Engineering Commons^™

Cu/Bnx Catalysts For Electrocatalytic Reduction Of Nitrogen And Nitrate Waste, Siming Huo

Dissertations

Ammonia (NH₃) is one of the most important chemicals to the whole human society. The invention of the Haber-Bosch process enabled the industrial production of NH₃. However, owing to the high capital costs of the centralized plant and the equipment and the negative environmental impact, it is no longer suitable for today's needs of human development. As a result, there is an urgent need to investigate sustainable approaches for ammonia production. Among those reported studies, nitrogen reduction (NRR) and nitrate reduction reaction (NO₃RR) are considered applicable in the future. However, after decades of studying …

Generation Of Plasma With A Rotating Electric Field, Franklin Price Mosely

Electrical & Computer Engineering Theses & Dissertations

Nonthermal plasma generation is an important area of research that has many applications ranging from semiconductor production to medical applications including the treatment of cancers and sterilization of surfaces. Specific radicals and excited species and discharge powers are critical for the successful completion of these processes. It is important that these excited species are shown to be achievable for a given discharge system without leading to instabilities such as arcing.

The present thesis details the design, fabrication, testing, and analysis of a novel plasma generation system based on multiphase excitation. As predicted by theory, the experimental results demonstrate that a …

Application Of Direct Simulation Monte Carlo Method To Computation Of Rf Signal Degradation During Hypersonic Flight, Andrew Derubertis

McKelvey School of Engineering Theses & Dissertations

In order to further understand the hypersonic blackout problem, the first step is to investigate models to quantify signal degradation and begin implementing these models to representative plasma sheath and flow data. This research is the first attempt at implementing a model to predict RF signal degradation through the plasma sheath surrounding the hypersonic air vehicle. The investigation is performed using a Direct Simulation Monte Carlo (DSMC) based flow solver. The dsmcFoam solver in the OpenFoam library is used to simulate the flow around hypersonic bodies to obtain flow field properties, most importantly the electron number density profile, to aid …

Ambient Ammonia Synthesis Via Microwave-Catalytic Materials And Plasma Chemistry, Siobhan Brown

Graduate Theses, Dissertations, and Problem Reports

Ammonia is critical to supporting human life on earth because of its use as fertilizer. The Haber-Bosch process to produce ammonia has been practiced for over 100 years. This process operates at high pressure and temperature to overcome the thermodynamic and kinetic limitations of the ammonia synthesis reaction thus researchers have tried to overcome it for decades. At present this process represents 1% of global energy usage and 2.5% of global CO₂ emissions. The proposed chemical looping ammonia synthesis approach seeks to reduce the environmental impact of this critical process and to elucidate microwave-catalytic principles.

This research aims to …

Surface Volatilization Investigation Of Graphite, Mitchell Stern

Graduate College Dissertations and Theses

The re-entry vehicle posseses enough kinetic energy that it becomes hypersonic while passing throughthe upper atmosphere. This kinetic energy is quickly transferred into thermal energy as the quiescent atmosphere turned hypersonics with reference to the vehicle suddenly stagnates. Furthermore, the high energy process of generating plasma also ablates the leading edge surfaces, causing reactions between the charged gasses and the solid material composing the thermal protection system (TPS) of the aircraft. These reactions can be exothermic an d pose an additional mode of heat transfer into the body of the aircraft. Learning more about the interactions within the boundary layer …

Advanced Thomson Scattering Diagnostics For Various Applications, Zichen He

Doctoral Dissertations

Controlled nuclear fusion has been pursued as an ideal form of renewable energy for decades and the study of fusion plasma is fueling an increased demand for diagnostic capability. Furthermore, with the increasing applications of plasma in industry and medicine, it has become essential to characterize plasma dynamics and properties. Laser Thomson scattering diagnostics are considered to be the most reliable plasma diagnostic approaches for measuring electron temperature and electron density, the two most important parameters of a plasma. Four advanced Thomson scattering systems are discussed in this work to respectively address four different limitations or difficulties commonly encountered in …

