Development of Test Setup for I-V Characterization of High-Temperature Superconductor Under Strain

Recently, there has been a focus on the development of power devices using high-temperature superconductors (HTSs) such as superconducting cables, superconducting magnetic energy storage (SMES) systems, superconducting motors, and generators since no joule loss occurs during operation. HTS is said to replace LTS in fusion reactors. Second-generation (2G) HTS has a very thin tape-like composite layered structure. Before the design of devices made out of HTS tape, the electromechanical properties of HTS tape are required. One such property is the I-V characterization of tape under tensile strain. As tape undergoes a state of stress during operation, the knowledge of the degree of degradation of current carrying capacity due to this is of utmost importance. A test setup for I-V characterization under tensile strain is developed by modifying the existing universal testing machine (UTM). This cryogenic UTM (C-UTM) can test stress–strain and I-V characterization of YBCO-based 2G HTS tape under varying strain at 77 K. Experimental procedure and instrumentation are discussed. A SuperPower make 2G HTS tape was tested in this UTM, and the result is compared with the available literature and manufacturer data sheet. This setup will be very helpful for testing the new HTS tape model for which experimental data are not yet present in the literature. A scanning Hall probe microscopy (SHPM) was also utilized to obtain the critical current variation along the length of the deformed test HTS sample. The HTS tape has undergone complete degradation along its length as a result of the applied longitudinal strain.