Research On The Electromagnetic Characteristics Of The Second Generation HTS Tape

The development prospect of the 2nd generation high-temperature superconductor (HTS), so called 2nd HTS, has advantages over the 1st generation BSCOO one due to its higher transport capacity, more excellent characteristics such as less anisotropy and expected lower price. In order to improve its application, it is essential to do detailed research in the electromagnetic characteristics. This paper presents the basic electromagnetic characteristics of the practical 2nd generation HTS coated conductor (YBCO CC) in liquid nitrogen temperature. The main contents are included as the followings:1. The experimental set-up was constructed to measure electromanetic characteristics of HTS tapes. The measurment systems for anisotropic properties of the YBCO CC and current disstribution connected in parallel were finished, the controllable system and data acquisition were realized by virtual instrument control software (VI).2. The anisotropy of YBCO CC was experimentally studied in DC magntic field. The critical current and n value were obtained in different magnitude and orientaion of magnetic field. By fitting the measuring data, we found the empirical formulae for calculation of critical currents and n values. Based on these models,critical current and n value distributions of a double-pancake (DP), made of YBCO CC, were simulated and measured. The simulated results were good agreement with the tested ones, which veified the effectiveness of ansotropic models. Additionally, the optical transport current of the DP was obtained by comparing the experimental and calculative index loss.3. In superconducting electrical engineering, jointing and soldering between superconductors is important technique which determines the safety and efficiency of superconducting apparatus. The soldering techniques of YBCO CC were performed and tested. The dependence of jointing resistances on length of overlap was obtained then we compared the experimental and calculative data and acquired the optimum length of overlap by various soldering techniques with different overlap.4. Current distribution among HTS tapes with different characteristics such as critical currents and n values were tested by connecting them in parallel. On the other hand, the current distributions were also simulated by modeling the tapes connected in parallel using the software PSCAD. The results indicate that the current has ability of self-regulation influenced by critical current and n value.