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 distribution"”.
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Determination of the ion distribution function during magnetic reconnection in the versatile toroidal facility with a gridded energy analyzer
… are designed and built to explore the evolution of the ion distribution function during driven magnetic reconnection in the Versatile Toroidal Facility. The temporal evolution of the ion characteristic is measured at different locations throughout the reconnection region, for a number of …
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Experimental measurements and numerical modeling of fast-ion distributions in the Alcator C-Mod Tokamak
… and modeling of minority heated fast-ion distributions in the Ion Cyclotron Range of Frequencies (ICRF) on the Alcator C-Mod tokamak. Analysis of fast-ions >100Te is important for both ITER and a future fusion reactor as both will have a significant population of 3.5 MeV alpha …
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Resonant wave-ion interactions in the heliosphere: I. Interplanetary traveling shocks, II. Ion heating and acceleration in the extended corona
<p>In Part I we present a revised version of the self-consistent theory of ion diffusive shock acceleration and associated generation of hydromagnetic waves at a planar stationary shock. Coupled wave kinetic and energetic particle transport equations are solved numerically and compared with an …
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Construction of a gridded energy analyzer for measurements of ion energy distribution in the versatile toroidal facility
… Facility (VTF) at MIT's Plasma Science and Fusion Center provides a laboratory environment for studying ionospheric plasmas. Various plasma diagnostic devices have been created and used to study the VTF plasma since 1991. An accurate method for measuring VTF's ion characteristics has never been …
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Collisionless ion collection by non-emitting spherical bodies in E x B fields
The three-dimensional interaction of a magnetized, collisionless flowing plasma with a non-emitting conducting sphere is solved in the entire range of physically allowed parameters, in the ion-collecting regime. This can be considered as the "spherical Mach probe" problem, establishing how the ion …
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Predictive modeling of soluble sulfate ion concentration in the Las Vegas Valley
… the process of identifying soluble sulfate ion concentrations in the Las Vegas Valley. Data utilized in this study were obtained from Clark County Department of Development Services records. Once collected, the data were reviewed and analyzed with traditional non-spatial statistics and …
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Isothermal model of ICF burn with finite alpha range treatment
… tritium burn in inertial confinement fusion capsules is developed. The model, called the Isothermal Rarefaction Model, is zero dimensional (represented as ordinary differential equations) and treats disassembly in the isothermal limit. Two substantive theoretical developments are …
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Hybrid-PIC modeling and electrostatic probe survey of Hall thrusters
In order to study the physics of the acceleration process in Hall thrusters, an evolved hybrid particle-in-cell (PIC) numerical model was developed. A set of quasi-one-dimensional fluid equations are used for electrons, and a particle-tracking Boltzmann solver is used for the heavy species. The two …
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Selective salt recovery from reverse osmosis concentrate using inter-stage ion exchange
… fresh water recovery. The process utilizes cation and anion exchange to exchange all ions in the concentrate stream for sodium and chloride. The sodium chloride stream, with reduced scaling potential, can be treated further by a second reverse osmosis stage or another volume reduction technique …
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Analytic calculations of MHD equilibria and of MHD stability boundaries in fusion plasmas
… are considered. In the first part, analytic solutions to the Grad-Shafranov equation (GSE) are presented, for two families of source functions: functions which are linear in the flux function T , and functions which are quadratic in T. The solutions are both simple and very versatile, since they …
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Collisionless ion collection by a sphere in a weakly magnetized plasma
The interaction between a probe and a plasma has been studied since the 1920s and the pioneering work of Mott-Smith and Langmuir [1], and is still today an active topic of experimental and theoretical research. Indeed an understanding of the current collection process by an electrode is relevant to …
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Modeling Differential Charging of Composite Spacecraft Bodies Using the Coliseum Framework
… framework is a tool designed for electric propulsion plume interactions. Virginia Tech has been developing a module for COLISEUM called DRACO, a particle-in-cell based code capable of plume modeling for geometrically complex spacecraft. This work integrates a charging module into DRACO. Charge is …
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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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Interstellar helium pickup ion flux variations observed with SOHO/CELIAS
<p>Interstellar pickup ions are formed when neutral atoms freely enter the heliosphere and are subsequently ionized. Once these particles are charged they become a component of the interplanetary plasma and are transported outward with the solar wind (SW). Measurements of these particles give …
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MODELLING POLYMER-INDUCED ADHESION BETWEEN CHARGED MEMBRANES: THEORETICAL AND COMPUTATIONAL APPROACH
… and extensive coarse grained MD simulations the adhesion between two identical planar charged surfaces embedded in a uncharged polymer-containing electrolyte solution. The solution mimics physiological fluids: It contains 0.1 M of mono-valent ions and a small number of divalent cations …
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Biomedical applications of nanostructured polymer films
Functional polymeric thin films are often stratified with nanometer level structure and distinct purposes for each layer. These nanostructured polymeric materials are useful in a wide variety of applications including drug delivery, tissue engineering, controlling condensation and polymeric …
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Finite drift orbit effects in a tokamak pedestal
… Confinement Mode" or "H Mode" of tokamak operation. This region is characterized by a drastic plasma density drop over a relatively short radial distance, typically of order of the poloidal ion gyroradius (p,,). Experiments demonstrate that H Mode plasmas have superior transport properties …
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Mass spectrometry imaging for probing molecular distributions in the nervous system
… a highly intertwined and complex set of interactions in which molecules vary spatially and temporally in addition to being present in concentrations that extend over many orders of magnitude. These chemical entities belong to numerous classes including inorganic salts, metabolites, lipids, …
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Self-reporting of Mn ion dissolution and self-stabilization of cathode-electrolyte interface in lithium ion batteries
Battery degradation limits the lifespan of energy storage devices. This dissertation focuses on developing self-reporting strategies that enable in situ or operando characterization of cathodic Mn dissolution, which is a major cause of the capacity fade for some cathodes, and release of battery …
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Static and dynamic properties of soluble surfactants at the air/water interface
… a hydrophobic tail. The headgroup is polar or ionic and likes water, the tail is typically an aliphatic chain that cannot be accommodated in a polar environment. The prevailing molecular asymmetry leads to a spontaneous adsorption of amphiphiles at the air/water or oil/water interfaces. As a …
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