SUPERCONDUCTIVITY

Author: PEREZ CABALLERO BELÉN M..
Year: 2003.
University: EXTREMADURA [www.unex.es].
Place of defense: ESCUELA DE INGENIERÍAS INDUSTRIALES.
Place of preparation: ESCUELA DE IGENIERIAS INDUSTRIALES.

Summary: The work aims to make a contribution to the field of transformdas supenconductores through the design, contrucción analysis anferentes prototype ham formed a core of iron, used as a constructive basis, equipment reperconductor in the form of tape. We implemented 2 transformdos, a toroidal and another rolenoidal with tape Bi-2223, are studied and measured their conficientes link, proposed the rectivos diaframas farociales and is lost in a study of the same.

Author: GONZALEZ JORGE HIGINIO.
Year: 2004.
University: VIGO [www.uvigo.es].
Place of defense: FACULTAD DE CIENCIAS DE OURENSE.
Place of preparation: FACULTAD DE CIENCIAS DE OURENSE.

Summary: In this dissertation shows various techniques for inducing flow persistent superconducting rings based on the use of a closed magnetic circuit so that, in comparison with the classical field cooling procedures, it decreases the size of the inductive coils and the current flowing through the mimas. In addition, the procedures shown in this work do not limit the size of the superconducting sample. Moreover, measures of flux creep in that the flow is induced by this method show that the flow caught in the rings superconductors is much lower than with traditional procedures and that there is independence between critical current ratio and relaxation. Moreover, this study measures flux creep for a period of time far superior to the times typically used for 10000 s, which observed a drop of regimén of Anderson-Kim after 20-30 hours from the beginning of the experience and then reaches a stabilization of the flow. There have also been separate, as far in a superconducting magnetic field, the component debitda the flow and due to the superconducting vortices, observámos the latter has contributed an order of magnitude smaller. In addition, there have been steps in shaping ferromagnetic superconductor ferromagnetic showing that a high density of trapped flux of ferromagnetic introduces a certain viscosity on the movement of vortices. Finally, we have also conducted studies on the superconducting ring configuration permanent magnet, showing an increase in the critical current when the trapped magnetic field in the superconductor is the opposite direction and the same magnitur that because of the magnet.

Author: SÁNCHEZ LOTERO PEDRO NEL.
Year: 2005.
University: ALICANTE [www.ua.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: UNIVERSIDAD DE ALICANTE.

Summary: In this Doctoral Thesis explores the network structure of vortices systems superfluidos. The states with minimizing the vortices are determined for each functional system, functional Ginzburg for superconductors and Gross-Pitaevskii for Bose-Einstein condensates. The systems being studied are superconducting strips and Bose-Einstein condensates very alargados.Las respective wave functions of each system are proposed as an expansion of autofunciones operator kinetic for superconductors and operators kinetic, and confinement for rotation condensates. The process of minimization is carried out by finding the corresponding coefficients of expansion that minimize each funcional.Para strips superconducting explores the effects of various types of interface in the network structure of vortices. Additionally explores critical areas expulsion of vortices when the magnetic field decreases trying to explain recent experimental results. Finally, it examines the impact of the flow in the network of vortices explaining, in light of the theory of Ginzburg, the nature of the critical current and the effect of the flow in the entry or exit of vortices in a tira.Para condensates very elongated explores the network of vortices for parabolic confinement and more of a parabolic wall infinite. Both are studying the structure of the network and are the type of phase transition that occurs when the system is a row of vortices by increasing the frequency of rotation