AC loss calculation in REBCO coils or stacks by solving the equation of motion for current using an integration approach

The flux motion and its collective behaviour known as AC loss is the basic characteristic of high temperature superconducting (HTS) materials and controls the economic efficiency, stability and magnetic field uniformity of superconducting equipment. In so far, we have no method to calculate the AC loss of HTS devices in an efficient way. Normally, it will take days to simulate AC loss of HTS coils even with moderate number of turns. In this paper, we surprisingly found that an integral method is remarkably efficient in calculating AC loss of the coils in large scale. By comparing with the fastest method at present, the integral method is proved to be 4.4 times faster than the present one. We give the calculation details and discuss why this method has an advantage in calculating AC loss of the coil with a large number of turns. (paper)