  Magnetic field of up to 12 T was applied during the sintering process of pure
MgB2 and carbon nanotube (CNT) doped MgB2 wires. We have demonstrated that
magnetic field processing results in grain refinement, homogeneity and
significant enhancement in Jc(H) and Hirr. The Jc of pure MgB2 wire increased
by up to a factor of 3 to 4 and CNT doped MgB2 by up to an order of magnitude
in high field region respectively, compared to that of the non-field processed
samples. Hirr for CNT doped sample reached 7.7 T at 20 K. Magnetic field
processing reduces the resistivity in CNT doped MgB2, straightens the entangled
CNT and improves the adherence between CNTs and MgB2 matrix. No crystalline
alignment of MgB2 was observed. This method can be easily scalable for a
continuous production and represents a new milestone in the development of MgB2
superconductors and related systems.
