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Stability and bifurcations of modes of current transfer to cathodes of DC gas discharges

2011Doctoral thesis Restricted access
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datacite.subject.fosCiências Naturais::Ciências Físicaspt_PT
dc.contributor.advisorBenilov, Mikhail
dc.contributor.authorFaria, Maria José Gomes
dc.date.accessioned2017-03-08T10:21:18Z
dc.date.available2017-03-08T10:21:18Z
dc.date.issued2011
dc.description.abstractStability of di⁄erent steady-state modes of current transfer to cathodes of DC highpressure arcs and of di⁄erent axially symmetric modes of current transfer of DC glow discharges against small perturbations is investigated in the framework of the linear stability theory. The eigenvalue problem for perturbations is solved with the use of software COMSOL Multiphysics. For the arc discharge, it was found that only the di⁄use mode and the rst 3D spot mode can be stable. The transition between the two modes is non-stationary and accompanied by hysteresis. For the glow discharge, variations of the increments of perturbations with discharge current are investigated for the 1D glow discharge and di⁄erent modes of axially symmetric glow discharge. Both real and complex increments have been detected, meaning that perturbations can vary with time both monotonically and with oscillations. In general, results given by the linear stability theory conrm intuitive concepts developed in the literature and conform to the experiment. On the other hand, the theory provides suggestions for further experimental and theoretical work. Bifurcations encountered in numerical modelling of current transfer to cathodes of DC high-pressure arcs and of DC glow discharges are analyzed. All basic types of steady-state bifurcations (fold, transcritical, pitchfork) have been identied and analyzed. The analysis provides explanations to many results obtained in numerical modelling. In particular, it is shown that dramatic changes of patterns of current transfer to cathodes of both glow and arc discharges, described by numerical modelling, occur through perturbed transcritical bifurcations of rst and second order contact. For the case of the arc discharge, e⁄ect over stability of cathode geometry and temperature of cooling was studied. It was found that changes of patterns of the steady-state modes occur due to interplay of self-organization and geometric factors.pt_PT
dc.description.abstractA estabilidade de diferentes modos estacionÆrios de transferŒncia de corrente para cÆtodos de arco a alta pressªo e de diferentes modos estacionÆrios axialmente simØtricos de transferŒncia de corrente em descargas luminescentes em relaªo a pequenas perturbaıes Ø investigada no mbito da teoria da estabilidade linear. O problema de valores prprios para as perturbaıes Ø resolvido atravØs do software COMSOL Multiphysics. Na descarga de arco, vericou-se que apenas o modo difuso e o primeiro modo mancha 3D podem ser estÆveis. A transiªo entre os dois modos Ø nªo-estacionÆria e acompanhada por histerese. Na descarga luminescente, as variaıes dos incrementos das perturbaıes com a corrente sªo investigadas para o caso 1De para diferentes modos axialmente simØtricos. Incrementos reais e complexos foram detectados, o que signica que as perturbaıes podem variar com o tempo tanto monotonicamente como com oscilaıes. Em geral, os resultados fornecidos pela teoria da estabilidade linear conrmam os conceitos intuitivos desenvolvidos na literatura e estªo em conformidade com as experiŒncias. A teoria tambØm fornece sugestıes para trabalhos tericos e experimentais. As bifurcaıes encontradas durante a modulaªo numØrica da transferŒncia de corrente para os cÆtodos de arco a alta pressªo e em descargas luminescentes sªo analisadas. Todos os tipos bÆsicos de bifurcaıes estacionÆrias foram identicados e analisados. A anÆlise fornece explicaıes para muitos dos resultados obtidos na modulaªo numØrica. Em particular, Ø mostrado que mudanas dramÆticas dos padrıes de transferŒncia de corrente para ambos os cÆtodos das descargas luminescente e de arco ocorrem por meio de perturbaıes de bifurcaıes transcrticas de contato de primeira e segunda ordem. No caso da descarga de arco, o efeito da geometria do cÆtodo e da temperatura de arrefecimento sobre a estabilidade foi estudado. Vericou-se que as mudanas dos padrıes dos modos estacionÆrios ocorrem devido a uma interaªo entre auto-organizaªo e fatores geomØtricos.pt_PT
dc.identifier.tid101258755pt_PT
dc.identifier.urihttp://hdl.handle.net/10400.13/1441
dc.language.isoengpt_PT
dc.relationESTUDO DA ESTABILIDADE DE TRANSFERÊNCIA DE CORRENTE AOS ELÉCTRODOS NAS DESCARGAS DE GÁS
dc.relationModes of current transfer to cathodes of high-pressure arc discharges and their stability
dc.relationCathode spots in high-pressure DC gas discharges: self-organization phenomena
dc.relationTheory and modelling of plasma-cathode interaction in high-pressure arc discharges
dc.subjectHigh-pressure arc dischargept_PT
dc.subjectGlow dischargept_PT
dc.subjectCathode spotspt_PT
dc.subjectSelf-organizationpt_PT
dc.subjectStabilitypt_PT
dc.subjectBifurcationspt_PT
dc.subjectDescarga de arco a alta pressãopt_PT
dc.subjectDescarga luminescentept_PT
dc.subjectManchas catódicaspt_PT
dc.subjectAuto-organizaçãopt_PT
dc.subjectEstabilidadept_PT
dc.subjectBifurcaçõespt_PT
dc.subjectFísicapt_PT
dc.subject.pt_PT
dc.subjectFaculdade de Ciências Exatas e da Engenharia
dc.titleStability and bifurcations of modes of current transfer to cathodes of DC gas dischargespt_PT
dc.typedoctoral thesis
dspace.entity.typePublication
oaire.awardTitleESTUDO DA ESTABILIDADE DE TRANSFERÊNCIA DE CORRENTE AOS ELÉCTRODOS NAS DESCARGAS DE GÁS
oaire.awardTitleModes of current transfer to cathodes of high-pressure arc discharges and their stability
oaire.awardTitleCathode spots in high-pressure DC gas discharges: self-organization phenomena
oaire.awardTitleTheory and modelling of plasma-cathode interaction in high-pressure arc discharges
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/PIDDAC/SFRH%2FBD%2F35883%2F2007/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/POCI/POCI%2FFIS%2F60526%2F2004/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FFIS%2F68609%2F2006/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/POCI/POCTI%2FFIS%2F32411%2F2000/PT
oaire.fundingStreamPIDDAC
oaire.fundingStreamPOCI
oaire.fundingStream3599-PPCDT
oaire.fundingStreamPOCI
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsclosedAccesspt_PT
rcaap.typedoctoralThesispt_PT
relation.isProjectOfPublicationdf662e2d-1a8f-459b-94ca-d09101967c7e
relation.isProjectOfPublication644330bd-ba62-4b15-a65a-d8b85244e455
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relation.isProjectOfPublication.latestForDiscovery0c0f344b-25a8-4e62-b2ee-bdc0e632c6a5
thesis.degree.nameDoutoramento em Físicapt_PT

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