A high-field bipolar loss measurement apparatus

An apparatus has been constructed to measure dissipation in superconducting wire in high alternating fields. The apparatus will be used to make measurements on conductors which must operate in fields up to 7.0 T and rates of field change up to 15 T/s. The magnet for this facility is wound of uninsulated, 15 strand Rutherford cable in which the strand is a 0.812 mm diameter, fully mixed matrix, Cu plus CuNi, multifilament NbTi conductor. The coil is wound in a bath cooled configuration with an overall current density of 7.8 kA/cm². The circuit incorporates a pair of locomotive traction motors as the capacitive circuit element for the bipolar swing. The design, construction and operating characteristics of the field coil and the associated circuitry are described.