Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Superconductivity: Properties and Electronic Structure
TT 6.10: Vortrag
Montag, 7. März 2016, 12:30–12:45, H19
Trapped field measurements on MgB2 bulk samples — Michael Koblischka1, •Thomas Karwoth1, XianLin Zeng1, Kévin Berger2, Bruno Douine2, and Uwe Hartmann1 — 1Institute of Experimental Physics, Saarland University, P. O. Box 151150, D-66041 Saarbrücken, Germany — 2University of Lorraine, GREEN, 54506 Vandoeuvre-lès-Nancy, France
Trapped field measurements were performed on bulk, polycrystalline MgB2 samples stemming from different sources with the emphasis to develop applications like superconducting permanent magnets (’supermagnets’) and electric motors. We describe the setup for the trapped field measurements and the experimental procedure (field cooling, zero-field cooling, field sweep rates). The trapped field measurements were conducted using a cryocooling system to cool the bulk samples to the desired temperatures, and a low-loss cryostat equipped with a room-temperature bore and a maximum field of ±5 T was employed to provide the external magnetic field. The superconducting coil of this cryostat is operated using a bidirectional power supply. Various sweep rates of the external magnetic field ranging between 1 mT/s and 40 mT/s were used to generate the applied field. The measurements were performed with one sample and two samples stacked together. A maximum trapped field of 7 T was recorded. We discuss the results obtained and the problems arising due to flux jumping, which is often seen for the MgB2 samples cooled to temperatures below 10 K.