MgB2 superconducting joints for persistent current operation

• Published in: Superconductor science & technology 2015-06, Vol.28 (6)
• Main Authors: Patel, Dipak, Al Hossain, Md Shahriar, Wai See, Khay, Xu, Xun, Barua, Shaon, Ma, Zongqing, Choi, Seyong, Tomsic, Mike, Ho Kim, Jung
• Format: Article
• Language: English
• Subjects: field-decay measurement; MgB; MRI application; peristent-mode magnets; superconducting joints; wire
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/28/6/065017

High-performance superconducting joints are essential for realizing persistent-mode magnets. Herein, we propose a concept and fabrication of such superconducting joints, which yielded reliable performance in the operating temperature range of 4.2-25 K. MgB2-MgB2 joints in magnets are known to result in deterioration of localized electrical, thermal, and mechanical properties. To overcome these problems, the ends of the two wires are inserted into a pellet press, which is then filled with a mixture of unreacted magnesium and boron powders, followed by heat treatment. The critical current capacity and joint resistance were precisely evaluated by the standard four-probe method in open-circuit and by field-decay measurements in a closed-loop, respectively. These joints demonstrated up to 66% of the current-carrying capacity of unjoined wire at 20 K, 2 T and joint resistance of 1.4 × 10−12 at 4.2 K in self-field.