Operation of HTS SQUIDs with a portable cryostat: A SQUID system in conjunction with eddy current technique for non-destructive evaluation

We present a new design of a portable nitrogen cryostat for operation of moving SQUIDs. it mixture of liquid and gaseous nitrogen fills a reservoir in direct contact with a copper Dart for the SQUID integration, The temperature at the SQUID position is 77.8 K or 78.8 K depending on orientation, and varies within +/- 10 mK during lateral movement. The cryostat can operate as a pot-table system for 7 hours without refilling. Washer rf SQUIDs and de gradiometers were Integrated with the cryostat, We proved the operation of the system as a moving magnetometer in unshielded laboratory environment. Noise spectra in shielding and outside were independent of orientation. The system Tvas equipped with a differential eddy current excitation. We show the first non-destructive material evaluation results for fatigue crack detection on stationary samples with moving SQUID sensors.