Measurement of AC profiles of magnetic field above HTSc tape using Hall probe technique with help of DAQ cards and triggering

Power applications of superconductors, such as transformers, power cables, motors, and generators require the study of the influence of AC magnetic fields on properties of high-temperature superconductors. Our contribution comprises a convenient method for a measurement of components of magnetic fields generated by induced currents circulating in a HTSc sample located in an AC magnetic field. Also, a data acquisition system is presented that allows for the measurement of signal proportional to the position and to the component of magnetic flux density by a Hall probe at a defined level of an applied magnetic field in each period simultaneously with the help of triggering. This differential Hall measurement enables us to acquire magnetic field profiles or maps in the vicinity of the sample corresponding to a certain value of the magnetic field applied. It is possible to obtain results for any value of the magnetic field applied in the course of the period, i.e. from zero up to a maximum value of the magnetic field at the rising or falling slopes according to trigger conditions. In particular, it can be used to investigate the current distribution in the sample during the AC cycle or defect detection in HTSc tapes.