Robot-Based NDE System Using 3D-Mobile HTS-SQUID

A novel HTS-SQUID gradiometer with ramp-edge Josephson junctions (JJs) composed of SmBa₂Cu₃O_y base-electrode and La₀₁Er_0.95Ba_1.95Cu₃O_y counter-electrode was developed. The robustness of the gradiometer in AC field perpendicular to the device plane was investigated. In an AC field of less than 2.8 mT_pp at 100 Hz, flux-trapping, jumping and increase in noise did not happen in the gradiometer, while a traditional HTS-SQUID gradiometer with YBa₂Cu₃O_7-x thin film and bicrystal JJs with the same dimension as the novel gradiometer could not be operated properly in an AC field of about several tens nT_pp. A robot-based NDE system utilizing the novel HTS-SQUID gradiometer was developed. The system could move the gradiometer three-dimensionally (3D) in an unshielded environment without magnetic shielding or compensation technique. Eddy-current-based detection of a through hole in magnetized stainless steel board was demonstrated by the robot-based HTS-SQUID NDE system.