Engineering Commons^™

Miniature, Submersible Electromagnetic Pumps Of Molten Lead And Sodium For Gen-Iv Nuclear Reactors Development, Ragai M. Altamimi

Nuclear Engineering ETDs

Heavy metals and alkali Liquid Metals are suitable coolants for Generation IV terrestrial nuclear reactors for operating at elevated temperatures for achieving plant thermal efficiency more than 40% and the thermochemical generation of hydrogen fuel. In addition, the low vapor pressure of these liquids eliminates the need for a pressure vessel and instead operates slightly below ambient pressure. A primary issue with the uses of these coolants is their compatibility with nuclear fuel, cladding and core structure materials at elevated temperatures more than 500oC. Therefore, in pile and out-of-pile test loops have been constructed or being considered for quantifying the …

Adaptive Gps Antenna Array Beam Nulling Effectiveness Under Varying Antenna Element Positioning, Aadesh Neel

Electrical and Computer Engineering ETDs

Global Positioning System (GPS) is an essential part of modern life but is susceptible to same frequency jamming. GPS jamming can add excessive noise to a received low power signal and have the capability to change or completely distort information being sent through the GPS signal. Adaptive antenna arrays have long since been a solution to mitigating GPS jamming via beamnulling algorithms. However, there is little research on the effectiveness of these beamnulling algorithms under varying element positioning. In this work, an adaptive antenna array, consisting of Right-Hand Circularly Polarized (RHCP) nearly square GPS antenna elements, was constructed and tested …

Theory, Simulation, And Experiments On A Magnetically Insulated Transmission Line Terminated By A Bremsstrahlung Diode, Troy Clay Powell

Electrical and Computer Engineering ETDs

Foundational concepts necessary for power flow analysis of a self-magnetically insulated transmission line (MITL) are introduced in theoretical form and several developments to the theory are described. These include cold-cathode electron emission physics, self-magnetic insulation physics, self-limited MITL current, and relativistic secondary ion production from anode surfaces. Modeling these physics is performed using EMPIRE, an electromagnetic particle-in-cell code.

Self-limited MITL current theory described numerically by Pointon is developed here in analytic form and is then used to drive simulations to compare to experiments that were performed in EMPIRE. Carefully calibrated current sensors from HERMES-III experiments show good agreement with EMPIRE …

Evaluation Of The Dynamic Vision Sensor’S Photoreceptor Circuit For Infrared Event-Based Sensing, Zinah M. Alsaad

Electrical and Computer Engineering ETDs

For space surveillance applications, neuromorphic imaging is being studied as it may perform sensing and tracking tasks with less power and downstream datalink demand. The read-out of the event-based camera is made to only be sensitive to changes in the signals it receives from the photodetector, which results in a datastream of events indicating where and when changes in illumination occur. This is in contrast to the conventional framing camera, which produces images by essentially counting the electrons produced by light incident on each pixel’s photodetector. These cameras are commercially available with siliconbased detectors for applications involving visible wavelengths. However, …

Improved Experimental Validation Of An Electromagnetic Subcell Model For Narrow Slots With Depth, Michael Anthony Illescas

Electrical and Computer Engineering ETDs

The coupling of electromagnetic (EM) energy into a system can disrupt operation of essential electronics present within it. Metal enclosures are used to shield these systems from potentially harmful electromagnetic interference (EMI). Seams and gaps in such metal enclosures are minimized but unavoidable for reasons such as maintenance and repair. These seams and gaps create an entry point for EM energy to couple into the system. Entry points are often modeled by EM analysts as narrow slots defined by their length, width, and depth. The depth of these slots can become significant compared to the wavelength, introducing resonances associated with …

A Study On Electromagnetic Topology Optimization Using Binary Particle Swarm Algorithm, Mohammad Sazzad Hossain

Electrical and Computer Engineering ETDs

Topology optimization is a state-of-the-art tool for detecting the best material layout in a physical space to obtain certain goals. Initially developed as a structural engineering tool, it has been recently used in electromagnetics and has shown immense potential. The aim of this work is to build a framework for applying the topology optimization method in electromagnetics using a modified binary particle swarm optimization (BPSO) algorithm. In this thesis, a very classic problem of coax to waveguide transition has been considered, and a novel solution has been given using topology optimization. The steps to implementing topology optimization using BPSO have …

