Erratum: Critical current density from magnetization hysteresis data using the critical-state model [Phys. Rev. B64, 014508 (2001)]

The temperature and amplitude of AC field dependencies of both inter-and intragranular T p and T g temperatures of the imaginary peaks of χ′′ has been studied for a sintered single phase (Bi,Pb):2223 superconductor. The AC field dependencies for T p and T g and the relation between inter- and intragrain force densities were discussed by using Müller critical-state model. From the χ′′(T) curve, the values of intergrain magnetic critical current density J cJ was obtained via the application of Bean's critical state model. J cJ (T) dependence near T c agree with the assumption of SNS intergrain junctions.

Download Full-text

The Fe Influence on the Vortex Response to the AC Field in Bulk (Bi, Pb):2223 Superconductor

Modern Physics Letters B ◽

10.1142/s021798499800130x ◽

1998 ◽

Vol 12 (27) ◽

pp. 1117-1124 ◽

Cited By ~ 1

Author(s):

A. V. Pop

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Critical State ◽

Ac Susceptibility ◽

Field Amplitude ◽

Critical State Model ◽

Pinning Force ◽

Fast Decrease ◽

Ac Field

The effect of Fe 3+ ions on the inter- and intragranular Tp and Tg temperatures of the imaginary peaks of the AC susceptibility has been studied for a (Bi, Pb):2223 superconductor. The linear dependencies of Tp and Tg as a function of AC field amplitude agree with Muller critical state model. The Fe 3+ ions induced a fast decrease of inter and intragranular pinning force densities. The intergrain critical current density J cj calculated from χ″(T) curve is lower in x=0.02 Fe doped sample than in x=0.00 sample. J cj (T) dependence near Tc agrees with the assumption of SNS intergrain junctions.

Download Full-text

How to Choose the Superconducting Material Law for the Modelling of 2G-HTS Coils

Materials ◽

10.3390/ma12172679 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2679 ◽

Cited By ~ 2

Author(s):

Bright Chimezie Robert ◽

Muhammad Umar Fareed ◽

Harold Steven Ruiz

Keyword(s):

Magnetic Field ◽

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Critical State ◽

Homogeneous Distribution ◽

Angular Anisotropy ◽

Superconducting Tape ◽

Superconducting Material ◽

Superconducting Coil

In an attempt to unveil the impact of the material law selection on the numerical modelling and analysis of the electromagnetic properties of superconducting coils, in this paper we compare the four most common approaches to the E-J power laws that serve as a modelling tool for the conductivity properties of the second generation of high-temperature superconducting (2G-HTS) tapes. The material laws considered are: (i) the celebrated E-J critical-state like-model, with constant critical current density and no dependence with the magnetic field; (ii) the classical Kim’s model which introduces an isotropic dependence with the environment magnetic field; (iii) a semi-empirical Kim-like model with an orthonormal field dependence, J c ( B ) , widely used for the modelling of HTS thin films; and (iv) the experimentally measured E–J material law for SuperPower Inc. 2G-HTS tapes, which account for the magneto-angular anisotropy of the in-field critical current density J c ( B ; θ ) , with a derived function similar to Kim’s model but taking into account some microstructural parameters, such as the electron mass anisotropy ratio ( γ ) of the superconducting layer. Particular attention has been given to those physical quantities which within a macroscopic approach can be measured by well-established experimental setups, such as the measurement of the critical current density for each of the turns of the superconducting coil, the resulting distribution of magnetic field, and the curve of hysteretic losses for different amplitudes of an applied alternating transport current at self-field conditions. We demonstrate that although all these superconducting material laws are equally valid from a purely qualitative perspective, the critical state-like model is incapable of predicting the local variation of the critical current density across each of the turns of the superconducting coil, or its non-homogeneous distribution along the width of the superconducting tape. However, depending on the physical quantity of interest and the error tolerance allowed between the numerical predictions and the experimental measurements, in this paper decision criteria are established for different regimes of the applied current, where the suitability of one or another model could be ensured, regardless of whether the actual magneto angular anisotropy properties of the superconducting tape are known.

Download Full-text