Plasma and Beam Physics Commons^™

Arrayed Waveguide Lens For Beam Steering, Mostafa Honari-Latifpour, Ali Binaie, Mohammad Amin Eftekhar, Nicholas Madamopoulos, Mohammad-Ali Miri

Publications and Research

Integrated planar lenses are critical components for analog optical information processing that enable a wide range of applications including beam steering. Conventional planar lenses require gradient index control which makes their on-chip realization challenging. Here, we introduce a new approach for beam steering by designing an array of coupled waveguides with segmented tails that allow for simultaneously achieving planar lensing and off-chip radiation. The proposed arrayed waveguide lens is built on engineering the evanescent coupling between adjacent channels to realize a photonic lattice with an equi-distant ladder of propagation constants that emulates the continuous parabolic index profile. Through coupled-mode analysis …

Ultrashort Pulse Laser Filamentation Electrical And Optical Diagnostic Comparison, James E. Wymer

Optical Science and Engineering ETDs

Results presented here examine the effect of changing gas pressure on the radio frequency (RF) emissions of an ultrashort pulse laser filament plasma and how those emissions vary longitudinally in the laser focal region. We use a WR284 rectangular waveguide with a 1.5 cm hole that allows the beam through. A 3.2 GHz microwave signal is emitted in the waveguide, and signals are received through a waveguide-to-coax antenna connected to an HP8470B Schottky diode. By enabling and disabling the 3.2 GHz signal, we measure both the self-emitted RF from a USPL filament and subsequently the degree of attenuation a filament …

Design And Commissioning Of An E-Beam Irradiation Beamline At The Upgraded Injector Test Facility At Jefferson Lab, Xi Li, Helmut Baumgart, Charles Bott, Gianluigi Ciovati, Shaun Gregory, Fay Hannon, Mike Mccaughan, Robert Pearce, Matthew Poelker, Hannes Vennekate, Shaoheng Wang

Electrical & Computer Engineering Faculty Publications

The Upgraded Injector Test Facility (UITF) at Jefferson Lab is a continuous-wave superconducting linear accelerator capable of providing an electron beam with energy up to 10 MeV. A beamline for electron-beam irradiation has been designed, installed and successfully commissioned at this facility, aimed at the degradation study of 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS) in wastewater treatment. A solenoid with a peak axial magnetic field of up to 0.28 T and a set of raster coils were used to obtain a Gaussian beam profile with a transverse standard deviation of ∼15.0 mm at the target location. Monte-Carlo simulations using …

Synthesis Of Polynitrogen With Radio Frequency Plasma, Haizheng Zhuang

Dissertations

Cubic gauche polynitrogen (cgPN) has been very attractive due to its high energy density that is 2.5 times higher than that of TNT. In the literature, cgPN has been investigated theoretically in detail, but few experimental works have been reported. In 2004, cgPN was first synthesized from nitrogen gas under extremely high temperature and high pressure (HTHP) conditions and the trace amount of cgPN in the high-pressure vessel decomposed once the pressure was released. Until recently, our group was the first to synthesize cgPN from NaN₃ precursor under ambient conditions with radio frequency (RF) plasma. In this study, the …

Artificial Intelligence, Controls, And Sensor Fusion For Optimization And Modeling Of Space Missions And Particle Accelerators, Reza Pirayeshshirazinezhad

Mechanical Engineering ETDs

This PhD dissertation is devoted to developing artificial intelligence (AI) applications for space missions and particle accelerators considering constraints on the computational resources. The space mission studied in this research, the Virtual Telescope for X-ray Observations (VTXO), is the mission exploiting 2 6U-CubeSats operating in a precision formation. The goal of the VTXO project is to develop a space-based, X-ray imaging telescope with high angular resolution precision. VTXO space mission is designed and the mission is optimized to increase the performance of the mission. Trajectory optimization with AI, hybrid control, control algorithms, and high performance computing are all used to …

Synthesis Of Cuo/Zno And Mgo/Zno Core/Shell Nanoparticles With Plasma Jets And Study Of Their Structural And Optical Properties, Raghad S. Mohammed, Kadhim A. Aadim, Khalid A. Ahmed

Karbala International Journal of Modern Science

This paper reports the synthesis of CuO/ZnO and MgO/ZnO core/shell nanoparticles using atmospheric plasma jets. The characterization of the synthesized CuO/ZnO and MgO/ZnO core/shell nanoparticles were confirmed by a series of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and UV–Vis spectroscopy. The XRD analysis confirmed no other peaks related to the secondary phases for CuO, MgO, or ZnO, indicating the purity of these nanoparticles. Additionally, EDX analysis confirmed the formation of high purity CuO/ZnO and MgO/ZnO core/shell nanoparticles. The surface morphology, which represented the high agglomeration rate, was investigated using …

Structural And Spectroscopic Analysis For Silver Bulk And Nanoparticles, Hajir M. Fadhil, Khaleel I. Hassoon, Hyder A. Salih

