Saw-wave excitation eddy-current nde based on hts rf squid

Abstract

Using a high-temperature superconductor radio frequency superconducting quantum interference device planar gradiometer as the sensor, we developed a saw-tooth wave excitation eddy-current nondestructive evaluation device. By analyzing the amplitudes of harmonics in the response signal of the sample, we successfully detected the artificial defect in an aluminum plate and estimated the depth of the defect. We also demonstrated the possibility to construct the three-dimensional profile of a defect. In our program for data processing, we used a multiplying method to calculate the amplitudes of the harmonics, which was much faster than fast Fourier transform. During the experiment, the movement of -stage, data acquisition, and data processing could be done simultaneously.Index Terms-Eddy current, nondestructive evaluation (NDE), saw wave, superconducting quantum interference device (SQUID).