Analysis of an on-line superconducting cryofan motor for indirect cooling by LH2

Abstract

This work relates to the study of an electrically powered cryofan for circulating close-loop cooling helium gas for superconducting applications with the following features: - Absence of any seal that can leak the pumped fluid or provide a path for heat transfer and require maintenance and/or is prone to failures. - The use of high temperature superconducting (HTS) stacks on the fan-rotor that, below critical temperature, can be magnetized contributing to the driving torque. The absence of electrically connected equipment as well as the lack of any seal, makes this arrangement especially suitable for reliable cryogenic helium gas circulation. Because HTS stacks cannot provide magnetic flux above Tc, during the initial stages of operation, in the presented study we analyse torque that will be provided by the passive iron components of the machine (reluctance torque, due to the saliency of the rotor) and by auxiliary permanent magnets or alternatively magnetizing coils