Karbala International Journal of Modern Science

In this research work, a pulsed Nd-YْAG laser having a wavelength of 1064 nm and energy (400-700 mJ (has been utilized as a source in an induced breakdown spectroscopy (LIBS) experiment to determine the density of electron and the tem-perature of Ag-plasma. Two forms of silver (as a bulk and as a compressed nano powder) have been used as targets in the LIBSs setup. The aim of the present work is to study the impact of target properties and laser energy on the plasma fea-tures formed by the interaction between a pulsed laser and these two forms of silver. The …

Particle-In-Cell Simulations Of Ion Dynamics In A Pinched-Beam Diode, Jesse C. Foster, John W. Mcclory, S. B. B. Swanekamp, D. D. Hinshelwood, A. S. Richardson, Paul E. Adamson, J. W. Schumer, R. W. James, P. F. Ottinger, D. Mosher

Faculty Publications

article-in-cell simulations of a 1.6 MV, 800 kA, and 50 ns pinched-beam diode have been completed with emphasis placed on the quality of the ion beams produced. Simulations show the formation of multiple regions in the electron beam flow characterized by locally high charge and current density (“hot spots”). As ions flow through the electron-space-charge cloud, these hot spots electrostatically attract ions to produce a non-uniform ion current distribution. The length of the cavity extending beyond the anode-to-cathode gap (i.e., behind the cathode tip) influences both the number and amplitude of hot spots. A longer cavity length increases the number …

Electrothermal Plenum Thruster Simulations Varying Input Pressure And Voltage, Naomi Nicole Ingram

Open Access Theses & Dissertations

A radiofrequency electrothermal thruster is designed and simulated to create a low ionization energy plasma from a neutral propellant using a radio-frequency power. With an asymmetrical surface area ratio between the grounded and powered electrode, ion-neutral charge exchange collisions occurring within the propellant result in propellant heating. The Electrothermal Plenum Thruster conducts this propellant heating in an annular plenum chamber in attempt to maximize propellant heating. A software called CFD-ACE+ is utilized to demonstrate the effects of an enhanced sheath from the asymmetrical power coupling arrangement. Two sets of simulations are run to understand how input variables affect the plasma …

Foundations Of Plasmas For Medical Applications, T. Von Woedtke, Mounir Laroussi, M. Gherardi

Electrical & Computer Engineering Faculty Publications

Plasma medicine refers to the application of nonequilibrium plasmas at approximately body temperature, for therapeutic purposes. Nonequilibrium plasmas are weakly ionized gases which contain charged and neutral species and electric fields, and emit radiation, particularly in the visible and ultraviolet range. Medically-relevant cold atmospheric pressure plasma (CAP) sources and devices are usually dielectric barrier discharges and nonequilibrium atmospheric pressure plasma jets. Plasma diagnostic methods and modelling approaches are used to characterize the densities and fluxes of active plasma species and their interaction with surrounding matter. In addition to the direct application of plasma onto living tissue, the treatment of liquids …

Lattice Optics Optimization For Recirculatory Energy Recovery Linacs With Multi-Objective Optimization, Isurumali Neththikumara, Todd Satogata, Alex Bogacz, Ryan Bodenstein, Arthur Vandenhoeke

College of Sciences Posters

Beamline optics design for recirculatory linear accelerators requires special attention to suppress beam instabilities arising due to collective effects. The impact of these collective effects becomes more pronounced with the addition of energy recovery (ER) capability. Jefferson Lab’s multi-pass, multi-GeV ER proposal for the CEBAF accelerator, ER@CEBAF, is a 10- pass ER demonstration with low beam current. Tighter control of the beam parameters at lower energies is necessary to avoid beam break-up (BBU) instabilities, even with a small beam current. Optics optimizations require balancing both beta excursions at high-energy passes and overfocusing at low-energy passes. Here, we discuss an optics …

Whistler Waves: Modeling And Observations, Daniel Williams

Doctoral Dissertations and Master's Theses

The thesis presents the results of all the research from the published and in publication process research in the Journal of Geophysical Research [1]. This research focuses on whistler wave ducting events in the equatorial magnetosphere. High-density ducts are the main focus of whistler study in both studies as they are commonly observed by the Van Allen Probe satellites. A three-step procedure based on the analysis of the whistler wave dispersion relation and numerical simulations of the electron magnetohydrodynamics model. We use this model to identify the parallel and perpendicular wave numbers of the “most trapped” wave in an attempt …

Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice

Doctoral Dissertations and Master's Theses

The detailed mechanisms coupling the solar wind to Earth's magnetosphere are not yet fully understood. Solar wind plasma is heated non-adiabatically as it penetrates the magnetosphere, and this process must span scale sizes. Reconnection alone is not able to account for the observed heating; other mechanisms must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various ion scale wave modes, mode conversion, and turbulence associated …

Pseudo-Modal Expansions For Generating Random Electromagnetic Beams, Milo W. Hyde Iv, Olga Korotkova

Faculty Publications

Excerpt: We derive two pseudo-modal expansions that provide insight into the structure of stationary electromagnetic sources and can be used for their physical realization and in computer simulations. Both expansions are derived from the vectorial version of Bochner’s theorem of functional analysis.

