Development of a superconducting magnet excited with thermoelectric conversion element for quasi persistent mode

Some superconducting magnets are generally operated in persistent mode. The persistent-mode operation of these magnets is necessary to maintain field decay rates below a certain level, typically 0.01 ppm over a 1-hr period. These magnets used to be physically uncoupled from the external power source. In the case of HTS magnets, it is very difficult to keep the magnetic field stable without a high-stability external power source for large flux flow losses. A superconducting magnet is a high current and low voltage system except for excitation voltage. From this point of view, a thermoelectric conversion element is a very suitable power supply for a quasi persistent-mode magnet system. Moreover, this element seems to be particularly useful for HTS magnets. As the first step of this study, the authors tried to design a superconducting magnet excited with a thermoelectric conversion element and carried out an excitation test of a small HTS magnet by using the elements.