Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"ion density"”.
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ELECTROSTATIC (LANGMUIR) PROBE MEASUREMENTS IN RF DRIVEN He, N2, BCl3, AND BCl3/N2 PLASMAS
… system was developed to measure the electron density distribution in BCl3/N2 mixtures to determine if an average electron energy increase might be partially responsible for the previously observed etch rate enhancement of GaAs with nitrogen addition. The system was validated in both helium and …
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Plasma Diagnostics of Discharges in Nitrogen-Trifluoride (Etching, Semiconductor)
This work has dealt with an investigation of the nitrogen trifluoride etchant gas discharge and has demonstrated a variety of diagnostic techniques applicable to all plasmas used for semiconductor processing. By monitoring the change of the mass spectrum ion signals when the discharge was …
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A polarized helium ion beam for surface electronic structure studies
… describes the development of a spinpolarized He+ ion beam suitable for use as a- probe of surface electronic structure of metals. The method would represent an extension of ion neutralization spectroscopy (INS), and should provide new information on surface magnetism, electron correlation effects, …
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Bombardment of Thin Lithium Films With Energetic Plasma Flows
Here, we present experimental verification of substantially reduced target surface temperature with the use of thin lithium films on surface of the target as compared to a bare target. Furthermore, optical measurements are made to determine the density and temperature of the lithium vapor cloud as …
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A Framework for Validation and Testing of a CubeSat Retarding Potential Analyzer
Traditionally, Retarding Potential Analyzers (RPAs) operate exclusively on large satellites due to the size, power, and mass constraints posed by nano-satellites like CubeSats. These sensors take in-situ measurements of Earth's atmospheric ion current during a range of time-varied ``retarding" …
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Plasma Dynamics in a High-Power Helicon Source
The magnetically confined plasma in the ITER fusion reactor must reach temperatures over 100 million kelvin to sustain fusion reactions. Neutral Beam Injectors (NBIs) will provide most of the heating power by accelerating negative ions to energies of 1 MeV, where they are then neutralised to …
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Plasma Dynamics in a High-Power Helicon Source
The magnetically confined plasma in the ITER fusion reactor must reach temperatures over 100 million kelvin to sustain fusion reactions. Neutral Beam Injectors (NBIs) will provide most of the heating power by accelerating negative ions to energies of 1 MeV, where they are then neutralised to …
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Design, construction, and characterization of an ultra-sensitive, high-precision fast ion-beam spectrometer for the study of molecular ions
This dissertation details the design, construction and characterization of a sensitive, fast ion beam spectrometer to record the absorption spectra of molecular ions. It is the first work to use the noise immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) technique in …
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Developing Fixed-Bias Langmuir Probes for Multi-Point Constellation Deployments
… invaluable in terrestrial and interplanetary ionospheric sounding applications. When deployed aboard rocket and satellite platforms, these probes yield high-cadence, in-situ measurements of key plasma parameters such as electron density, ion density, and electron temperature. Furthermore, the …
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Under confinement : molecular dynamics investigations of ions and molecules in nanopores and at nanoscale interfaces.
… of fundamental importance in chemical applications such as electrical energy storage and water desalination. Investigations into carbon based structures such as carbon nanotubes and graphene sheets with confined fluids are promising for the enhancement of such technologies. Through molecular …
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Interactive visualization framework for space plasma data sets
… understanding of space physics. However, traditional visualization tools used in the space science community are either proprietary, lack portability or require paid license subscriptions. Therefore we are attempting to resolve these shortcomings by developing cross-platform, free-to-use, easily …
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Electronics for a Versatile and Robust Retarding Potential Analyzer for Nano-Satellite Platforms
… low-Earth orbit, makes in-situ measurements of ion density, temperature and speed relative to the satellite frame. The instrument works by changing the voltage on one of a set of grids and measuring a corresponding current generated by ions flowing through the grid, generating a function of …
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Physics and application of impurity plume dispersal as an edge plasma flow diagnostic on the Alcator C-Mod tokamak
… fast-scanning probe, and the resultant emission ("plume") is imaged from two near-perpendicular views. Plumes are generated at various SOL depths, while views are obtained using coherent fiber bundles optically coupled to gated, intensified CCD cameras through beam-splitters, allowing for the …
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Fundamental properties of a microwave induced argon plasma
… Spectroscopic measurements of twenty one emission lines of the argon I spectrum and seven lines of the argon II spectrum are combined with microwave impedance and Langmuir probe measurements. The population densities of some seventeen levels of the argon atom are evaluated and the results …
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Kinetic Modeling of Ionospheric Outflows Observed by the VISIONS-1 Sounding Rocket
<p>Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion …
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Turbulence and transport measurements in Alcator C-Mod and comparisons with Gyrokinetic simulations
… it is lost, and is therefore the main limitation of tokamak plasma performance. Dilution of the main-ion species was found to have a stabilizing effect on ion gyroradius scale turbulence in tokamak plasmas. Dilution of deuterium tokamak plasmas is the reduction of the ratio of the deuterium …
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Nearly Monoenergetic Positive Ion Beam with Self-Neutralized Space Charge Extracted from a Pulsed Plasma and Its Application
Space charge neutralization of an ion beam extracted from a plasma is crucial for advanced plasma processes which require precise control of the ion flux and the width of the ion energy distribution (IED). In previous studies, filaments thermionically emitting electrons were used for neutralizing …
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Nanoscale Liquid Dynamics in Membrane Matrices: Insights into Confinement, Molecular Interactions, and Hydration
This dissertation focuses on the fundamental understanding of liquid dynamics confined in polymer membranes. Such knowledge guides the development of better polymer membranes for practical applications and contributes to the general understanding of confined liquid dynamics in various nanoporous …
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Test particle studies of acceleration and transport in solar and tokamak plasmas
… used to study two distinct plasma physics situations. In the first case, the collisionless response of protons to cold plasma fast Alfven waves propagating in a non-uniform magnetic field configuration (specifically, a two-dimensional X-point field) is studied. The field perturbations associated …
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High power impulse magnetron sputtering (HIPIMS) : Fundamental plasma studies and material synthesis.
Physical vapour deposition (PVD) technology is widely used for deposition of coatings with applications in various industries; coatings in semiconductor industry, optical coatings or hard coatings mostly used in car and aerospace industries. In 1999 novel physical vapour deposition technology …
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