Experimental Research of the New Developed High-Jc Nb3Sn Superconducting Strand for 14 T MRI Magnet

The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) has announced a project to design and manufacture a high field MRI magnet with a 900 mm warm bore and comprised of Nb
₃
Sn Rutherford cables in 2017. The maximum magnetic induction of magnet system is 14.3 T and magnetic field homogeneity in a spherical volume with 22 cm diameter is better than 0.5 ppm. The high performance Nb
₃
Sn strand is the potential options to use for such high field magnet system. ASIPP cooperates with Western Superconducting Technologies Company (WST) to develop high performance Nb
₃
Sn strand whose critical current density J
_c
is higher than 2000 A/mm
²
at 4.2 K, 12 T. To obtain the actual performance of WST high performance Nb
₃
Sn strand, three short samples are prepared with different non-copper ratio or different heat treatment, the critical current I
_c
or quench current of all sample is measured at different field by the voltage-current (V-I) method, the residual resistivity ratio (RRR) of all sample is also measured. To study the strand whether it will be affected by low field instability, a small coil is built with WST strand, and the experimental result is presented and discussed in this paper.