First Development And Demonstration Of Fiber Optic Bolometer, Seungsup Lee

Doctoral Dissertations

The fiber optic bolometer (FOB) was demonstrated observing a fusion plasma for the first time, and 2D fiber optic bolometer was developed and demonstrated to have high spatial resolution. The FOB is a novel type of a bolometer that is theoretically immune to EMI. A bolometer that is a sensor that measure the power of the incoming electromagnetic radiation. The most common bolometer used in fusion research is a resistive bolometer that utilize resistors in an electrical circuit. Due to high electromagnetic interferences (EMI) in fusion environment, noise can be a serious problem in determining accurate plasma radiation. The demonstration …

Determination Of Near-Sol Carbon Impurity Content Due To Divertor Target Leakage Using Carbon-13 Tracers Via Methane Injection On The Diii-D Tokamak, Jonah David Duran

Doctoral Dissertations

Experiments with outer strike point injection of isotopically enriched methane (¹³CD­₄) in DIII-D L-mode discharges have demonstrated the ability to infer near scrape-off-layer (SOL) impurity density profiles based on: far-SOL collector probe (CP) measurements; a stable isotopic mixing model; and SOL impurity transport modelling. This work enables one of the first in-depth investigations on the source and transport of SOL impurities which could hinder performance of future fusion devices. Modelling by DIVIMP and 3DLIM of ¹³C SOL evolution is consistent with diagnostic observations and indicates that the buildup of injected impurities on plasma-facing surfaces must …

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 …

Etching Process Development For Sic Cmos, Weston Reed Renfrow

Graduate Theses and Dissertations

Silicon Carbide (SiC) is an exciting material that is growing in popularity for having qualities that make it a helpful semiconductor in extreme environments where silicon devices fail. The development of a SiC CMOS is in its infancy. There are many improvements that need to be made to develop this technology further. Photolithography is the most significant bottleneck in the etching process; it was studied and improved upon. Etching SiC can be a challenge with its reinforced crystal structure. Chlorine-based inductively coupled plasma (ICP) etching of intrinsic SiC and doped SiC, SiO2, and Silicon has been studied. A baseline chlorine …

Design And Optimization Of An Electron Cyclotron Resonance Thruster, Austen Thomas

Masters Theses

Presented in this work is the process in the design and optimization of a coaxial electron cyclotron resonance thruster. Electron cyclotron resonance thrusters are novel microwave-based thrusters which possess select technological advantages over mature electric propulsion concepts such as being electrodeless and only requiring a single power source. The thruster constructed in this work is a coaxial configuration and is termed the Western electron cyclotron resonance thruster. Thruster dimensions were optimized based on past experimentation completed with ECR thrusters. In an attempt to enhance the microwave plasma coupling of the coaxial thruster design three different antenna configurations were considered: a …

Impurity Production And Transport In The Prototype Material Plasma Exposure Experiment, Clyde J. Beers

Doctoral Dissertations

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear pulse plasma device at Oak Ridge National Laboratory with the purpose of doing the research and development for the heating concepts on the planned full MPEX device. The goal of MPEX is to perform material studies at fusion relevant conditions. To understand the conditions at the material target for performing plasma-material interaction studies the ion temperature and density, the electron temperature and density, and the particle flux and fluence must be known. Impurities within Proto-MPEX can alter the desired conditions at the material target and need to be understood for …

Droplet And Particle Dynamics In Aerosol Reactors And Environmental System, Sukrant Dhawan

McKelvey School of Engineering Theses & Dissertations

Aerosol science and engineering is an enabler for continual advances in nanomaterial synthesis. The spray-based techniques have been used extensively for the large-scale production of nanoparticles. Synthesis of particles with a desired the size and morphology is of key importance for exploiting their properties for their use in several emerging technologies. In contrast to useful nanomaterials, the aerosols from industrial flue gas, dust, indoor cooking, pathogens, and wildfire etc. are harmful to human health. It is important to understand how these harmful aerosols travel through the environment and potentially impact the health. It is also very critical to improve the …

