Magnetometer exploiting inductance modulation in coils made of high-critical-temperature superconductor

摘要

We developed a magnetometer for measuring low-frequency magnetic fields. The magnetometer consists of two coils, namely, pickup and modulation coils made of high-critical-temperature superconducting material. The inductance of the modulation coil is modulated with time, and the magnetic field signal is converted to an amplitude-modulated voltage across the modulation coil. The prototype magnetometer can operate at low frequencies down to f = 0.01 Hz without diminishing the response. The noise in the magnetic field signal is 40 pT/Hz(1/2) at 10 Hz. An order of magnitude improvement will be possible with a modulation coil of suitable geometry. (C) 2017 The Japan Society of Applied Physics