Investigation of flux jumps during pulsed field magnetization in graphene-added MgB2 bulks

Kazuya Yokoyama (1) , Tetsuo Oka (2) , Kévin Berger (3) , Rémi Dorget (3, 2) , Michael Rudolf Koblischka (2) , Mihai Alexandru Grigoroscuta (4) , Mihail Burdusel (4) , Dan Batalu (5) , Gheorghe Aldica (4) , Petre Badica (4) , Naomichi Sakai (2) , Muralidhar Miryala (2) , Masato Murakami (2)

1 Division of Electrical and Electronic Engineering
2 Department of Materials Science and Engineering
3 GREEN - Groupe de Recherche en Energie Electrique de Nancy
4 Laboratory of Magnetism and Superconductivity
5 Department of Materials Science and Physical Metallurgy

MgB2 bulk superconductors are expected to be utilized as rare-earth-free and lightweight trapped field magnets. However, the flux jumps frequently happen during the magnetizing processes, and heavily degrade the field-trapping performances. We have investigated the effect of additives to the MgB2 bulk samples prepared by spark plasma sintering process, and observed various flux jumps during the pulsed field magnetizing processes, which were carried out at 14 K which was obtained by the 2-stage GM cryocooler. The authors classified the flux motions as three categories as "no flux flow", "fast flux flow", and "flux jump" regions, and investigated the conditions where the flux jumps happen. We observed some drastic flux jumps in the pristine and clarified the effect of graphene addition to the flux jumps. The experimental results showed us a possible expansion of no flux jump region, and suggested us the improvement of field trapping capability.

Domaines: Electromagnétisme; Supraconductivité [cond-mat.supr-con]; Science des matériaux [cond-mat.mtrl-sci]; Energie électrique

Kazuya Yokoyama, Tetsuo Oka, Kévin Berger, Rémi Dorget, Michael Rudolf Koblischka, et al.. Investigation of flux jumps during pulsed field magnetization in graphene-added MgB2 bulks. Journal of Physics: Conference Series, 2020, 14th European Conference on Applied Superconductivity (EUCAS2019) 1-5 September 2019, Glasgow, UK, 1559, pp.012080. ⟨10.1088/1742-6596/1559/1/012080⟩. ⟨hal-02885701⟩