High Temperature Superconducting Maglev Measurement System
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Three high temperature superconducting (HTS) Maglev measurement systems were successfully developed in the Applied Superconductivity Laboratory (ASCLab) of Southwest Jiaotong University, P. R. China. These systems include liquid nitrogen vessel, Permanent Magnet Guideway (PMG), data collection and processing, mechanical drive and Autocontrol features. This chapter described the three different measuring systems along with their theory of operations and workflow. The SCML-01 HTS Maglev measurement system can make real time measurement of Maglev properties between one or many YBCO bulks and employ a PM or PMG. Also the trapping flux of high Tc superconductors can be measured in the scanning range of 100 mm×100 mm. It was especially employed to develop the on board HTS Maglev equipment which travels over one or two PMGs. The on board Maglev equipment includes a rectangular-shaped liquid nitrogen vessel and YBCO bulk superconductors. Based on the original research results from the SCML-01, the first man-loading HTS Maglev test vehicle in the world was successfully developed in 2000. In order to make more thorough and careful research investigations, the HTS Maglev, HTS Maglev Measurement System (SCML-02) was subsequently developed with even more function capabilities and a higher precision to extensively investigate the Maglev properties of YBCO bulk samples over a PM or PMG. The new features included: higher measurement precision, instant measurement at movement of the measured HTS sample, automatic measurement of both levitation and guidance forces, dynamic rigidity, ability for the measured HTS sample to be moved along the three principal axes all at once, relaxation measurements of both levitation and guidance forces, and so on. The main specification of the system is: position precision ±0.05 mm. vertical force precision 2 ; horizontal force precision 1 ; and force measurement precision of 0.02 N. In order to investigate the dynamic characteristics behavior of the HTS Maglev engineering application, an HTS Maglev dynamic measurement system (SCML-03) was designed and successfully developed. The circular PMG is fixed along the circumferential direction of a big circular disk with a diameter of 1,500 mm. The maximum linear velocity of the PMG is about 300 km/h when the circular disk rotates round the central axis at 1280 rpm. The liquid nitrogen vessel with HTS bulks is placed above the PMG, and the vessel is allowed to move along the three main principal axes so that sensors can detect force variations stemming from the superconductors. The design, method, accuracy and results have allowed the successful development of these three measurement systems. All systems are calibrated by standard measurement technology, for which its reliability, stability, featured functions, and precision have also been validated through its long-term usage.