Study on Magneto-Resistance Sensors for Low Magnetic Field Measurements

• Published in: IEEE transactions on applied superconductivity Vol. 30; no. 4; p. 1
• Main Authors: Ueki, Ryuichi, Okada, Takafumi, Masuzawa, Mika, Tsuchiya, Kiyosumi, Kawamoto, Takashi, Umemori, Kensei, Kako, Eiji, Sakai, Hiroshi, Konomi, Taro
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ambient magnetic field; Continuous radiation; Flux expulsion; Liquid nitrogen; Mag-neto-resistance sensor; Magnetic field measurement; Magnetic fields; Magnetic flux; Magnetic sensors; Magnetometers; Power loss; Room temperature; Sensitivity; Sensors; Superconducting cavity; Surface resistance; Temperature sensors
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2020.2976994

High-Q operation of a superconducting radio frequency cavity can reduce power loss at the surface and is desirable for continuous-wave operation. To realize high-Q operation, the surface resistance, which is a sum of the Barden-Cooper-Schrieffer resistance and residual resistance, needs to be reduced. The residual resistance has been found to originate primarily from magnetic flux trapping in defects in the cavity during the cooling down process. A magnetometer called the "flux gate sensor" has been used to measure the ambient magnetic field; however, it is large in comparison with the cavity and it is very expensive. Sensors based on the magneto-resistance effect, such as Anisotropic-Magneto-Resistance (AMR) sensor, are smaller and much less expensive than a flux gate sensor. We examined the characteristics of magneto-resistance sensors at room temperature and liquid nitrogen temperature. The results are reported in this paper.