Flux jumps in high-Jc MgB2 bulks during pulsed field magnetization. (2nd February 2016)

• Record Type: Journal Article
• Authors: Fujishiro, H; Mochizuki, H; Naito, T; Ainslie, M D; Giunchi, G
• Is Part Of: Superconductor science & technology. Volume 29:Number 3(2016:Mar.)
• Publication Date: 2016-02-02
• Subjects: flux jump -- MgB2 -- pulsed field magnetization -- numerical simulation -- critical thickness -- temperature rise; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/0953-2048/29/3/034006
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: Pulsed field magnetization (PFM) of a high- J c MgB2 bulk disk has been investigated at 20 K, in which flux jumps frequently occur for high pulsed fields. Using a numerical simulation of the PFM procedure, we estimated the time dependence of the local magnetic field and temperature during PFM. We analyzed the electromagnetic and thermal instability of the high- J c MgB2 bulk to avoid flux jumps using the time dependence of the critical thickness, d c ( t ), which shows the upper safety thickness to stabilize the superconductor magnetically, and the minimum propagation zone length, l m ( t ), to obtain dynamical stability. The values of d c ( t ) and l m ( t ) change along the thermally-stabilized direction with increasing temperature below the critical temperature, T c . However, the flux jump can be qualitatively understood by the local temperature, T ( t ), which exceeds T c in the bulk. Finally, possible solutions to avoid flux jumps in high- J c MgB2 bulks are discussed.