Intracavity Phase Interferometry Based Fiber Sensors, Luke Jameson Horstman

Optical Science and Engineering ETDs

Intracavity Phase Interferometry (IPI) is a detection technique that exploits the inherent sensitivity of a laser's frequency to the parameters of its cavity. Intracavity interferometry is orders of magnitude more sensitive than its extracavity alternatives. This dissertation improves on previous free-space proof-of-concept designs. By implementing the technique in fiber optics, using optical parametric oscillation, and investigating non-Hermitian quantum mechanics and dispersion tailoring enhancement techniques, IPI has become more applicable and sensitive. Ring and linear IPI configurations were realized in this work, both operating as bidirectional fiber optical parametric oscillators. The benefit of using externally pumped synchronous optical parametric oscillation is …

Self-Breakdown Study Of Spherical Electrodes In Air Spanning Pressures From Atmosphere To 2000 Psia, And Stress Times From Seconds To Nanoseconds, Joseph G. Felix

Electrical and Computer Engineering ETDs

In this research, a self-breakdown switch with 12.7 mm diameter spherical electrodes and a 380-micron gap was assembled and the effect of pressure and stress time on breakdown voltage and closure time were measured. Specifically, the pressure was varied from atmosphere to 2000 psia and the stress time was varied from seconds to nanoseconds. Few studies have investigated equivalent ranges of pressure and charge times on sub millimeter gap switches with electric field intensities reaching 2 MV/cm. The correlation of the parameters and switch behavior are explored in this study. In addition, the effects of humidity and electrode surface deformities …

A Reconfigurable Stretchable Liquid Metal Antenna, Phase Shifter, And Array For Wideband Applications, David M. Hensley

Electrical and Computer Engineering ETDs

While liquid metals, such as mercury, have been used in electronics for quite some time, the non-toxic gallium based liquid metals have caused an increase in research for liquid metal applications. Some of the potential applications that have been previously presented range from reconfigurable antennas, strain and pressure sensors, and speakers and microphones to name a few. The focus of this work is to provide further research into the use of gallium based liquid metals as a reconfigurable antenna, a phase shifter, and an array. This is done by designing, constructing, and characterizing each of these reconfigurable liquid metal (LM) …

Experimental Validation Of A 3d-Printed Millimeter Wave/Thz Power Combiner, Jacob C. Giese

Electrical and Computer Engineering ETDs

The terahertz band (THz) in the electromagnetic spectrum is an untapped resource that possesses unique features for nondestructive methods of material imaging and detection. However, little advancements have been made in regard to a practical long range portable THz device. The solution proposed is an oversized cylindrical waveguide termed Power Combiner, designed to combine 12 azimuthally aligned rectangular waveguides to produce power levels suitable for threat detection at secure distances. This paper explores the physical parameters of the power combiner and the power distribution network and creates the 12 signals that allow for modification at the input of the power …

On The Dynamic Generation Of Megagauss-Level Magnetic Fields On 100-Ns Timescales To Stabilize And Magnetize Pulsed-Power-Driven Liner Implosions, Gabriel A. Shipley

Electrical and Computer Engineering ETDs

This dissertation presents analysis of experiments and simulations executed to develop the auto-magnetizing liner concept (AutoMag) for use as an alternative premagnetization mechanism for MagLIF. Tests of each stage of AutoMag (magnetization, dielectric breakdown, and implosion) were executed on the Mykonos accelerator and the Z accelerator. Experiments demonstrate strong peak axial magnetic field production (20 – 150 T), dielectric breakdown initiation that depends on global induced electric field across the target, and a level of cylindrical implosion uniformity high enough to be useful for prospective fusion-fuel-filled (auto-magnetized MagLIF) experiments.

This dissertation also presents detailed simulations of the Solid Liner Dynamic …

Computational_Electromagnetic Modeling (Cem) Of Foliage Penetration (Fopen), Monica R. Jaramillo

Electrical and Computer Engineering ETDs

Foliage penetration (FOPEN) radar at lower frequencies (UHF, VHF) is a well-studied area with a wide set of contributions. However, there is growing interest in using higher Ku-band frequencies (12-18 GHz frequency range) for FOPEN. In particular, the reduced wavelength sizes (centimeters range) provide some key saliencies for developing more optimized foliage detection solutions. The disadvantage is that exploiting Ku-band for FOPEN is complicated because higher frequencies have much more pronounced scattering effects due to their smaller wavelengths. Despite these challenges, certain foliage characteristics and signal parameters can help improve electromagnetic (EM) wave penetration in the Ku-band such as foliage …

