  Large high field superconducting magnets often requires high current
superconducting cables. In order to develop these cables, a facility capable of
providing high magnetic field with large sampling area as well as electrical
current of tens of kA is essential. A superconducting transformer is an
energy-efficient and low-cost way to provide large current to superconducting
cables. Previously, we co-developed a superconducting transformer and
successfully tested it to a maximum output current of 45 kA in zero magnetic
field. In this work, this superconducting transformer is installed to the 12 T
split solenoid magnet at the National High Magnetic Field Laboratory (NHMFL).
We calibrated it by using this facility to measure critical current of a NbTi
Rutherford cable as a function of magnetic field up to 10 T, and compare the
results with those available in the literature. In addition, a strand extracted
from the NbTi cable is tested for critical current. The critical current of the
extracted strand is scaled and compared with critical current of the cable. The
accuracy of the critical current measurement using this superconducting
transformer is discussed in detail. This work concludes the commissioning of
this superconducting transformer which combined with the 12 T split magnet will
provide unique cable testing capability for future cable development for the
NHMFL and its users.
