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 36 for “"Plasma flow"”.
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High speed plasma flow about probes
… inviscid, electrically conducting ideal gas flow past a blunt body is presented. An experiment using a double diaphragm shock tube to produce a slug of gas with high electrical conductivity is performed to confirm the theoretical results. The theoretical problem is considered in two parts. …
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High speed plasma flow about probes
… inviscid, electrically conducting ideal gas flow past a blunt body is presented. An experiment using a double diaphragm shock tube to produce a slug of gas with high electrical conductivity is performed to confirm the theoretical results. The theoretical problem is considered in two parts. …
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Measurements on supersonic plasma flow in a diverging channel
… which explains the test results. Since the flow is partially ionized, the effect of catalytic and non-catalytic wall materials on nozzle performance is also investigated.
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Plasma flow and acceleration in the magnetic mirror and nozzle geometries
… investigates key physics governing transonic plasma flow within converging-diverging magnetic field (magnetic nozzle) configurations as used in fusion open mirror systems and plasma propulsion applications. In such configurations, plasma is accelerated from subsonic to supersonic velocities …
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Plasma flow in the magnetosphere under the influence of large scale electric field
The plasma flow is obtained by setting up a mathematical model, using the most appropriate geomagnetic field model and adopting the idea of equivalent potential in the magnetosphere The field model consists of four components: 1) Dipole main field; 2) Dayside magnetosphere boundary current; 3) …
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Physics and application of impurity plume dispersal as an edge plasma flow diagnostic on the Alcator C-Mod tokamak
… for studying impurity transport in the edge plasma of Alcator C-Mod. Impurity gas (which for these experiments is deuterated ethylene, C₂D₄) is injected locally into the scrape-off layer (SOL) through the end of a reciprocating fast-scanning probe, and the resultant emission ("plume") is …
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Design of Optical Measurements for Plasma Actuators for the Validation of Quiescent and Flow Control Simulations
The concept of plasma flow control is a relatively new idea based on using atmospheric plasma placed near the edge of an air foil to reduce boundary layer losses. As with any new concept, it is important to be able to quantify theoretical assumptions with known experimental results for validation. …
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Experimental Studies of Spacecraft Plasma Interactions: Facility Characterization and Initial Measurements
… of this thesis are to characterize the plasma environment of a new vacuum chamber facility at Virginia Tech and to perform initial measurements of plasma flow field for studying spacecraft-plasma interactions using this facility. An argon plasma environment was created using a hot …
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Plasma flows in the Alcator C-Mod scrape-off layer
Near-sonic parallel plasma flows are persistently observed in the scrape-off layer (SOL) of tokamaks, at locations far from material surfaces. Ballooning-like transport asymmetries are thought to be a principal driver for the strong parallel flows, a hypothesis supported by the observation of steep …
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Immersed Finite Element Particle-In-Cell Modeling of Surface Charging in Rarefied Plasmas
… is a fundamental interaction process in space plasma engineering. A three-dimensional Immersed Finite Element Particle-In-Cell (IFE-PIC) method is developed to model surface charging involving complex boundary conditions. This method extends the previous IFE-PIC algorithm to explicitly include …
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Theoretical studies of the VASIMR plasma propulsion concept
… by the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) project. The VASIMR device has a magnetic mirror configuration and consists of three main components: a low energy helicon plasma source, which creates cold plasma via rf-discharge; an ion cyclotron-resonance heating (ICRH) …
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Immersed Finite Element Particle-In-Cell Simulations of Ion Propulsion
… new particle-in-cell algorithm was developed for plasma simulations involving complex boundary conditions. The new algorithm is based on the three-dimensional immersed finite element method which is developed in this thesis, and a modified legacy particle-in-cell code. The model also applies a new …
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Extension of gyrokinetics to transport time scales
… The radial electric field, closely related to plasma flow, is known to have a considerable impact on turbulence saturation, and any self-consistent global simulation of turbulent transport needs an accurate procedure to determine it. In this thesis, I study the effect of turbulence on the …
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Nonlinear gyrokinetic simulations of intrinsic rotation in up-down asymmetric tokamaks
Experiments and theory show that tokamak plasmas with strong toroidal rotation and rotation shear can suppress turbulent energy transport as well as allow violation of the Troyon [beta] limit. However, using external neutral beams to inject toroidal momentum, as is done in many current experiments, …
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Laboratory Experiments of High-Energy-Density Shocks in Magnetized Supersonic Plasma Flows
… environments, in which high Mach number flows interact with ambient media, planetary obstacles, and/or spacecraft to generate strongly radiating shocks. Some examples include extrastellar jets from radio galaxies, relativistic jets from quasars and blazars, Herbig-Haro jets from Young …
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Dynamische Stabilisierung von Hochgeschwindigkeitswolken im galaktischen Halo
… in a hot, thin, and magnetized ambient halo plasma is addressed. The results of two-dimensional plasma-neutral gas simulations showing the dynamical evolution of neutral gas clouds in a plasma flow are presented. The simulations show the formation of a comet-like head-tail structure combined …
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Study of magnetohydrodynamic effects for the Richtmyer-Meshkov instability
… its growth, but rather developes an atmospheric plasma jet for use in future magnetohydrodynamic experiments. The operating conditions of the torch are explored to optimize the ionized length of the plasma jet by varying the voltage-current characteristics and the gas low rates. Probe, spectral, …
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Plasma Properties and Heating at the Anode of a 1 kW Arcjet Using Electrostatic Probes
… arc}$, between 7.8 and 10.6 A, propellant flow rates m = 40-60 mg/s, and specific energies, 18.8 MJ/kg $\le$ P/m $\le$ 27.4 MJ/kg; (2) probe the anode boundary layer using flush-mounted and cylindrical micro-probes; (3) verify azimuthal current symmetry; (4) understand what affects anode …
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Ionospheric Disturbances: Midlatitude Pi2 Magnetospheric ULF Pulsations and Medium Scale Traveling Ionospheric Disturbances
… (ULF) pulsations in the vicinity of the plasmapause. Prior to these pulsations, two Earthward moving fast plasma flows were detected by spacecraft in the magnetotail. Signatures of inner magnetospheric compression observed by the Blackstone radar provide conclusive evidence that the …
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