Design and construction of the 4 Tesla background coil for the navy SMES cable test apparatus

The design and construction of a background coil being built by Westinghouse STC for the Navy SMES cable test apparatus are presented. One objective of the Navy SMES development program is to develop and test improved superconductors for SMES use. The background coil generates a 4 Tesla field on a 1.85 meter diameter SMES conductor sample. The coil stores 49.4 MJ, and has an inner diameter of 2.13 meters. The background coil and SMES conductor sample are housed in separate, concentric cryostats so that the SMES conductor samples can be changed without warming the background coil. The background coil is a pancake style winding, utilizing a Rutherford cable conductor cowound with a stainless steel strap and mylar insulation.