MAGNETIC LEVITATION TECHNOLOGY AND ITS APPLICATIONS IN EXPLORATION PROJECTS Quan-Sheng Shu a Guangfeng Cheng a , Joseph T. Susta a , John R. Hull b , James E. Fesmire c , Stan D. Augustynowicz d , Jonathan A. Demko e , Frank N. Werfel f a AMAC International Inc.. Newport News. VA 23606, USA b Downers Grove, IL 60516, USA c NASA Kennedy Space Center, FL 32899, USA d Sierra Lobo Inc. at NASA KSC, NASA Kennedy Space Center, FL 32899. USA e Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA f Adelwitz Technologiezentrum GmbH, Rittergut Adelwitz. 04886 Adelwitz, Germany Receied 26 October 2005; accepted 27 October 2005 Abstract An energy efficient cryogenic transfer line with magnetic suspension has been prototyped and cryogenically tested The prototype transfer line exhibits cryogen saving potential of 30-35% in its suspension state as compared to its solid support state. Key technologies developed include novel magnetic levitation using multiple-pole high temperature superconductor (HTS) and rare earth permanent-magnet (PM) elements and a smart cryogenic actuator as the warm support structure. These technologies have vast applications in extremely low thermal leak cryogenic storage/delivery containers, superconducting magnetic bearings, smart thermal switches, etc. This paper reviews the development work and discusses future applications of established technologies. Keywords: Magnetic levitation; High TC superconductors; Cryostats; Space cryogenics; Superconducting bearings 1. INTRODUCTION More and more applications [1-3] of magnetic levitation (MagLev) technology have been exploited in extensive cryogenic engineering domains. As one instance of such endeavors, AMAC International Inc.'s team of scientists and researchers has successfully applied magnetic levitation using HTS and high strength PM in an energy efficient prototype of a cryogen transfer line [4-8]. The key design issues, such as optimization of levitation unit and "smart" support structure development, are reviewed in this paper. Cryogenic test results are reported as well. The advantages of non-contact insulation through magnetic levitation support enable the associated technologies to promise low thermal loss solutions for space flight vehicles and/or planetary surface operation stations. As an example, the magnetic levitation technology as developed by AMAC can be extended to the design of zero-boil-off (ZBO) cryotanks [3,9-11] that impose much lower cooling power demands on equipped cryocoolers. Also, the fact that cryocoolers are becoming more and more reliable makes it feasible to build flywheels consisting of passive superconducting magnetic bearings (SMBs) [1,2], i.e. bearings composed of tubular HTS and PM, that can be used in space energy storage systems. A comparison of popular magnetic bearing techniques is given in this paper to demonstrate the benefits that a passive magnetic bearing may produce. Implementation of a transfer line with magnetic levitation units triggered the question of smart support design, which provides mechanical support when it is so warm that HTS-PM units are deactivated. As a consequence of such studies, a cryogenic actuator made of smart material has been prototyped and tested. Its motion is passively adjusted by temperature change in the system. No powered control units are required. No manual operations are needed either. The design principles of such a smart cryogenic actuator can be adapted for design of automatic thermal conduction switches used in cryogen storage containers, cryogenic valves, seals, and some medical applications. 2. DESIGN OF CRYOGENIC TRANSFER LINE WITH MAGNETIC SUSPENSION This Section summarizes the primary considerations on three aspects, i.e. magnetic levitation configuration, Cryogenics, Vol. 46, Issue 2-3, p105, 2006. 0011-2275/$-see front matter © 2005 Elsevier Ltd.