Obispo

Optimization And Coding Of A Lcls Control Program, Tanner M. Worden

STAR (STEM Teacher and Researcher) Presentations

SLAS’s, Linac Coherent Light Source (LCLS) also known as X-ray free-electron laser (XFEL) is the first X-ray laser of its kind. It gave Scientist from around the world the unique ability to observe the world at a subatomic level. Allowing for major advancements in the field of biological chemistry, drug science, material science and many more. Since the LCLS is a fairly unique scientific instrument, the demand for its use by the scientific community has always been high since it turned on back in 2009. This means that any and all time that the laser is not being used ...

High-Flux Femtosecond X-Ray Emission From Controlled Generation Of Annular Electron Beams In A Laser Wakefield Accelerator, 2016 Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109

High-Flux Femtosecond X-Ray Emission From Controlled Generation Of Annular Electron Beams In A Laser Wakefield Accelerator, T. Z. Zhao, K. Behm, C. F. Dong, X. Davoine, Serge Y. Kalmykov, V. Petrov, Vladimir Chvykov, P. Cummings, B. Hou, Anatoly Maksimchuk, J. A. Nees, Victor Yanovsky, A. G. R. Thomas, Karl Krushelnick

Serge Youri Kalmykov

Annular quasimonoenergetic electron beams with a mean energy in the range 200–400 MeV and charge on the order of several picocoulombs were generated in a laser wakefield accelerator and subsequently accelerated using a plasma afterburner in a two-stage gas cell. Generation of these beams is associated with injection occurring on the density down ramp between the stages. This well-localized injection produces a bunch of electrons performing coherent betatron oscillations in the wakefield, resulting in a significant increase in the x-ray yield. Annular electron distributions are detected in 40% of shots under optimal conditions. Simultaneous control of the pulse duration ...

Simulation Of Relativistic Electrons Through A Magnetic Chicane, 2016 University of Nebraska-Lincoln

Simulation Of Relativistic Electrons Through A Magnetic Chicane, Matthias Fuchs, John Chrostek, Nathan W. Ray, Jordan O'Neal

UCARE Research Products

Poster describing the path length differences for two relativistic electrons going through a series of four dipoles. This preliminary work will lead to full simulation of electron beam being compressed for use in an X-Ray Free Electron Laser in conjunction with magnetic quadruple lenses to create a small electron beam.