A study on stabilities of rotating magnets for superconducting generators

Abstract Stabilities of magnets in a high gravitational field up to 2000G at a rotating speed of 3, 600rpm, are studied to establish the fundamental design criterion of field windings of superconducting generators. It is clarified that magnet stability is greatly improved in a rotational field compared with stationary state, because of the enhancement of natural convection for the cooling of the coils caused by a high gravity. Heat transfer to liquid helium (LHe) are measured using a clean copper and a Formvar coated copper under rotational field. The coefficients are 0.7 × 10 4 Wm −2 K −1 and 0.4 × 10 4 Wm −2 K −1 at the gravitational field of about 1000G, respectively. They are almost identical to the calculated values based on the normal zone propagation velocities under the same condition.