Disputas: Sanyalak Niratisairak

M.Sc. Sanyalak Niratisairak ved Fysisk institutt vil forsvare sin avhandling for graden ph.d. (philosophiae doctor): Fluorescent thermal imaging of current-carrying high-Tc thin films

Prøveforelesning

Se prøveforelesning

Bedømmelseskomité

Professor Petriina Paturi, University of Turku, Finland
Ass. Prof. Michael R. Koblischka, University of Saarbrücken, Tyskland
Professor Knut Jørgen Måløy, Universitetet i Oslo, Norge

Leder av disputas:  Professor Alexander L. Read

Veileder:  Prof. Tom Henning Johansen and Prof. Michael Baziljevich

Sammendrag

Superledere er best kjent som tapsfrie elektriske ledere. Utnyttelse av denne overlegne elektriske egenskapen i elektroniske komponenter er tema for aktiv forskning. Forskningen byr ikke bare på ingeniørmessige utfordringer, men også superledernes mer fundamentale egenskaper er ikke fullt ut forstått. Når strømmen gjennom en superleder er større enn en gitt verdi, vil også superledere ha energitap i form av varme. Denne avhandlingen gir som resultat visualisering av varmetapet i tynne superledende filmer, som det går strøm igjennom. Dette bidrar til å øke forståelsen av superledere med redusert dimensjonalitet.

The superconductor is best known as a lossless electrical conducting media. Utilisation of such superior electrical property in electronic device is an ongoing research. It is not due to engineering challenges but the properties of superconductor are not fully understood. The energy loss, in a form of heat, can be found, when the transport current is higher than a certain value. The result of the thesis provided a visualisation of heat dissipation in a thin-film of superconductor, carrying transport currents. This provides a better understanding in research of a reduced dimension superconductor

When a structured thin-film superconductor transports excessive currents, a discontinuity of voltage respond can be found. The discontinuity can be caused by heat dissipation, which represents the energy loss, in the superconductor. In this thesis, the dissipation is observed by the fluorescent thermal imaging technique (FTI), which has been earlier developed at Advanced materials and complex system, department of Physics, the University of Oslo. Utilising FTI, the voltage discontinuity accompanying with heat dissipation can be identified. This provides a better understanding in research of a reduced dimension superconductor.

The principle of FTI is based on the fluorescence property of a chemical compound, called Europium(III) complex. The complex exhibits a fluorescent spectrum when it is exposed by the Ultraviolet light. The fluorescence intensity is lower as the temperature of the complex is higher. Utilising this temperature-dependence intensity, one can use the complex as a thermometer.

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Publisert 30. mars 2012 15:47 - Sist endret 13. apr. 2012 10:18