Magnetic noise modeling and calculation of Fe-based nanocrystalline in the SERF magnetometer considering temperature effects

Abstract

The Fe-based nanocrystalline has been widely used in the innermost magnetic shielding of the spin-exchange relaxation-free (SERF) magnetometer due to its high permeability and low magnetic noise, which are significant factors limiting the sensitivity and accuracy of the measurements. However, the operating temperature of the inner shielding layer is around 80°C, and temperature has a significant impact on the magnetic noise of Fe-based nanocrystalline. To precisely analyze the magnetic noise of the Fe-based nanocrystalline in the SERF magnetometer, we first numerically simulate the 1K107 Fe-based nanocrystalline magnetic shielding barrel using the finite element method (FEM). Then, a variable-temperature dynamic Jiles-Atherton (VTDJA) model is proposed. The losses of 1K107 under various temperature are separated. The magnetic noise of 1K107 is computed using the Fluctuation-Dissipation theory. Finally, the magnetic noises of 1K107 at 25℃ and 80℃ are measured by setting up an experimental test system. Results show that the simulated deviation of the magnetic noise at 80°C and 25°C is 32 %, and the actual measured deviation is 48 %. The errors between simulated and measured magnetic noises at 25°C and 80°C are 5.29 % and 6.54 %, respectively. This study provides a novel method for the performance optimization of the SERF magnetometer.