Characteristic Analysis of Directly Coupled HTS dc-SQUID Magnetometer With Superconducting Film Magnetic-Shield Considering Josephson-Junction Resistance

A high temperature superconducting quantum interface device (HTS SQUID) is an extremely sensitive magnetic sensor. The HTS SQUID is required to have a high robustness with respect to magnetic noise for stable operation outside a magnetic shielding room. In order to achieve the high robustness of HTS SQUID, use of a magnetic shield with a superconducting film has been proposed, and its effectiveness has been confirmed in the experiments. In this paper, an electromagnetic field simulation was performed using the 3-D edge finite element method to confirm the effectiveness of the superconducting film magnetic-shield. Since both the SQUID magnetometer and the superconducting film magnetic-shield are made of HTS, it is required to consider the HTS characteristics in the electromagnetic field simulation. Additionally, the SQUID magnetometer has Josephson junction. In this paper, the property of the Josephson junction is also considered. The simulation accuracy depending on the type of the finite element mesh is also investigated.