Influence of an AC magnetic field on a superconducting bulk magnetized in an iron core

Abstract : In order to design and understand some new electrical applications using superconducting permanent magnets, which have some very high trapped magnetic field, it is necessary to study their demagnetization. In a motor, for example, the magnets are submitted to an AC magnetic field. This could demagnetize the superconducting magnets which are themselves magnetized by a variable magnetic field. So in this article, we propose new experimentations in order to study the influence of an AC external magnetic field, including several amplitudes and frequencies, on a superconducting magnet. Our experiments are carried out in a liquid nitrogen bath, and we use YBCO superconducting bulk pellets. During the first step, we have magnetized a superconducting bulk in an iron core by a PFM method. The iron core represents the equivalent magnetic circuit of an electrical motor. For the first time, these experiments were carried out both directly after the bulk magnetization, and also some days after. The results comparison shows that the influence of alternative magnetic field is smaller in the second case when the magnetic field is applied after the stabilization of trapped field in the bulk. More important, we find also that the influence of an AC magnetic field is not repetitive. So for the superconducting motors and the magnetic coupling applications, and in order to obtain a stable superconducting magnet, it’s advised to apply the largest amplitude and the highest frequency of the expected magnetic field. This is an important result for the future potential applications referred.
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Contributor : Kévin Berger <>
Submitted on : Friday, September 11, 2015 - 1:04:42 PM
Last modification on : Thursday, January 18, 2018 - 3:06:05 PM

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Bashar Gony, Kévin Berger, Bruno Douine, Jean Lévêque. Influence of an AC magnetic field on a superconducting bulk magnetized in an iron core. EUCAS 2015 - 12th European Conference on Applied Superconductivity, Sep 2015, Lyon, France. p. 131, id. 2A-LS-P-03.05. ⟨hal-01197248⟩

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