Research On The Measurement Of Key Performance Indexes Of Superconducting/TMR Composite Magnetic Sensor

With the rapid development of weak magnetic sensing technology,the new superconducting/magnetoresistance composite magnetic sensor is proposed.Its detection accuracy can be close to the level of SQUIDs.At the same time,this kind of magnetic sensor has the advantages of small volume,simple structure and stable performance.It has great development potential in the future.However,there is a lack of comprehensive and accurate performance evaluation methods and measurement systems for the composite magnetic sensors.Therefore,focusing on the key performance index test of superconducting/TMR composite magnetic sensor,this paper carries out the research on the measurement method of static characteristics and noise characteristics of composite magnetic sensor,the design and construction of measurement system,and the performance measurement and evaluation of composite magnetic sensor.The main research contents are as follows:The measurement and analysis methods of static characteristics and noise characteristics of composite magnetic sensor are established.By deeply analyzing the working principle of the composite magnetic sensor,the index system of static characteristics and noise characteristics is established;The characteristics of magnetoresistance response curve are analyzed,and the evaluation methods of static indexes such as sensitivity,superconducting magnetic field magnification and superconducting saturated magnetic field are proposed;The principle of noise spectrum measurement based on FFT is analyzed,and two resolution measurement methods based on sensitivity and reference magnetic field are proposed.An automatic measurement system for static and noise characteristics of composite magnetic sensors with high precision and strong anti-interference ability is designed and built.The design of cryogenic device,AC/DC magnetic field source,magnetoresistance response measurement device and noise measurement device is systematically studied.The accuracy and anti-interference ability of the measurement system is improved by means of high-precision instrument selection,magnetic field source calibration,filter amplification circuit design and double magnetic shielding.The problems of AC magnetic field source design and electromagnetic coupling interference suppression are solved;A set of measurement program based on Lab VIEW is designed to realize the rapid measurement of magnetoresistance response curve and noise spectrum.After systematical measurement and evaluation,the magnetic noise of the built measurement system is 15p T and the electrical noise is 6.08 n V/Hz^0.5 to meet the testing requirements of static characteristics and noise characteristics of composite magnetic sensor.The static characteristics and noise characteristics of the superconducting/TMR composite magnetic sensor are measured and analyzed.Firstly,based on the finite element simulation method of E-J power exponent model,a composite magnetic sensor structure is designed,and the composite magnetic sensor is prepared by micro nano machining process;The static characteristics and noise characteristics of the prepared sensor are tested by using the built composite magnetic sensor measurement system.The static characteristics and noise characteristics of the sensor are systematically evaluated.At 77K,110μA operating current,the sensitivity is 598%/m T,the magnification of superconducting magnetic field is 75,the superconducting saturated magnetic field is0.05 m T,and the resolution is 208 p T@10Hz,the principle verification of superconducting/TMR composite magnetic sensor is realized;The influence of working current on the performance of the sensor is tested and analyzed,and the law that the key performance of the sensor does not depend on the working current is obtained.