Critical-current density of melt-grown single-grain Y–Ba–Cu–O disks determined by ac susceptibility measurements

Chen, D.-X.; Sanchez, Alvaro; Navau, Carles; Shi, Yunhua; Cardwell, D. A.

doi:10.1088/0953-2048/21/8/085013

Cited by 15 publications

(21 citation statements)

References 34 publications

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“…The maximum values of the normalised losses given by the 2-D model (0.0630) are slightly low compared to the 1-D prediction (0.0657). Note that the full-penetration field H p for the long sample (2-D) is slightly smaller (98.2%) than that for the infinite cylinder, as can be calculated from the analytical expression for a finite cylinder [48]. However, the modeling is always carried out for field amplitude H m = ½ H p .…”

Section: Distribution Of Ac Losses At a Constant Temperature -Modelingmentioning

confidence: 99%

Self-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field

Laurent¹,

Fagnard²,

Babu³

et al. 2010

Supercond. Sci. Technol.

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Abstract. In this work we study, both experimentally and numerically, the self-heating of a bulk, large YBCO pellet of aspect ratio (thickness / diameter) ~ 0.4 subjected to a large AC magnetic field. To ensure accurate temperature measurements, the sample was placed in an experimental vacuum chamber to achieve a small and reproducible heat transfer coefficient between the superconductor and the cryogenic fluid. The temperature was measured at several locations on the sample surface during the self-heating process. The experimentally determined temperature gradients are found to be very small in this arrangement (< 0.2 K across the radius of the superconductor). The time-dependence of the average temperature T(t) is found to agree well with a theoretical prediction based on the one-dimensional (1-D) Bean model, assuming a uniform temperature in the sample. A 2-D magneto-thermal model was also used to determine the space and time-dependent temperature distribution T (r, z, t) during the application of the AC field. The losses in the bulk pellet were determined using an algorithm based on the numerical method of Brandt, which was combined with a heat diffusion algorithm implemented using a finite-difference method. The model is shown to be able to reproduce the main trends of the observed temperature evolution of the bulk sample during a self-heating process. Finally, the 2-D model is used to study the effect of a non-uniform distribution of critical current density J c (r, z) on the losses within the bulk superconductor.

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Section: Distribution Of Ac Losses At a Constant Temperature -Modelingmentioning

confidence: 99%

Self-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field

Laurent¹,

Fagnard²,

Babu³

et al. 2010

Supercond. Sci. Technol.

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“…Another way of determining the exponent from measurements is to use scaling laws [1], [2], [10], [17]. The AC susceptibility [17] and hence the shielding factor SF measured for several combinations of , and should be a factor of a single variable .…”

Section: B Flux Creep Effects and Determination Ofmentioning

confidence: 99%

“…The AC susceptibility [17] and hence the shielding factor SF measured for several combinations of , and should be a factor of a single variable . On Fig.…”

Section: B Flux Creep Effects and Determination Ofmentioning

confidence: 99%

DC and AC Shielding Properties of Bulk High-Tc Superconducting Tubes

Fagnard

Denis

Lousberg

et al. 2009

IEEE Trans. Appl. Supercond.

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Abstract-We have studied numerically and experimentally the magnetic flux penetration in highsuperconducting tube subjected to a uniform magnetic field parallel to its long axis. This study is carried in view of designing low-frequency magnetic shields by exploiting the diamagnetic properties of high-superconducting ceramics. We have measured the field attenuation for applied magnetic fields in the frequency range 5 mHz-0.1 Hz by Hall probe measurements and at audio frequencies using a sensing coil. A simple 1D analysis using the Kim critical state model was found to be able to reproduce the experimental data satisfactorily. We have also determined the phase shift between the internal and the applied field both experimentally and numerically. Finally, we have studied the sweep rate dependence of the magnetic shielding properties, using data recorded either at several constant sweep rates d d or at several AC fields of various amplitudes and frequencies. Both methods agree with each other and lead to a -value of the n law equal to 40 at 77 K.

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“…In the CSM, the current density J can only be equals to 0 or the critical current density JC independent of the rate of variation of the externally applied magnetic field. Thanks to CSM, JC can be simply determined by experiments [9]- [10].…”

Section: Introductionmentioning

confidence: 99%

Determination of the Complete Penetration Magnetic Field of a HTS Pellet From the Measurements of the Magnetic Field at Its Top-Center Surface

Douine

Berger

Trillaud

et al. 2018

IEEE Trans. Appl. Supercond.

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Abstract-In previous papers a new method to characterize HTS pellets has been presented This method is based on the measurement of their complete penetration magnetic flux density BP. It allows determining the critical current density JC and the nvalue of the classical power law model. In this paper, a method of determination of BP of a unique HTS pellet from the measurements of the magnetic field at its top-center surface is presented. This is a simpler and cheaper method than previous methods. It uses analytical calculation based on Biot and Savard law and numerical calculation based on power law. The maximum magnetic flux density produced by the SC pellet BZSCM is deduced from the measurement. BP is deduced from BZSCM multiplying it by a coefficient analytically calculated. The influence of JC(B) on this method is presented and analyzed.  Index Terms-Superconductors, magnetic field diffusion, critical current density.

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Critical-current density of melt-grown single-grain Y–Ba–Cu–O disks determined by ac susceptibility measurements

Cited by 15 publications

References 34 publications

Self-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field

Self-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field

DC and AC Shielding Properties of Bulk High-Tc Superconducting Tubes

Determination of the Complete Penetration Magnetic Field of a HTS Pellet From the Measurements of the Magnetic Field at Its Top-Center Surface

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