This thesis reports observations of kink and tearing modes in the High Beta Tokamak - ExtendedPulse (HBT-EP) experiment. When unstable, these modes could limit the operation of tokamaks used for fusion power by terminating the plasma discharge and causing rapid loss of plasma energy. The aim of this work is to characterize the sudden transition after a sawtooth crash of coupled 2/1-3/1 tearing-kink modes into a sustained and disruptive 2/1 tearing mode. The following diagnostic techniques are used. Kink and tearing modes in HBT-EP distort the plasma edge, measured by a large array of Mirnov sensors, and perturb the interior of the plasma, observed routinely with Extreme Ultraviolet (EUV) detector arrays. Two arrays, with different transmission filters, are located with tangential views to estimate the time evolution of the plasma temperature profile. Four EUV arrays, with 16 detectors each, are positioned with different poloidal views for poloidal Extreme Ultraviolet (pEUV) emission tomography. The 2D emissive structures producing the pEUV signals are reconstructed with tomographic inversion using a pixel basis and fixed weighting smoothness regularization. Spatial and temporal correlations across these independent diagnostics are used to measure the evolution and structure of coupled modes using a technique called multidiagostic Singular Value Decomposition (mdSVD). In mdSVD, orthogonal modes are identified within any fixed time window with their unique spatial and temporal characteristics. The technique uncovers: coherent behavior of coupled (𝑚/𝑛) = (2/1) and (3/1) tearing-kink modes and rapid changes in plasma structure associated with sawtooth crashes which trigger disruptive and nondisruptive tearing modes. HBT-EP’s unique radially movable wall is found to significantly influence sawtooth triggering of disruptive tearing modes. The onset of sawtooth-triggered modes depends both on the plasma-wall separation, or wall coupling, and on the value of edge safety factor qₐ. We confirm that the condition for sawtooth triggering of disruptive (𝑚/𝑛) = (2/1) tearing modes does not correspond to the mode’s single-helicity stability condition Δ′₂/₁. We identify a dependency of the sawtooth period 𝝉_𝑠𝑡 on the wall position and qa as a candidate to explain the onset of the saturated tearing mode. This thesis motivates future efforts to model the influence of a nearby resistive wall on sawtooth triggering of tearing modes.

Desenvolvemos urna teoria cinética para urna mistura de gases ionizados em presença de campos elétricos e magnéticos. As leis de Ohm, Fourier e Navier-Stokes são obtidas por dois métodos distintos que se baseiam na equação de Boltzmann. Verificamos que o emprego de teoremas de representação torna o método de Chapman-Enskog mais direto. Entretanto o método combinado mostrou-se extremamente simples, onde os coeficientes de transporte são determinados através da inversão de tensores de segunda e quarta ordens. Calculamos também a integral de colisão para as possíveis interações em gases ionizados tais como, entre partículas carregadas, partícula carregada e partícula neutra e entre partículas neutras. Como uma aplicação do método combinado, determinamos os coeficientes de condutividade elétrica, condutividade térmica, coeficiente termo-elétrico e o coeficiente de viscosidade cisalhante para um gás totalmente ionizado. Obtemos seus respectivos gráficos, considerando então um gás ionizado formado a partir do gás de hélio. / We develop a kinetic theory for ionized gases mixtures under the presence of electric and magnetic fields. The laws of Ohm, Fourier and Navier-Stokes are obtained by two different methods based on the Boltzmann equation. We verify that the use of representation theorems makes the Chapman-Enskog method more direct. However the combined method shows up as extremely simple where the transport coefficients are determined through inversion of second-order and fourth order tensors. We calculate also the collision integrals for possible interactions in ionized gases like: between charged particles, between charged particles and neutral particles and between neutral particles. As an application of the combined method, we determine the electrical and thermal conductivity coefficients, thermo-electric and shear viscosity coefficients for a completely ionized gas. We obtain their respective graphics considering an ionized gas of helium.

"December 2004" / Includes bibliographical references. / 2 v. (various pagings) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Sc.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005

Resonant Magnetic Perturbation (RMP) fields produced by external control coils are considered a viable option for the suppression of Edge Localized Modes (ELMs) in present and future tokamaks. Repeated reversals of the toroidal phase of the I-coil magnetic field in RMP shot 147170 on DIII-D has generated uniquely different edge pedestal profiles, implying different edge transport phenomena. The causes, trends, and implications of RMP toroidal phase reversal on edge transport is analyzed by comparing various parameters at 0 and 60 degree toroidal phases, with an I-coil mode number of n=3. An analysis of diffusive and non-diffusive transport effects of these magnetic perturbations it the plasma edge pedestal for this RMP shot is characterized by interpreting the ion and electron heat diffusivities, angular momentum transport frequencies, ion diffusion coefficients, and pinch velocities for both phases.