Plasma Aerodynamics: Experimental Quantification Of The Lift Force Generated On An Airfoil Using Plasma Actuation To Estimate Power Requirements In Small Uav Applications, Getachew Ashenafi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research addressed the amount of electric power required to induce specific changes in lift force using a NACA 2127 airfoil with a chord length of ~28 mm, connected to a micro load cell, in a wind tunnel of 103 square centimeter cross-section. A DBD plasma actuator supplied by a ZVS driven high voltage pulsed DC circuit, operating at a frequency of 17.4 kHz, was utilized for voltages of up to 5000 V. Two configurations of electrode gapping were compared to determine the efficient use of power. The configuration with a gap of ~1 mm between the upstream and downstream …

Design Of Miniaturized Sweeping Langmuir Probe And Electric Field Probe For The Sport Mission, Nathan P. Tipton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Scintillation Prediction Observation Research Task (SPORT) is a joint United States of America and Brazil 6U CubeSat mission. The US is providing the science instruments and the spacecraft launch. Brazil is providing the spacecraft bus, integration, and operations. Utah State University will provide four instruments for the mission as part of the US contribution in a suite called the Space Weather Probes (SWP). These instruments are the Sweeping Langmuir Probe (SLP), the Electric Field Probe (EFP), and the Sweeping Impedance Probe (SIP). Higher frequency components of the SLP and EFP will be observed through a Wave Spectrometer (WS). These …

Absolute Number Density Measurements Of Atomic Species In Air And Nitrogen Plasmas, Jeffrey C. Schindler

Graduate College Dissertations and Theses

A vehicle reentering Earth's atmosphere at hypersonic velocities violently compresses the air in front of it, creating a shell of plasma at the surface. This plasma imparts energy onto the vehicle's surface via convective, radiative, and chemical heating. Currently, large uncertainties in measurements of surface reaction rates lead to over-designed thermal protection systems. Improvements in the precision of these measurements could substantially decrease the weight of the heat shield, freeing up space for additional fuel or human/scientific payload. This work aims to improve current methods for measurements of atomic number densities in plasmas, so that they may be applied to …

Hardware Development For The Generation Of Large-Volume High Pressure Plasma By Spatiotemporal Control Of Space Charge, Nikhil Boothpur

Electrical & Computer Engineering Theses & Dissertations

While generating a plasma under laboratory conditions, any attempt to scale the pressure and volume leads to instabilities due to the build-up of localized space-charge. This poses a challenge in the design of the discharge chamber, type of excitation field, and the type of gas that is used in the discharge. This work investigates a spatially and temporally varying electric field to control the formation of space-charge in large-volume (greater than 5 mm in the smallest dimension) near atmospheric pressure. The simulations show that in a space-charge dominated transport, the charged species disperse both in azimuthal and radial directions in …

Design And Characterization Of Low Temperature Co-Fired Ceramic Dielectric Barrier Discharge Plasma Arrays For Killing And Removing Bacterial Biofilms, Adam Croteau

Boise State University Theses and Dissertations

Present research at Boise State University (BSU) has demonstrated the ability of low temperature co-fired ceramic (LTCC) Dielectric Barrier Discharge (DBD) cold atmospheric pressure plasma (CAP) devices to remove bacterial biofilms on steel substrates. Although bacteria may easily be inactivated by plasma treatment, the remains of the organism are still present on the substrate. It is shown that single element DBD CAP discharge devices operating at 2100 Vrms with 5 LPM of hydrated argon gas etched P. fluorescens biofilm within a few minutes of exposure. Similarly, using an 8 element array of linear plasma discharges, etch removal of biofilm was …

Investigating Newly Discovered Oscillation Modes In Magnetically Shielded Hall Effect Thrusters Utilizing High Speed Diagnostics, Matthew Joseph Baird