Source Localization With Machine Learning, Arjun Gupta

Electrical and Computer Engineering ETDs

Source localization with sensor arrays have found applications across domains beginning with radar and sonar, astronomy, acoustics, bio-medical devices and more recently in autonomous cars and adaptive communication systems. The knowledge of the spatial spectrum not only provide information about the source and interference but also assists in increasing signal integrity and avoid interference. This provides an added degree of freedom in the form of spatial diversity. This research investigates spatial spectrum estimation of waveforms from the signals sampled by arbitrarily distributed sensors. Conventional high resolution algorithms such as root-MuSiC fails to perform accurate source localization due to the reliance …

Advanced Parallel Algorithms In Computational Electromagnetics, Shu Wang

Electrical and Computer Engineering ETDs

The rapid development of high performance computing has pushed the computational electromagnetic(CEM) towards high accuracy, high fidelity and extreme computational scales. There is a great need for existing CEM solvers to have enhanced parallelism and scaling capability. The purpose of this dissertation is to investigate advanced parallel algorithms for both frequency and time domain solvers.

In frequency domain, this work first develop the underpinnings of parallel preconditioning technique and high-order transmission condition in the context of multi-solver scheme. The result is a computing resource-aware and implementation wise compact solver. Then this work targeted at developing efficient algorithms for cases where …

Advancing Compact Pulsed Power, Jon C. Pouncey

Electrical and Computer Engineering ETDs

The first two decades of the 21^st century have seen significant interest in expanding the application of pulsed power technology beyond its traditional use in physics and nuclear weapons research. Applications in the field of national defense, which present unique constraints on system size, have provided impetus to increase the exploration of compact pulsed power solutions. Innovations related to energy density, insulation, switching, and power conversion systems have been realized, bringing deployable compact pulsed power systems closer to realization than ever before. However, recent systems integration efforts have shown that work still remains to develop needed tools and technologies …

Inhibiting Surface Flashover In Vacuum With High Gradient Insulators, Cameron Harjes

Electrical and Computer Engineering ETDs

In high voltage systems, insulators may be used to separate conductors and these insulators are typically the limiting factor in the system’s operating voltage. When the voltage between two conductors is too large, the insulators can fail due to surface flashover. As systems become more compact, the threat of failure by insulator flashover increases, making the optimization of insulators a critical task for reliability.

Insulators at a vacuum interface are especially vulnerable to surface flashover. Insulators have been shown to holdoff more voltage in vacuum after being baked to remove imbedded surface gases. Ceramic materials are particularly attractive because, unlike …

Integrated Chirped-Grating Spectrometer-On-A-Chip, Shima Nezhadbadeh

Optical Science and Engineering ETDs

In this dissertation we demonstrate a new structure based on waveguide coupling atop a silicon wafer using a chirped grating to provide the dispersion that leads to a high-resolution, compact, fully integrable and CMOS-compatible spectrometer. Light is both analyzed and detected in a single, completely monolithic component which enables realizing a high-resolution portable spectrometer with an extremely compact footprint. The structure is comprised of a SiO₂/Si₃N₄/SiO₂ waveguide on top of a silicon wafer. Grating regions are fabricated on the top cladding of the waveguide. The input light is incident on a chirped grating …

Algorithmic Multi-Color Cmos Avalanche Photodiodes For Smart-Lighting Applications, Md Mottaleb Hossain

Optical Science and Engineering ETDs

Future smart-lighting systems are expected to deliver adaptively color-tunable and high-quality lighting that is energy efficient while also offering integrated visible-light wireless communication services. To enable these systems at a commercial level, inexpensive and fast sensors with spectral-sensing capability are required. CMOS-compatible silicon avalanche photodiodes (APDs) can be an excellent fit to this problem due to their excellent sensitivity, high speeds and cost effectiveness; however, color sensing is a challenge without resorting to expensive spectral filters, as done in commercially. To address this challenge, we have recently designed and modeled a novel CMOS-compatible dual-junction APD. The device outputs two photocurrents …

Non-Invasive Beam Monitoring With Harmonic Cavities, Brock F. Roberts

Electrical and Computer Engineering ETDs

NON INVASIVE BEAM MONITORING WITH HARMONIC CAVITIES

by

Brock Franklin Roberts

B.S PHYSICS, UNIVERSITY OF CALIFORNIA DAVIS, 1992

DOCTOR OF PHILOSOPHY IN ELECTRICAL ENGINEERING

UNIVERSITY OF NEW MEXICO, 2019

ABSTRACT

A cavity designed to have multiple harmonic TM0N0 modes can be used to accurately measure the longitudinal profile of a bunched charged particle beam passing through its bore, non-invasively, and in real time.

