Close circuit test of MgB₂coil with superconducting joints and a persistent current switch

Magneto-optical imaging of superconducting MgB2joints

“…A main reason for this effort is the development of cryogen-free MgB 2 coils for magnetic resonance imaging (MRI) [1][2][3][4][5][6]. Although different designs of MRI systems were considered based on the use of cryocoolers [1], conduction cooling systems [2,5] or solid nitrogen [3,4], all of them benefited from the relatively high critical temperature of MgB 2 and its high performance at a modest price of production. The first MRI models with MgB 2 coils [1,2] did not use superconducting joints, but it became clear that such joints would significantly improve their performance.…”

“…The first MRI models with MgB 2 coils [1,2] did not use superconducting joints, but it became clear that such joints would significantly improve their performance. Since then, several types of superconducting joints for connection of mono-and multifilamentary MgB 2 wires have been developed and tested [2][3][4][5][7][8][9][10].…”

“…Both sintered and non-sintered wires have been used, with better results achieved for the non-sintered wires. Another method [5] used a smaller contact area in the wire-in-wire design. A high pressure was applied to the joint followed by sintering.…”

“…The simplicity of preparing bulk MgB 2 , its low mass density and the availability of raw materials could make it a major driving force of a future liquid hydrogen economy. The progress in MgB 2 joint design and fabrication [2][3][4][5][7][8][9][10] gives good reasons for optimism.…”

“…Traditional methods for testing of joints are based on transport [2,4,[8][9][10][11] and current-decay [2,4,5,7,8,10] measurements. This paper focuses on alternative testing methods using magneto-optical imaging (MOI) and magnetization measurements.…”