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 44 for “"Ion Temperature"”.
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Direct Ion-Temperature Measurements Using High-Resolution Inelastic X-ray Scattering
Temperature in high-energy-density (HED) materials has been a long-standing problem. Direct temperature measurements are challenging because HED samples are often opaque and have extremely short lifetimes. Historically, ion temperature has been inferred from structural measurements that serve only …
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Measuring the Ion Temperature of a Plasma Jet Undergoing Instability-Driven Heating
<p>Outlined are arrangements to measure the ion temperature of a plasma jet undergoing instabilities and an examination of experiment findings. The jet, formed by puffing a controlled amount of Nitrogen or Argon gas into Embry-Riddle's cylindrical vacuum chamber and then ionizing it via …
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A study on the ion temperature gradient driven turbulence in tokamak plasmas
… growth of the energy worldwide consumption is one of the most important challenges to our civilization. New kinds of energy resources are without doubt needed. Nuclear fusion promises to supply large amounts of energy, with minimal environmental impact. This has motivated at least sixty …
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D-D fusion neutron spectra measurements and ion temperature determination at Alcator C
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1983.
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Velocity-ion temperature gradient driven modes and angular momentum transport in magnetically confined plasmas
… phenomena that motivate theoretical discussion and exploration. In this thesis, we consider the phenomenon of angular momentum transport in magnetically confined plasmas. Relevant experiments and theoretical developments are presented in order to motivate the derivation of a modified version …
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F-region Dusk Ion Temperature Spikes at the Equatorward Edge of the High Latitude Convection Region
… Alaska, short-lived enhancements in the F-region ion temperature, or "Tᵢ spikes", were discovered in the evening while the radar was on the equatorward edge of the high latitude convection region. These enhancements were several hundred Kelvin above the background temperature, would last less …
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Finite Ion Temperature, Plasma Rotation, and Electromagnetic Effects on Plasma Acceleration in the Magnetic Mirror Geometry
Converging-diverging magnetic field configurations (such as magnetic mirrors and mag-netic nozzles) are employed in various functions for nuclear fusion, electric propulsion, and material processing applications. The physics underlying the dynamics of plasmas in such geometries is not fully …
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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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Depletion, quantum jumps, and temperature measurements of ⁸⁸Sr⁺ ions in a linear Paul Trap
This thesis describes the design and construction of two laser systems to probe the 674nm transition of ⁸⁸Sr⁺ ions in a linear Paul trap. The first laser system made use of a molecular transition in Iodine to stabilize the length of a Fabry-Perot cavity for laser locking. After constructing this …
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Probes in gaseous plasmas
… a small electrode probe immersed in a partially ionised gas have been used for the quantitative study of plasmas. The plasma parameters of interest are electron and ion temperature, electron and ion concentration, and plasma potential.
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Development of probes for assessment of ion heat transport and sheath heat flux in the boundary of the Alcator C-Mod Tokamak
Progress towards a viable fusion reactor will require comprehensive understanding of boundary plasma physics. Knowledge in this area has been growing, yet there are critical gaps. Measurements of the sheath heat flux transmission coefficient-a fundamental physical quantity whose theoretical value …
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Turbulence and transport studies with phase contrast imaging in the Alcator C-Mod tokamak and comparisons with gyrokinetic simulations
… system is capable of measuring density fluctuations with high temporal (2 kHz-5 MHz) and wavenumber (0.5-55 cm-1) resolution. An upgrade of the system has enabled PCI to localize the short wavelength turbulence in the electron temperature gradient (ETG) range and resolve the direction of …
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Characterization of ion properties in a linear pulsed plasma-material interaction test stand
In the edge and divertor regions of the magnetically confined plasma, tokamaks experience off-normal events in which high intensities of heat flux incident on wall component surfaces result in intolerable levels of damage. Proposed solid divertors will not be able to withstand these fluxes, …
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Impact of ion-neutral collisions in fluid models of plasma sheath
… thesis, the development of an improved one-dimensional self-consistent fluid modeling of argon plasmas in DC discharges, including the sheath regions, is presented. Comparison of the charged species density, electron mean energy, plasma potential and ion velocity profiles with the profiles …
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Local transport analysis for the Alcator C-Mod tokamak
… of the scaling of transport with P*, the ion Larmor radius normalized to the plasma size. The second was a comparison of the transport predictions from the IFS-PPPL model of ion temperature gradient (ITG) driven turbulence to observations on C-Mod. The P* scaling experiments on C-Mod …
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Characterization of main ion properties for the optimization of future fusion power plants
… sustainable energy source for our society, fusion energy emerges as a promising candidate. The realization of a fusion power plant on Earth faces important technological and physical challenges. This thesis is a multidisciplinary project that addresses the optimization of future fusion devices …
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Resonant ion heating in a helicon plasma
A resonant ion heating system has been developed for heating ions and controlling the ion temperature anisotropy in a helicon plasma source. The system uses two rectangular coils placed on either side of the cylindrical pyrex vacuum chamber to create a time dependent magnetic field transverse to …
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Comparing Solution-Phase and Gas-Phase Protein Stability Using Ion Mobility and Differential Mobility Mass Spectrometry
… assays to determine the proteins melting temperature include thermal ramps of a protein using a fluorescent dye to monitor unfolding. Protein unfolding has also been studies with mass spectrometry through collision induced unfolding (CIU) whereby the ion temperature in the trap collision …
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Development and Test of a Permanent Magnet Helicon Thruster
… impulse of 1400 seconds. Analysis of the variation of beam power and ion temperature in the exhaust plume with variation of input power and vacuum pressure are presented. Preliminary tests were conducted using water as a propellant. Measurement of the ion energy distribution function shows a …
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Studies of electron temperature fluctuations in the core of Alcator C-Mod plasmas via correlation electron cyclotron emission
… believed to be attributed to turbulent fluctuations. New Correlation Electron Cyclotron Emission (CECE) experiments on Alcator C-Mod show lower levels of electron temperature fluctuations in the saturated ohmic confinement (SOC) regime than in the linear ohmic confinement (LOC) regime, however …
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