Superconducting quantum interference devices based on YBa2Cu3O7–x films for nondestructive testing

Abstract

Original superconducting quantum interference devices (SQUIDs) with a working temperature of 77 K based on high-temperature superconducting (HTSC) YBa₂Cu₃O_7–x films can be used for the measurement systems of nondestructive testing using magnetic and eddy-current methods. A dynamic range of 120 dB with respect to the amplitude of the measured signal and a spatial resolution of about 10 µm are reached for the measurement system with the HTSC SQUID in which a receiving loop with a size of 50 µm is placed at a distance of about 0.3 mm from the room-temperature object under study. The sensitivity with respect to magnetic field (4 fT/ \(\sqrt {Hz} \) at a temperature of 77 K) of the HTSC SQUID magnetometer with multilayer superconducting flux transformer is sufficient for applications in biomagnetic measurements in magnetocardiography and magnetoencephalography. HTSC SQUID gradiometers with multilayer superconducting flux transformers exhibit stable operation in magnetically unshielded space at a sensitivity of 15 fT/cm \(\sqrt {Hz} \) with respect to the gradient of magnetic field at 77 K. Such a sensitivity is sufficient for the detection of single magnetic particles with a size of about 10 µm at a distance of about 15 mm.