Influence of the physical parameters on the limits of magnetic stiffness of high-Tc superconducting levitation systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 221-227
Author(s):  
Xianfeng Zhao ◽  
Zhiqi Zhou ◽  
Yuan Liu ◽  
Luquan Yang
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Applied Magnetic Field ◽  
Physical Parameters ◽  
High Temperature Superconducting ◽  
Magnetic Stiffness ◽  
Superconducting Levitation

Magnetic stiffness is one of the important stability parameters of high temperature superconducting levitation systems. Till to now, great efforts have been made to understand levitation properties including flux penetration, magnetization curves, levitation force, ac susceptibilities, etc. In this paper we present a quadratic approximation method for the limit of magnetic stiffness in a high temperature superconducting levitation system based on Kim’s critical state model and Ampère law. The system is composed with a cylindrical permanent magnet (PM) and a coaxial high temperature superconductor (HTS). It is found that the limit of magnetic stiffness depends upon both the penetration history of shielding currents distribution in HTS and applied magnetic field gradients. Furthermore, the influence of the physical parameters, such as critical current density in HTS and applied magnetic field, on the limits of magnetic stiffness is investigated in detail. The obtained results display that magnetic stiffness decreases with the increasing of critical current density, since shielding currents have not penetrated into the large portion of the HTS. With the increase of applied magnetic field, the magnetic stiffness obtain a larger magnification factor. It is related to the increase of the shielding current penetration volume and the internal magnetic field in HTS.

scholarly journals Increase in Critical Current Density for Increasing Applied Magnetic Field in a High-Temperature Superconducting Superlattice

2018 ◽  
Author(s):  
Shinichi Ishiguri ◽  
Shotaro Tawara
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Applied Magnetic Field ◽  
Stationary Wave ◽  
Superconducting Layer ◽  
High Temperature Superconducting ◽  
Insulator Layers

In the present work, a superlattice structure comprising superconducting and insulator layers is studied. Here, if a magnetic field is applied parallel to the layers, the lack of a pinning center leads to a novel transition; in particular, as the applied magnetic field is reduced, the stationary wave surrounding the magnetic flux quantum in the superconducting layer eventually collides with the superconducting–insulating interfaces on both sides because its radius becomes larger than the width of the superconducting layer. At this instant, the stationary wave will collapse, and a transition will occur: the magnetic quanta are collapsed and thus the uniform magnetic field distribution is achieved, which corresponds to the transition from the superconducting state to the normal state over critical current. Considering a one-dimensional model of the structure, a critical current density equation is derived that indicates an increase in the critical current density for increased applied magnetic field. Subsequently, the same calculation was conducted after changing the direction of the magnetic field component, and the combination of these two calculations expresses the anisotropic property of the structure. The phenomenon is also predicted for anisotropic critical current density. This phenomenon is an important discovery that helps manufacture high-temperature superconducting tape as well as large high-temperature superconducting coils.

ENHANCEMENT OF TRANSPORT CRITICAL CURRENT DENSITY IN NANO Cr2O3 ADDED Ag-SHEATHED (Bi1.6Pb0.4)Sr2Ca2Cu3O10 SUPERCONDUCTOR TAPES

2010 ◽  
Vol 24 (28) ◽  
pp. 5625-5634
Author(s):  
W. KONG ◽  
R. ABD-SHUKOR
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Applied Magnetic Field ◽  
Applied Field ◽  
Transport Critical Current Density ◽  
Force Density ◽  
Pinning Force ◽  
Ray Patterns

Ag -sheathed ( Bi 1.6 Pb 0.4) Sr 2 Ca 2 Cu 3 O 10( Bi –2223) high temperature superconductor tapes with 0.1 wt% nano Cr 2 O 3 were fabricated using the powder-in-tube method. The effects of intermediate rolling and sintering temperature on the transport critical current density (Jc) under self-field and applied magnetic field were studied. The X-ray patterns showed a dominant Bi –2223 phase (~80%). A decrease in Jc in applied magnetic field, parallel or perpendicular to the sample wide surface was observed for all tapes. Intermediate rolling improved the self-field Jc(T=77 K ) of the tapes by 25%. Both Jc versus applied field curves and normalized pinning force density Fp/Fp max versus applied field curves showed that the pinning strength was significantly enhanced with thermo-mechanical treatments. SEM micrographs showed improvements in the grain alignment of tapes with intermediate rolling. Enhancement in Jc was observed in the nano Cr 2 O 3 added tapes.

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