Multi-harmonic TM0N0 cavities were designed, constructed, and beamline tested in a variety of experiments at the Thomas Jefferson National Accelerator Facility (TJNAF or Jlab). Measurements with a sampling oscilloscope provided signals that resemble the profile of electron …

Design And Implementation Of A 72 & 84 Ghz Terrestrial Propagation Experiment; Exploitation Of Nexrad Data To Statistically Estimate Rain Attenuation At 72 Ghz, Nicholas Pawel Tarasenko

Electrical and Computer Engineering ETDs

The wireless communication sector is rapidly approaching network capacities as a direct result of increasing mobile broadband data demands. In response, the Federal Communications Commission allocated 71-76 GHz “V-band” and 81-86 GHz “W-band” for terrestrial and satellite broadcasting services. Movement by the telecommunication industry towards W/V-band operations is encumbered by a lack of validated and verified propagation models, specifically models to predict attenuation due to rain. Additionally, there is insufficient data available at W/V-bands to develop or test propagation models. The first aim of this study was the successful installation and operation of a terrestrial link to collect propagation data …

A Narrow-Wall Complementary-Split-Ring Slotted Waveguide Antenna For High-Power-Microwave Applications, Xuyuan Pan

Electrical and Computer Engineering ETDs

A narrow-band, rugged, complementary-split-ring (CSR) slotted waveguide antenna (SWA) with significant size reduction is presented. The antenna is to be vertically front mounted on a land vehicle, with a horizontally polarized fan-beam radiation pattern. The radiation characteristics of a CSR slot in the narrow-wall of a rectangular waveguide are studied for the first time in this work. Both simulation and experimental results show that the complementary-split-ring slot radiates a linearly polarized wave with a total efficiency and gain close to those of conventional longitudinal slots, while the proposed CSR slots have a maximal outer diameter of 0.23λ₀, much …

Pulse Sharpening Circuit For Explosive Emission Cathode Driver, Nicholas D. Kallas

Electrical and Computer Engineering ETDs

Explosive field emission cathodes (EEC), used for the generation of relativistic electron beams, require short rise-time high-voltage pulses in order to minimize the extraction of off-energy electrons. To this end, a rise-time sharpening circuit has been developed at the Los Alamos National Laboratory (LANL). The circuit consists of a 7 nF water-filled peaking capacitor with an integrated self-breakdown switch designed to operate up to -300 kV. This unit is intended to reduce the rise-time of a 4-stage Type-E PFN Marx Generator that will be used to study operational characteristics of velvet cathodes. Simulations of the peaking circuit show a reduction …

Novel Compact Narrow-Linewidth Mid-Infrared Lasers For Sensing Applications, Behsan Behzadi

Optical Science and Engineering ETDs

The mid-infrared (2-14 μm) spectral region contains the strong absorption lines of many important molecular species, which make this region crucial for several well-know applications such as spectroscopy, chemical and biochemical sensing, security, and industrial monitoring. To fully exploit this region through absorption spectroscopic techniques, compact and low-cost narrow-linewidth (NLW) mid-infrared (MIR) laser sources are of primary importance.

This thesis is focused on three novel compact NLW MIR lasers: demonstration and characterization of a new glass-based spherical microlaser, investigation of the performance of a novel fiber laser, and the design of a monolithic laser on a silicon chip. Starting with …

Split-Ring Resonator Waveguide Structure Characterization By Simulations, Measurements And Linear Time-Invariant Modeling, Mohamed Aziz Hmaidi

Electrical and Computer Engineering ETDs

Interest in Metamaterials has been rising drastically in the recent years as they have been used in several optical and RF applications, from antennas to perfect lenses and pulsed power devices. Nevertheless, the time-behavior of metamaterials remains opaque and poorly understood.

