Modified Roebuck compression device for cryogenic refrigeration system of superconducting rotating machine

Abstract

Cryogenic refrigeration system installed on superconducting rotor has the merit that it can eliminate cryogen transfer between rapidly revolving rotor and stationary part and, therefore, the loss generated by it. Nevertheless, such an on-board cryogenic refrigeration system has not been realized yet because of the absence of compression device that can work reliably on rapidly revolving rotor. This paper presents the idea of modified Roebuck compression device as a potential on-board compression device. Although it has the disadvantage that it requires large radial space and external cooling and heating, a modified Roebuck compression device of 14 stages with diameter of 0.80 m mounted on a rotor revolving at 3600 rpm can produce substantially high compression ratio. J-T neon refrigeration system equipped with such a compression device can produce low temperature of 30 K and be useful for cooling superconducting rotor windings made of high temperature superconductor. (C) 2002 Published by Elsevier Science Ltd.