Superconductors are key materials for shielding quasi-static magneticfields. In this work, we investigated the shielding properties of an MgB2 cup-shaped shield with small aspect-ratio of height/outer radius. Shape and aspect-ratio were chosen in order to address practical requirements of both high shielding factors (SFs) and space-saving solutions. To obtain large critical current densities (Jc), which are crucial for achieving high magnetic-mitigation performance, a high-purity starting MgB2 powder was selected. Then, processing of the starting MgB2 powder into high density bulks was performed by spark plasma sintering. The as-obtained material is fullymachinable and was shaped into a cup-shield. Assessment of the material by scaling of the pinning force showed a non-trivial pinning behaviour. The MgB2 powder selection was decisive in enlarging the range of external fields where efficient shielding occurs. The shield’s properties were measured in both axial- and transverse-field configurations using Hall probes. Despite a height/outer radius aspect ratio of 2.2, shielding factors higher than 10^4 at T = 20 K up to a threshold field of 1.8 T were measured in axial-field geometry at a distance of 1 mm from the closed extremity of the cup, while SFs > 10^2 occurred in the inner half of the cup. As expected, this threshold field decreased with increased temperature, but SFs still exceeding the above mentioned values were found up to 0.35 T at 35 K. The shield’s shape limits the SF values achievable in transverse-field configuration. Nevertheless, the in-field Jc of the sample supported SFs over 40 at T = 20 K up to a field of 0.8 T, 1 mm away from the cup closure.
High magnetic shielding properties of an MgB2 cup obtained by machining a spark-plasma-sintered bulk cylinder / Gozzelino, Laura; Gerbaldo, Roberto; Ghigo, Gianluca; Torsello, Daniele; Bonino, Valentina; Truccato, Marco; Grigoroscuta, Mihai A; Burdusel, Mihail; Aldica, Gheorghe V; Sandu, Viorel; Pasuk, Iuliana; Badica, Petre. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - STAMPA. - 33:4(2020), p. 044018.
|Titolo:||High magnetic shielding properties of an MgB2 cup obtained by machining a spark-plasma-sintered bulk cylinder|
|Data di pubblicazione:||2020|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1088/1361-6668/ab7846|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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