Graphite Furnace Atomic Absorption Spectroscopy (GFAA) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) are two primary means of analyzing metals at the elemental level. Both techniques are widely accepted as tools for basic research. Each technique is performed differently and has its own distinct advantages as well as disadvantages. The choice of which technique to employ is determined by the needs of the analysis and the limitations of the instrumental technique.The idea to merge the two techniques was originallydeveloped by the research group of Dr. Michael W. Blades of the University of British Columbia, Vancouver, in 1989, who successfully demonstrated a "mini" plasma within a graphite furnace. The goal of the research was to design a device that would combine the advantages of both techniques and hopefully eliminate or minimize the unfavorable characteristics of each technique.The sustaining of a "mini" plasma has been demonstrated by this group. Although the end result was similar to that of Blades' group, the method of achieving the plasma was such that the "new" instrument could easily be mounted onto the furnace via a small Interface/Power Coupling device. The advantages of this system are: existing GFAA instruments can be used; modification of the furnace and RF supply is minimal; RF electronics can be remotely located; removal of the interface device is quickly achieved; and sample introduction, through the use of an autosampler, can be facilitated with small modification.Background spectra were acquired using helium, argon, and a mixture of argon/helium. It was found that all the plasmas have highly structured backgrounds and demonstrate the potential for many analysis regions. Two methods of sample introduction were used in acquiring the line emission of magnesium: injection through the sample inlet port to the furnace and end window injection. Inlet port injection suffers from a loss of sensitivity, when compared to end cap injection, but is more easily performed. / Department of Chemistry

In the last decade, ultracold plasmas have been created in the laboratory by photo-ionizing laser-cooled atoms. To understand the overall dynamics of ultracold plasmas, one needs to understand Rydberg collisional processes at ultracold temperatures. The two kinds of problems addressed in this thesis are: study of Rydberg atomic processes at ultracold temperatures, and a study of the overall dynamics of the ultracold plasmas. Theoretical methods based on quantal-classical correspondence is used to understand Rydberg atomic processes such as radiative cascade, and radiative recombination. A simulation method suitable for ultracold collisions is developed and tested. This method is then applied to study collisional-Stark mixing in Rydberg atoms. To study the dynamics of the ultracold plasmas, a King model for the electrons in plasmas is proposed. The King model is a stationary, finite sized electron distribution for the electrons in a cloud of fixed ions with a Gaussian distribution. A Monte-Carlo method is developed to simulate the overall dynamics of the King distribution.

Thesis (D.Sc.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005? / "December 2004" Includes bibliographical references.

Thèse (D.Sc.)--Université du Québec à Chicoutimi, 1978. / Document électronique également accessible en format PDF. CaQCU

Low density plasmas are found throughout the known universe. Therefore, accurate diagnostic methods have implications for our understanding of a variety of topics, ranging from star formation to the semi conductor industry. Low density plasmas are ubiquitous in the material processing industry. However, measurements of the electron temperature and density, two of the most fundamental plasma properties, are not straightforward. In the laboratory, we create a low density, radio frequency, helium plasma with a bi-Maxwellian electron distribution, similar to those found in the semiconductor processing industry. We use optical emission spectroscopy to perform a non invasive measurement of the plasma conditions. We compare this to measurements obtained using a Langmuir probe, a commonly used invasive diagnostic. The optical emission spectroscopy is found to be insensitive to electron density but good agreement is found between the two techniques for values of the temperature of the hot electron component of the bi-Maxwellian. Plasmas created with high-intensity lasers are able to recreate conditions similar to those found during astrophysical events. This development has led to these condi- tions being explored in laboratories around the world. An experiment was performed at the Rutherford Appleton Laboratory in Didcot, UK, investigating the properties of supersonic turbulent jets. For the first time a magneto-optic probe was used to measure the magnetic field in a low-density supersonic turbulent plasma. The results were compared to measurements taken using a magnetic-induction probe. Good agreement was found between measurements of the magnetic field strength within the plasma; however, the magnetic power spectra differ. We attribute this to the dif- ference in integration length between the two measurements. Statistical properties of the velocity field are inferred from the magnetic field measurements, which compare favourably to astrophysical observations and hydrodynamic simulations.

