Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 201-208). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 201-208). Also available on the Internet.

Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009. / Committee Chair: M. R. Flannery; Committee Member: John Wood; Committee Member: Michael Schatz; Committee Member: Rigoberto Hernandez; Committee Member: Turgay Uzer. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 240-248). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 240-248). Also available on the Internet.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 114-120).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 126-130).

Orientador: Aruy Marotta / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-10T20:43:05Z (GMT). No. of bitstreams: 1 Bubliyeuski_DzmitryAlexandrovich_D.pdf: 2691341 bytes, checksum: 7b8e0d82f84d333a723eb14e64832cf3 (MD5) Previous issue date: 2008 / Resumo: Uma nova técnica de diagnóstico, denominada termo-espectroscópica, foi introduzida neste trabalho para estudo da interação do arco elétrico com o catodo frio de cobre numa instalação coaxial magnética, com catodo não-refrigerado, operando em gases plasmagênicos ar e nitrogênio. A técnica foi aplicada ao estudo da velocidade de rotação da mancha do arco e da densidade efetiva de corrente na mancha. Estes parâmetros têm estreita relação com o fenômeno da erosão de eletrodos frios. A nova técnica combina a técnica óptico-espectroscópica e a técnica térmica, e se baseia na teoria térmica da erosão. Por espectroscopia, registra-se a evolução temporal da intensidade da linha de emissão do vapor de cobre. Pelo método térmico, registra-se a evolução da temperatura da superfície do eletrodo. A técnica permite um grande aumento na sensibilidade de detecção do ponto de transição do regime de micro para macroerosão, através da observação do abrupto aumento da intensidade da linha espectral do cobre. Observamos que para o regime de microerosão, a velocidade é sempre maior, e a dispersão da velocidade sempre menor que na macroerosão. Esse fato confirma a existência de uma força de arraste superficial ao movimento do arco, que pode ser proporcionada pela fusão do eletrodo, por jatos catódicos e/ou por óxidos na superfície do eletrodo. A densidade de corrente na mancha apresenta um grande crescimento para valores baixos do campo magnético e certa saturação para altos valores. Para o ar foi observada uma forte influência dos óxidos na mobilidade da mancha, que é significativamente maior do que com nitrogênio. A diferença entre medidas obtidas no ar e nitrogênio é atribuída ao processo de decomposição de óxidos na superfície, que afeta a determinação correta do ponto de transição. O estudo experimental realizado nesta tese permite uma melhor compreensão dos fenômenos que ocorrem em manchas de arcos elétricos de eletrodos frios / Abstract: In the present work a new diagnostic technique, named thermo-spectroscopic one, was introduced for study of the interaction of the electric arc with a cold copper electrode using the coaxial magnetic installation with non-refrigerated cathode operated in air and nitrogen. The technique was applied to the measurement of the arc spot rotation velocity and the effective spot current density. These parameters have a direct relation with the phenomenon of the cold electrode erosion. The new technique combines the optic-spectroscopic method and the thermal method, and is based on the erosion thermophysical theory. Using spectroscopy, the temporal evolution of the intensity of the copper vapor emission line was registered. Via the thermal method, the evolution of the electrode surface temperature was recorded. By the observation of the abrupt increase of the copper spectral line intensity, the new technique permits a significative increase in the sensibility of the detection of the transition from the microerosion process to the macroerosion one. It was observed that the arc velocity for the microerosion regime is always higher and the velocity dispersion is always lesser then the ones for the macroerosion regime. This fact confirms the existence of the surface drag force to the arc movement, which can be provided by the electrode fusion process, by cathode jets and/or by oxides formed on the electrode surface. The arc spot current density presents a high growth for the low values of the magnetic field and certain saturation for the high values ones. For the air, a strong influence of oxides on the spot mobility was observed, that is more significant then the one for the nitrogen. The difference between the measurements for the air and the nitrogen is attributed to the oxide decomposition process on the electrode surface that affects the correct transition point determination. The experimental study, carried out in this thesis, allows a better understanding of the phenomenon taking place in cold electrode arc spots / Doutorado / Física de Plasmas e Descargas Elétricas / Doutor em Ciências

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.

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