No abstract

With the aim of finding a low-cost, safe, and reliable way to reduce costs of space launch, a maglev launch assist vehicle (Maglifter) is proposed. We present a permanent magnet–high temperature superconductor (PM-HTS) interaction maglev system for the Maglifter, which consists of a cryostat with multi-block YBaCuO bulks and a flux-collecting PM guideway. We obtain an optimum bulk arrangement by measuring and analysing the typical locations of HTSs above the PM guideway. We also measure the levitation abilities of the arrangement at different field cooled heights (FCHs) and different measuring distances (MDs), and find that the lower FCH and the lower MD both cause more magnetic flux to penetrate the HTSs, and then cause stronger lateral stability. A demonstration PM-HTS maglev test vehicle is built with four maglev units and two PM guideways with the length of 7 m. Its levitation characteristics in different FC and loading conditions are demonstrated. By analysing the maglev launch assist process, we assess that the low FC is useful for increasing the lateral stability of the Maglifter.

Various Maglev launch assist concepts were proposed in the world for the aim to find low-cost, safe, and reliable ways to get to space. Among them, high temperature superconducting (HTS) bulk magnetic levitation platform was considered as a better one for Maglev launch assist because of its inherent stability both in the vertical and lateral directions. As a primary work, a demo HTS Maglev launch assist test vehicle was designed and constructed in our laboratory. The system includes a vehicle body, permanent magnet guideway with the length of 7 m, the acceleration and braking parts. HTS bulks were located in LN 2 vessels fixed below the vehicle body. The levitation force larger than 50 kg was provided by the interaction between HTS bulks and NdFeB guideway. The HTS bulk arrangement was optimized by measuring and comparing static and dynamic levitating characteristics of different HTS bulk units on NdFeB guideway. The acceleration part of the system was achieved by the linear motor. The braking was achieved by a set of spring buffer. The experimental investigation was carried out by the system, and some results were presented in the paper.Index Terms-High-temperature superconductors, launch systems, magnetic launch assist, magnetic levitation.

In order to investigate the feasible application of a permanent magnet–high-temperature superconductor (PM–HTS) interaction maglev system to a maglev train or a space vehicle launcher, we have constructed a demonstration maglev test vehicle. The force dissipation and damping of the maglev vehicle against external disturbances are studied in a wide range of amplitudes and frequencies by using a sine vibration testing set-up. The dynamic levitation force shows a typical hysteresis behavior, and the force loss is regarded as the hysteresis loss, which is believed to be due to flux motions in superconductors. In this study, we find that the hysteresis loss has weak frequency dependence at small amplitudes and that the dependence increases as the amplitude grows. To analyze the damping properties of the maglev vehicle at different field cooling (FC) conditions, we also employ a transient vibration testing technique. The maglev vehicle shows a very weak damping behavior, and the damping is almost unaffected by the trapped flux of the HTSs in different FC conditions, which is believed to be attributed to the strong pinning in melt-textured HTSs.