Study of 2G HTS superconducting coils using line front track approximation

This paper demonstrates an efficient method to calculate the ac losses in multipancake coils. We use the front track line to analyze stacked pancakes by assuming that the current fronts are straight lines and using the critical state model. The current distribution is solved by minimization of total magnetic energy. The calculated ac loss results are compared with the well-accepted H-formula in COMSOL. We further apply this model to the design of a SMES with 2 kJ, which is under construction. The object of the design is to maximize the stored energy and decrease the ac loss. We discuss the detailed geometry parameters and operation temperature with the validated numerical model. Our model provides a fast calculation method of ac loss in stacked (Re)BCO pancakes and is useful to HTS applications in high field magnets, energy storage devices, and electric machines.