flux creep
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Author(s):  
Mike D Sumption ◽  
John Murphy ◽  
Timothy J Haugan ◽  
Milan Majoros ◽  
Danko C van der Laan ◽  
...  

Abstract We have measured ReBCO coated conductor-based CORC® and Roebel cables at 77 K in a Spinning Magnet Calorimeter which subjected the tapes in the samples to a radial magnetic field of 566 mT (peak) at frequencies up to 120 Hz (272 T/s, cyclic average) with an approximately sinusoidal waveform. The samples were oriented such that the field applied to the tapes within the cables was entirely radial, simplifying subsequent analysis. An expression for loss which included hysteretic, flux creep, and eddy current losses was fit to both the CORC® and the Roebel cables. This expression allowed easy comparison of the relative influence of eddy currents and flux creep (or power-law behavior) effects. The loss of both the CORC® and Roebel cables measured here were seen to be essentially the sum of the hysteretic loss, flux creep effects, and the normal metal eddy current losses of the individual tapes. The losses of these cables were measured at high B*dB/dt with no coupling current loss observed under the present preparation conditions. The influence of flux creep effects on loss were not negligible. The losses of the CORC® cable per meter of tape were seen to be reduced from the case of a flat tape because of the helical geometry of the tapes.


2021 ◽  
Vol 42 (1) ◽  
pp. 24-38
Author(s):  
MN Hasan ◽  
M Muralidhar

The pinning force density Fp and the critical current density Jc were investigated in Nd0.33Eu0.33Gd0.33Ba2Cu3O(NEG-123) superconductors with addition of NEG-211 and EG-211 secondary phase particles of the volume fractions up to 10 mol% by analyzing experimental data of DC magnetization and compared with theoretical calculation based on flux creep-flow model taking the pinning parameter into account. The pinning parameters such that the number of flux lines in the flux bundle (g2), the most probable value of pinning strength (Am), distribution width (σ2), upper critical field (Bc2) were determined so that a good fit was obtained between theoretical and experimental results. The Chittagong Univ. J. Sci. 42(1): 24-38, 2020


2020 ◽  
Vol 318 ◽  
pp. 113963
Author(s):  
N. Haberkorn ◽  
S. Suárez ◽  
S.L. Bud'ko ◽  
P.C. Canfield

2020 ◽  
Vol 33 (4) ◽  
pp. 044008
Author(s):  
M R Koblischka ◽  
S Pavan Kumar Naik ◽  
A Koblischka-Veneva ◽  
D Gokhfeld ◽  
M Murakami
Keyword(s):  

Author(s):  
Mikhael A. Vasyutin ◽  
Nikolay D. Kuzmichev ◽  
Dmitri A. Shilkin

The fractality effect of the normal phase clusters' boundaries of a high-temperature superconductor YBa2Cu3O7−x (YBCO) on the magnetic flux creep is investigated. Experimental current-voltage and magnetoresistive characteristics of YBCO at the boiling point of nitrogen are obtained. Based on the model of intergranular clusters with fractal boundaries, an approximation of the experimental data is obtained after geometric-probability analysis of the photomicrographs of the samples. A model of the magnetoresistive state caused by flux creep is proposed for various transport currents, and experimental and empirical dependences of the fractal dimension of the normal YBCO phase cluster boundaries on the constant magnetic field are found. The magnetic field intensity is determined for a given fractal dimension, at which the vortex penetration into the granules begins. It is shown that the state of the samples corresponds to the metastable phase of the vortex glass. The connectivity index of the stall paths of the vortex bundles at the percolation threshold is calculated.


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