No description available.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / Vita. / Includes bibliographical references. / Ph.D.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

No description available.

by M.A. Biondi and S.C. Brown. / "February 26, 1947." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039- sc-32037

Electron densities and collision frequencies were obtained on a number of gases in a dc discharge at low pressures (0.70-2mm of Hg). These measurements were performed by microwave probing of a filament of the dc discharge placed coaxially in a resonant cavity operating in a TM₀₁₀ mode. The equipment and techniques for making the microwave measurements employing the resonant cavity are described. One of the main features of this investigation is the technique of differentiating the resonance signal of the loaded cavity in order to make accurate measurements of the resonant frequency and half-power point frequencies.

This study describes the construction of a high vacuum station and the instrumentation and testing of two methods for obtaining the first derivative of the current-voltage characteristic of a Langmuir Probe, which is needed to determine the electron speed distribution in rare gases. The theory behind using a lock-in amplifier differentiator to obtain the derivative of the I-V characteristic of a Langmuir Probe is derived and discussed. A test was devised to check the instrumentation for correct operation. / M.S.

Orientador: Munemasa Machida / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-19T18:26:47Z (GMT). No. of bitstreams: 1 Ronchi_Gilson_M.pdf: 6202845 bytes, checksum: e9580b7846e57a9eb526cdf45b808564 (MD5) Previous issue date: 2012 / Resumo: O conhecimento das condições para ruptura de gases e a formação de plasma são questões importantes, não apenas de interesse fundamental, mas também para muitas aplicações, tais como em deposição de filmes finos de óxido ou polímeros, limpeza de superfície de materiais ou implantação iônica, por exemplo. A ruptura de gases descrita pela lei de Paschen com a teoria de Townsend, na qual a tensão de ruptura é uma função do produto da pressão p do gás pela distância d entre os eletrodos, proporciona uma adequada descrição em certas condições, em gases sob baixa pressão, quando a distância entre os eletrodos é muito menor que o raio R dos mesmos. A medida que a razão desses valores aumenta, as curvas de Paschen são deslocadas para regiões de tensão de ruptura mais elevadas, bem como para valores pd mais elevados. Investigamos aqui, os motivos e as consequências desse fenômeno, bem como uma proposta de lei de escalas capaz de determinar a tensão de ruptura em condições distintas de descargas. Tal lei de escalas obtida empiricamente faz uso, além da pressão e distância dos eletrodos, da razão R/d, que surge naturalmente ao se considerar o processo de difusão na descarga. Discutimos ainda sobre as principais técnicas de diagnósticos aplicáveis ao plasma, para obtenção, por exemplo, das temperaturas e densidades eletrônicas/iônicas. Em particular, revisamos as técnicas de espectroscopia e sonda de Langmuir, que são técnicas importantes amplamente utilizadas / Abstract: The understanding of the gas breakdown mechanism and plasma formation are important issues not only of fundamental interests, but also for many applications such as oxide thin films or polymers deposition, surface cleaning and ion implantation, for example. The breakdown described by Paschen¿s law with Townsend¿s theory, where the breakdown voltage is a function of the product of the gas pressure p and the gap distance d, provides a very accurate description under certain conditions as in low pressure gases when the distance between the electrodes is much smaller than its radius R. As the ratio d/R increases, the Paschen curves are shifted to regions of higher breakdown voltage, as well as higher pd values. In this work we investigate the reasons and consequences of this phenomenon, as well as a scaling law capable of determining the breakdown voltage of discharges in different conditions. This scalling law, obtained empirically, uses the gas pressure, the electrodes gap distance and the ratio R/d, which arises naturally when one consider the diffusion process in the discharge. We also discuss the main diagnostic techniques applicable to plasma to obtain, for example, temperature and electronic/ionic density. In particular, we review the techniques of spectroscopy and Langmuir probe, which are important techniques widely used / Mestrado / Física / Mestre em Física

Collective title supplied from typewritten manuscript of the thesis / Includes bibliographical references. / Incomplete (lacks pts. v-viii) / 15 items (14 items bound) : / Typescript, reprints / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Consists of a thesis (ms. typescript, hand written corrections) and reprints of collateral research papers submitted for the D.Sc. degree to the University of Adelaide by Brose / Thesis (D.Sc.)--University of Adelaide, 1931

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