Evaluation of persistent-mode operation in a superconducting MgB2 coil in solid nitrogen
, Patel, D; Al Hossain, MS; See, KW; Qiu, WB ; Kobayashi, H; Ma, ZQ; Kim, SJ ; Hong, JG; Park, JY ; Choi, S; Maeda, M ; Shahabuddin, M ; Rindfleisch, M ; Tomsic, M; Dou, SX; Kim, JH . 2016
We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to obtain the persistent-current mode. After a heat treatment, the whole coil was installed in the SN2 chamber. During operation, the resultant total circuit resistance was estimated to be < 7.4 x 10(-14) Omega at 19.5 K +/- 1.5 K, which meets the technical requirement for magnetic resonance imaging application.