In this research work, characterization of a metamaterial structure in time and frequency-domain was made through simulations and experiments. The structure consists in a series of edge-side coupled Split Ring Resonators (SRRs) in a below cutoff waveguide. A linear time invariant model of distributed elements has been elaborated as well in an attempt to approach the structure’s behavior. The …

Experimental Testing Of A Metamaterial Slow Wave Structure For High-Power Microwave Generation, Kevin Aaron Shipman

Electrical and Computer Engineering ETDs

Experimental Testing of a Metamaterial Slow Wave Structure for High-Power Microwave Generation

by

Kevin Aaron Shipman

B.S., Exercise Science, University of New Mexico, 2008

A.S., Mathematics, San Juan College, 2014

M.S., Electrical Engineering, University of New Mexico, 2018

Abstract

A high-power L-band microwave source has been developed using a metamaterial (MTM) to produce a biperiodic double negative slow wave structure (SWS) for interaction with an electron beam. The beam is generated by a ~700 kV, ~6 kA short pulse (~ 10 ns) electron beam accelerator. The design of the metamaterial SWS (MSWS) consists of a cylindrical waveguide, loaded with alternating …

An Exploration Of The Optical Detection Of Ionizing Radiation Utilizing Modern Optics Technology, Sean D. Fournier, Adam Hecht, Cassiano De Oliveira, Jeffrey B. Martin, Richard K. Harrison, Charles Potter

Nuclear Engineering ETDs

Modern ultraviolet (UV) cameras, when combined with UV-transmitting lenses/filter arrangements, can be used to detect radiation dose in air. Ionizing radiation excites nitrogen molecules in ambient air, the resulting decay includes weak emission of ultraviolet photons. Previous work has proven this phenomenon is detectable using highly-sensitive electronically cooled cameras traditionally used in astronomy for low-background imaging. While the ability to detect the presence of radiation (i.e. qualitative measurement) has been demonstrated at Sandia National Laboratories, there are several challenges in correlating images to known dose-fields (quantitative measurement). These challenges include: a low signal to background ratio, interferences due to electronic …

Antennas For Wv Band Applications, Firas Ayoub

Electrical and Computer Engineering ETDs

This dissertation focuses on designing, fabricating and testing antennas that are suitable for operation within the V/W bands. In particular, this work focuses on the design of slotted rectangular waveguide antenna arrays and cross slotted waveguide fed horn antennas. These structures are known for their high efficiency and high circularly polarized gain that can be implemented in satellite and terrestrial communication links. In addition, such designs can be implemented in radar applications that operate infrequency bands around 72 GHz or 84 GHz bands. Such antenna structures are inexpensive to fabricate since they can simply be machined using high precision conventional …

Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami

Physics & Astronomy ETDs

Nano-scale optoelectronic devices have gained significant attention in recent years. Among these devices are semiconductor nanowires, whose dimeters range from 100 to 200 nm. Semiconductor nanowires can be utilized in many different applications including light-emitting diodes and laser diodes. Higher surface to volume ratio makes nanowire-based structures potential candidates for the next generation of photodetectors, sensors, and solar cells. Core-shell light-emitting diodes based on selective-area growth of gallium nitride (GaN) nanowires provide a wide range of advantages. Among these advantages are access to non-polar m-plane sidewalls, higher active region area compared to conventional planar structures, and reduction of threading …

Scatterometry Of 50 Nm Half Pitch Features, Ruichao Zhu

Optical Science and Engineering ETDs

Metrology technologies are an essential adjunct to Integrated Circuit (I.C.) Semiconductor manufacturing. Scatterometry, an optical metrology, was chosen to measure 50 nm half pitch feature structures. A bread-board scatterometry system has been assembled to provide a non-contact, non-destructive, accurate and flexible measurement. A real-time, on-line scatterometry system has also been demonstrated and proven to provide a high throughput measurement.

Three different types of samples have been measured using the scatterometry setup. The wire-grid polarizer (WGP) sample has been made by Jet and Flash Nanoimprint Lithography with ~100 nm pitch and ~50 nm wide ~200 nm tall Al gratings on fused …

Rain Attenuation Effects On Signal Propagation At W/V-Band Frequencies, Nadine Daoud

Electrical and Computer Engineering ETDs

The current frequency spectrum congestion in space is begging for the exploration and utilization of a new range of frequencies. The W/V-band Terrestrial Link Experiment (WTLE) project run jointly by AFRL, NASA and the University of New Mexico, focuses on using higher frequencies for satellite communications, more precisely, at 72 GHz and 84 GHz.

In this thesis, the rain effect on the propagating signal is studied. First, instantaneous comparisons between the experiment and two different models, the ITU-R and the Siva-Mello, is presented. Second, the WTLE link was analyzed statistically over a period of approximately 10 months, and the ITU-R …