Orientador: Edison Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-08T07:44:25Z (GMT). No. of bitstreams: 1 NascimentoNeto_EneasRamos_M.pdf: 883436 bytes, checksum: c17690c5dbef73787fd9632accf5eccc (MD5) Previous issue date: 2006 / Resumo: A crescente preocupação com o desenvolvimento sustentável aliado com uma maior conscientização com relação à preservação do meio ambiente tem impulsionado pesquisas nas mais diversas áreas de tecnologias ambientalmente corretas. Dentro deste contexto a tecnologia de plasma frio representa uma eficiente, ambientalmente correta e econômica alternativa para limpeza da superfície de alumínio. Este trabalho é a primeira etapa do projeto de modificação da superfície de alumínio coordenado pelo professor Edison Bittencourt. O projeto como um todo consiste de três etapas (limpeza, proteção e ativação) e tem a intenção de substituir via plasma o processo químico de limpeza, proteção à corrosão e ativação da superfície. Com relação à segunda etapa já foram realizados, no Instituto de Física pelo físico Carlos Salles Lambert, alguns ensaios de deposição de Hexametildisiloxano que mostraram ser excelentes protetores a corrosão, entretanto, essa segunda etapa não será discutida neste trabalho mas em posteriores teses. Neste trabalho realizou-se a remoção de óleo lubrificante e protetor da superfície de alumínio utilizando os gases oxigênio, hidrogênio, argônio e as misturas: oxigênio e argônio, hidrogênio e argônio. Foi analisada e discutida a influência da potência do gerador, tempo de bombardeamento, tipo de gás e pressão de trabalho sobre o ângulo de contato com água deionizada. A remoção do óleo lubrificante e protetor foi analisada em termos da medida do ângulo de contato de água deionizada e etileno glicol e da análise de XPS. Os experimentos foram realizados segundo técnica de planejamento experimental, em que as análises dos resultados experimentais foram realizadas através da Metodologia da Superfície de Resposta. A análise dos efeitos das variáveis sobre as variáveis de resposta do processo foi utilizada na construção de um modelo empírico, visando, a predição do comportamento do processo. A análise dos modelos obtidos foi realizada através da análise de variância (ANOVA). As variáveis independentes analisadas foram: potência do gerador, tempo de bombardeamento, tipo de gás e pressão de trabalho. Todas as variáveis operacionais foram analisadas em três diferentes níveis. Os resultados obtidos indicam que é possível remover o óleo lubrificante e protetor da superfície de alumínio utilizando o processo de plasma frio / Abstract: The increasing concern with the sustainable development ally with a bigger awareness with regard to the preservation of the environment has stimulated research in the most diverse areas of ambient correct technologies. Inside of this context the cold plasma technology represents an efficient, ambient correct and economic alternative for cleanness of the aluminum surface. It was analyzed and argued the influence of the power of the generator, sputtering time, type of gas and pressure of work on the angle of contact with water. This work is the first stage of the project of modification of the aluminum surface coordinated by professor Edison Bittencourt. The project as a whole consists of three stages (cleaning, protection and activation) and has the intention to substitute the chemical process of cleanness, protection the corrosion and activation of the surface for plasma process. With regard to second stage already they had been carried through, in the Institute of Physics for the physicist Carlos Salles Lambert, some assays of deposition of Hexametildisiloxano had shown to be excellent corrosion protectors, however, this second stage will not be argued in this work but in posterior works. In this work lubricative and protective oil was removed by gases such as oxygen, hydrogen, argon and the mixtures: oxygen and argon, hydrogen and argon. It was analyzed and argued the influence of the power of the generator, time of bombardment, type of gas and pressure of work on the angle of contact with water. The removal of the oil was analyzed in terms of the measure of the angle of contact with water and ethylene glycol and of the analysis of XPS.The experiments were carried out according experimental planning techniques where the obtained experimental results analyses had been carried through the Response Surface Methodology. The analysis of effect of the independent variable on the process answer variables had been used in the construction of an empirical model, aiming to predit the process behavior. The analysis of the obtained models was carried out using the variance analysis (ANOVA). The independent variable used had been: power of the generator, sputtering time, type of gas and pressure of work. The results obtained indicate that it is possible to remove the oil of the aluminum surface using the cold plasma process / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química