Dissertations

Magnetically shielded Hall effect thrusters (MSHETs) are a variant of Hall effect thrusters (HET) that provide the favorable thrust-to-power ratio and high specific impulse of traditional stationary plasma type (STP) HETs but with an extremely long lifetime. MSHETs exhibit unique discharge plasma oscillations compared to traditional unshielded HETs. In this study, measurements of plasma oscillations in the state-of-the-art 12.5 kW Hall Effect Rocket with Magnetic Shielding (HERMeS) were obtained at various discharge voltages while holding other operation parameters constant. Data were collected using high-speed imaging, voltage, current, and plasma probes. The thruster exhibits two dominant oscillation modes within the discharge …

Design Of A Sweeping Impedance Probe For The Sport Mission, Caleb W. Young

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In our modern world satellite systems are an evermore common part of day to day life. Reliable communication from the ground to these satellites is becoming more and more necessary. Plasma scintillations in the ionosphere can make these communications difficult or even impossible. By gaining a better understanding of these scintillations, times of bad satellite connection can be predicted in the same way terrestrial weather gets predicted and reported today. The objective of the SPORT mission is to gain a better understanding of these plasma scintillations. In order to measure plasma density, and gain a better understanding of plasma scintillations, …

Electrical And Chemical Characterization Of A Helium-Air Non-Thermal Atmospheric Pressure Plasma Jet, Adam Zandani

Seton Hall University Dissertations and Theses (ETDs)

Plasma is one of the most complicated, yet promising fields in physics due to its high efficiency and multitude of crucial applications such as biological sterilization, polymer modification, surface treatments, etching, agriculture, and facilitation of selective catalytic processes to name a few. With these advantages, mysteries still remain. With this in mind, in order to accurately gauge the total influence of the plasma applied in various processes, understanding what is being produced and how the production occurs is vital. To understand this, optical emission spectroscopy was used to gauge how the species generated are influenced by operation parameters such as …

Design And Testing Of A Supercritical Carbon Dioxide Plasma Reactor, Gregory Belk

Theses and Dissertations

The objective of this project was to design, build, and test a plasma reactor capable of operating in the supercritical conditions. The reactor allows for the initiation of a plasma discharge in different fluids driven by a direct current (DC) power supply operating either in steady state mode or pulsing mode. The reactor was specifically designed for igniting plasmas within supercritical carbon dioxide, which has a pressure of 72.9 atm and 31.1 degrees Celsius.

A series of runs were conducted for varying pressures and inter-electrode separation, which allowed testing the operation regimes of the reactors. Finally, plasma experiments were conducted …

Characterization Of A Plasma Source Simulating Solar Wind Plasma In A Vacuum Chamber, Blake Anthony Folta

Masters Theses

"The United States has set an aggressive time line to not only return to the Moon, but also to establish a sustained human presence. In the Apollo missions dust was a significant factor, but the duration of those missions was short so dust and surface charging were problems, but they did not pose an immediate threat. For a long-term mission, these problems instead become incredibly detrimental. Because of this, research needs to be conducted to investigate these phenomena so that mitigation techniques can be developed and tested. To this end, this thesis serves to demonstrate the Gas and Plasma Dynamics …

A Homegrown Dsmc-Pic Model For Electric Propulsion, Dominic Charles Lunde

Master's Theses

Powering spacecraft with electric propulsion is becoming more common, especially in CubeSat-class satellites. On account of the risk of spacecraft interactions, it is important to have robust analysis and modeling tools of electric propulsion engines, particularly of the plasma plume. The Navier-Stokes equations used in classic continuum computational fluid dynamics do not apply to the rarefied plasma, and therefore another method must be used to model the flow. A good solution is to use the DSMC method, which uses a combination of particle modeling and statistical methods for modeling the simulated molecules. A DSMC simulation known as SINATRA has been …

Experiment And Computational Analysis On Effect Of Plasma Actuation Incompressible Flow Around Tandem Cylinders, Emmanuel C. Gabriel-Ohanu

