Optimization Methods for HTS DC and AC Cables With Longitudinal Magnetic Field Effect

A very important part of an HTS cable design is the optimization of its parameters to get the highest possible current-carrying capacity and stability. One of the possible ways to achieve it is the use of so-called longitudinal magnetic field effect. It is known that in magnetic fields that are parallel to a transport current, most of the superconductors, both low and high critical temperature ones, demonstrate the increase of the critical current. This effect was predicted for HTS theoretically and proved experimentally in our recent works. Although the longitudinal magnetic field effect can be used to increase the efficiency of both DC and AC HTS cables, their optimization methods should be different. In this paper, we present different optimization methods for DC and AC power cables with consideration of the longitudinal magnetic field effect, that can help to obtain the higher current-carrying capacity for DC cables and higher stability for AC power cables, i.e., lower AC loss. Two calculation methods of magnetic field in the cables are presented: analytical and with FEM model. Comparison of results of optimization DC and AC cables are presented and discussed. We also present the results of measurements and calculations of AC losses in DC cable.