Conductor and vessel losses in bath cooled SMES systems

Several AC and DC loss sources are analyzed for superconductive magnetic energy storage (SMES) solenoids cooled in a bath of 1.8-K helium. The AC losses (eddy current losses) in the solenoid of the helium vessel and due to conductor stabilizer coupling loss are calculated for different charge or discharge sequences. The losses in the helium vessel are found for vessels both with and without an electric break. The analysis of DC loss for conductor joints takes into account several NbTi/Cu strands twisted around a high-purity aluminum stabilizer conductor. The resistance of the conductor joint depends on the electrical resistance of the bond between the strand and the aluminum and the distribution of joints staggered in position on the aluminum stabilizer