arXiv subjects

Carles Navau

Publications and source records attributed to Carles Navau.

22 records · Page 2Linked to original sources

arXiv2002

Magnetic properties of superconducting multifilamentary tapes in perpendicular field. I: Model and vertical stacks

Current and field profiles, and magnetization and AC losses are calculated for an array of infinitely long superconducting tapes arranged vertically in a perpendicularly applied magnetic field. Calculations are based on the critical state model. The finite thickness of the tapes and the effects of demagnetizing fields are considered. The influence of the magnetic coupling of the filaments in the magnetic properties of the arrays are studied. The general model can be applied to an arbitrary arrangement of tapes as long as there is reflection symmetry with respect to the vertical central plane.

cond-mat.supr-con↗

arXiv2002

Magnetic properties of superconducting multifilamentary tapes in perpendicular field. II: Horizontal and matrix arrays

Current and field profiles, and magnetization and ac losses are calculated for arrays of infinitely long superconducting tapes in the critical state in a perpendicularly applied magnetic field. The tapes are arranged both horizontally and in a matrix configuration, which is the geometry found in many actual high-T_c superconducting tapes. The finite thickness of the tapes and the effects of demagnetizing fields are considered. Systematic results for the magnetization and ac losses of the tapes are obtained as function of the geometry and separation of the constituent tapes. Results allow to understand some unexplained features observed in experiments, as well as to propose some future directions.

cond-mat.supr-con↗

arXiv2002

Stiffness and energy losses in cylindrically symmetric superconductor levitating systems

Stiffness and hysteretic energy losses are calculated for a magnetically levitating system composed of a type-II superconductor and a permanent magnet when a small vibration is produced in the system. We consider a cylindrically symmetric configuration with only vertical movements and calculate the current profiles under the assumption of the critical state model. The calculations, based on magnetic energy minimization, take into account the demagnetization fields inside the superconductor and the actual shape of the applied field. The dependence of stiffness and hysteretic energy losses upon the different important parameters of the system such as the superconductor aspect ratio, the relative size of the superconductor-permanent magnet, and the critical current of the superconductor are all systematically studied. Finally, in view of the results, we provide some trends on how a system such as the one studied here could be designed in order to optimize both the stiffness and the hysteretic losses.

cond-mat.supr-con↗

arXiv2001

Critical-current density from magnetization loops of finite high-Tc superconductors

We analyze the effects of demagnetizing fields in the magnetization hysteresis loops of type-II superconductors, by a model that allows the calculation of current and field profiles in finite cylindrically symmetric superconductors in the critical state. We show how the maximum in the magnetization curve gradually shifts from negative applied field values to the central position with decreasing sample thickness. From the analysis of the calculated field profiles, we demonstrate that one can obtain the intrinsic field-dependent critical-current density of the superconductor with great accuracy by measuring the magnetic response of superconductors with large aspect ratio with the applied field parallel to the shortest dimension.

cond-mat.supr-con↗