Microwave Enhanced Electron Energy Distribution Functions, John Samuel Mckee

Graduate Theses, Dissertations, and Problem Reports (ETD)

The use of two (or more) radio frequency (RF) sources at different frequencies is a common technique in the plasma processing industry to control ion energy characteristics separately from plasma generation. A similar approach is presented here with the focus on modifying the electron population in argon and helium plasmas. The plasma is generated by a helicon source at a frequency f0 = 13.56 MHz. Microwaves of frequency f1 = 2.45 GHz are then injected into the helicon source chamber perpendicular to the background magnetic field. The microwaves damp on the electrons via R-mode (anti-parallel to the background magnetic field …

Scaling Theory Of 3d Magnetic Reconnection X-Line Spreading, Milton Arencibia

Graduate Theses, Dissertations, and Problem Reports (ETD)

Magnetic reconnection is fundamental process in plasmas that converts magnetic energy into kinetic and thermal energy via a change in magnetic topology. Magnetic reconnection is known to mediate eruptive solar flares, geomagnetic substorms that create the Northern lights, heating and particle acceleration in controlled fusion devices, and is thought to be an important process in numerous settings in high-energy astrophysics. Classical models of reconnection are two-dimensional (2D), but naturally occurring reconnection is three-dimensional (3D), and a manifestation of the 3D nature is that the x-line where the magnetic field topology changes has a finite extent in the direction normal to …

Ion Velocity Distribution Functions In Cutting-Edge Plasmas, Mitchell Cameron Paul

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cutting-edge plasma experiments continue to push the frontiers of plasma science. Two such groups of experiments, helicon sources and laboratory magnetic reconnection, are the focus of this thesis. The relatively high plasma density achieved for modest input powers makes helicon source plasmas ideal testbeds for fusion-relevant phenomena without the complexities associated with fusion devices. Examples include plasma-material interaction (PMI) studies, divertor region studies, and boundary physics studies. As advancements in helicon source design and technology make operation at higher power for longer times possible, understanding of the plasma dynamics, particularly ion dynamics, is vital.

Laboratory experiments are essential to advancing …

Numerical Investigations Of 2-D Magnetic Nozzles On Pulsed Plasma Plumes, Joshua Daniel Burch

Masters Theses

"This research presents studies of a novel type of magnetic nozzle that allows for three-dimensional (3-D) steering of a plasma plume. Numerical simulations were performed using Tech-X's USim® software to quantify the nozzle's capabilities. A2-D planar magnetic nozzle was applied to plumes of a nominal pulsed inductive plasma (PIP) source with discharge parameters similar to those of Missouri S&T's Missouri Plasmoid Experiment (MPX). Argon and xenon plumes were considered. Simulations were verified and validated through a mesh convergence study as well as comparison with available experimental data. Periodicity was achieved over the simulation run time and phase angle samples were …

A Laser Frequency Transverse Modulation Might Compensate For The Spectral Broadening Due To Large Electron Energy Spread In Thomson Sources, Vittoria Petrillo, Illya Drebot, Geoffrey Krafft, Cesare Maroli, Andrea R. Rossi, Marcello Rossetti Conti, Marcel Ruijter, Balša Terzić

Physics Faculty Publications

Compact laser plasma accelerators generate high-energy electron beams with increasing quality. When used in inverse Compton backscattering, however, the relatively large electron energy spread jeopardizes potential applications requiring small bandwidths. We present here a novel interaction scheme that allows us to compensate for the negative effects of the electron energy spread on the spectrum, by introducing a transverse spatial frequency modulation in the laser pulse. Such a laser chirp, together with a properly dispersed electron beam, can substantially reduce the broadening of the Compton bandwidth due to the electron energy spread. We show theoretical analysis and numerical simulations for hard …

Direct Current Magnetic Hall Probe Technique For Measurement Of Field Penetration In Thin Film Superconductors For Superconducting Radio Frequency Resonators, Iresha Harshani Senevirathne, Alex Gurevich, Jean Delayen

Physics Faculty Publications

Superconducting Radio Frequency (SRF) cavities used in particle accelerators are typically formed from or coated with superconducting materials. Currently, high purity niobium is the material of choice for SRF cavities that have been optimized to operate near their theoretical field limits. This brings about the need for significant R & D efforts to develop next generation superconducting materials that could outperform Nb and keep up with the demands of new accelerator facilities. To achieve high quality factors and accelerating gradients, the cavity material should be able to remain in the superconducting Meissner state under a high RF magnetic field without …