A Noncontact T_c Evaluation Technique Using a Hall Probe Array

A noncontact superconducting transition temperature (T_c) measurement system using a Hall probe array was devised to measure T_c of high-temperature superconductor (HTS) coated conductors (CCs) without physical contact to the surface, thereby avoiding contact with electrodes, which can cause damage to the conductor surface. The variations of the Hall voltage (V) distribution, which comes from the distribution of magnetic field on the surface of the CC, under a fixed applied field at different temperatures were used to estimate T_c. The measured T_c of the HTS GdBCO CC made by Sunam was approximately 93.2 K by the noncontact T_c method, as compared to approximately 93.5 K by the conventional four-probe-contact method in a commercial PPMS. Thus, the T_c obtained by this system is comparable with that from the transport four-probe method. In addition, the noncontact T_c measurement system devised and used in this study is simple because it does not need comparison and conversion with values measured by contact methods.