Estudo do plasma produzido por descarga elétrica no limiar da transição townsend - "glow"

• Ano de defesa: 2007
• Autor(a) principal: Farias, Eliel Eleuterio
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Programa de Pós-graduação em Física; Física
• Palavras-chave em Português: Plasma (Física); Magnetoidrodinâmica; Plasma; Circuito; Amplificação de sinal; Descarga; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://app.uff.br/riuff/handle/1/18945

In this master thesis we present results from a study of plasma produced by electrical discharges in a neon lamp. Some phenomena of non linear nature are analyzed and registered, in which we emphasize the self oscillation phenomenon. In the analysis performed, the characteristic voltage versus current of the lamp play a decisive role for the elucidation of the phenomenon. In the theoretical analysis we have used a combined descrition of plasma where we use Circuit Equations and MHD theory to get the connection between the circuit elements and the plasma MHD parameters. The perfect understanding of the physical mechanism that produces the self oscillation phenomenon opens doors for technological applications of plasmas produced by electrical discharges as an electronic device. The study made here can be considered as a start point to a new research line about plasma production by discharges and electronic devices. Previous papers related to non linear phenomena in plasmas cited here were limited to a phenomenological description some experimental results and the use of non linear mathematics. Little or nothing was disclosed about the physical nature of the phenomena. In this work we were able to associate the self oscillation phenomenon with plasma production in the threshold region of transition between Townsend and glow discharge. We propose two innovative theoretical approaches. The first one is to describe the laboratory plasma through resistive elements RP and/or reactive ÂP of the circuit in connection with the complex Poynting theorem. The output of this approach gives analytical expressions for RP and ÂP as a function of plasma and geometric discharge parameters, that may be used as a guide to perform changes in the discharge chamber in such way to obtain more adequated values of the plasma resistance and reactance. The second approach uses circuit theory to describe the plasma being represented by a parallel RC circuit and in the which, the process of plasma self oscillation is induced by a spontaneous transition between the regimes of Townsend and glow discharge.