Honors Undergraduate Theses

The utilization of steady state flow of air over tandem circular cylinders has several applications in engineering systems. Incompressible flow over circular cylinders in tandem at different spacing with and without plasma actuation on the leading cylinder will be investigated in this paper to understand the effects of plasma actuation on flow properties and wake region of the two cylinders in cross flow. The principal focus of the research is on the use of experimental and computational methods to study and provide valid results, the research will analyze the wake region, the effect of Reynolds number and the longitudinal spacing …

Micro-Nozzle Simulation And Test For An Electrothermal Plasma Thruster, Tyler J. Croteau

Master's Theses

With an increased demand in Cube Satellite (CubeSat) development for low cost science and exploration missions, a push for the development of micro-propulsion technology has emerged, which seeks to increase CubeSat capabilities for novel mission concepts. One type of micro-propulsion system currently under development, known as Pocket Rocket, is an electrothermal plasma micro-thruster.

Pocket Rocket uses a capacitively coupled plasma, generated by radio-frequency, in order to provide neutral gas heating via ion-neutral collisions within a gas discharge tube. When compared to a cold-gas thruster of similar size, this gas heating mechanism allows Pocket Rocket to increase the exit thermal velocity …

Decomposition And Ionization Of Ionic Liquids, Forrest Grady Kidd Iii

Dissertations

The United States Air Force is interested in developing a situationally responsive space environment. In order to achieve this, dual-mode-propulsion will be utilized. A new class of propellants is being developed for this application based on energetic ionic liquids. Two ionic liquids of current interest are Hydroxylammonium Nitrate (HAN) and Hydroxyethylhydrazinium Nitrate (HEHN) due to their beneficial performance characteristics. The decomposition and ionization chemistry of these two species is investigated in this work. Using GAUSSIAN09 software, reactions with important radicals are explored through quantum chemistry. The energetics of reactions as well as the identity of key product complexes are given. …

Thermal Modelling And Validation Of Heat Profiles In An Rf Plasma Micro-Thruster, Alec Sean Henken

Master's Theses

The need and demand for propulsion devices on nanosatellites has grown over the last decade due to interest in expanding nanosatellite mission abilities, such as attitude control, station-keeping, and collision avoidance. One potential micro-propulsion device suitable for nanosatellites is an electrothermal plasma thruster called Pocket Rocket. Pocket Rocket is a low-power, low-cost propulsion platform specifically designed for use in nanosatellites such as CubeSats. Due to difficulties associated with integrating propulsion devices onto spacecraft such as volume constraints and heat dissipation limitations, a characterization of the heat generation and heat transfer properties of Pocket Rocket is necessary. Several heat-transfer models of …

Experimental Verification Of A6 Magnetron With Permanent Magnet, Andrew J. Sandoval

Electrical and Computer Engineering ETDs

A compact A6 relativistic magnetron with diffraction output using a transparent cathode, simple mode-converter, and a permanent magnet were simulated and tested at the University of New Mexico (UNM) for the Office of Naval Research. The standard compact MDO with a simple mode converter and transparent cathode radiates a TE11 mode axially through a cylindrical horn antenna. The magnetic field, essential for magnetron operation, is provided by a Neodymium Iron Boron (NeFeB) GradeN40M rare earth magnet. The permanent magnet eliminates the need for a pulsed magnet and accompanying circuit, significantly reducing the size of the system. A permanent magnetic field …

Pseudo Linear Hall Effect Thruster Characterization Through Potential, Magnetic, And Optical Measurements, Braeden A. Sheets

Theses and Dissertations

Electric propulsion systems are a more mass efficient method for providing a change in velocity, ΔV, to on-orbit spacecraft, than their chemical counterparts. In comparison, electric systems generally have a much higher specific impulse, Isp, than chemical systems. One option within the realm of electric propulsion is Hall Effect Thrusters, which have moderately high specific impulse values. From their advent in the 1960s, Hall Effect Thrusters have been used for orbit station keeping, attitude control, and orbit transfer. Although the discharge cavity is conventionally circular, pseudo-linear or racetrack shaped cavities have been developed. Even though Hall thrusters have decades of …