A novel low-noise Mu-metal magnetic shield with winding shape

The spin-exchange relaxation-free (SERF) co-magnetometers have promising applications in both inertial navigation and fundamental physics experiments. However, the ﬂuctuation in the spin polarization caused by the probe beam has a non-negligible inﬂuence on the co-magnetometer signal. In this paper, a theoretical model containing three parameters of the probe beam is established by extending the coupled Bloch equations. Based on this model, the inﬂuences of probe power density on the transient and steady-state response of a SERF co-magnetometer are analyzed. According to the transient response model, a new measurement method for transverse optical pumping of the probe beam is proposed. Then for the steady-state response model, a steady-state error suppression method is suggested by adjusting the degree of circular polarization of the probe beam. Eventually, the suppression method is used to reﬁne the SERF co-magnetometer and achieves a suppression rate of 70.31% in transverse electron spin polarization ﬂuctuations, thus improving the co-magnetometer to a stability of 0.0079°/h. In our knowledge, it is better than what has been reported so far.

Section: Methodsmentioning

confidence: 99%

Probe beam influence on spin polarization in spin-exchange relaxation-free co-magnetometers

Wei

Xing

Zhai

et al. 2023

“…Its SF at 0.1 Hz is approximately 191, and the residual field in shield is 4.2 nT, a factor of 13 000 smaller than geomagnetic field. Ma et al designed and fabricated a novel cylindrical magnetic shield with a winding shape, and its static SF is increased by 123% compared to the conventional structures [19]. Holmes et al presented a lightweight MSR design composed of two layers of Mu-metal and one layer of copper with an SF (@0.01 Hz) of 158 and a residual field of 4.8 nT, which is about 10 331 times less than geomagnetic field [20].…”

Section: Introductionmentioning

confidence: 99%

Experimental studies on the performance of magnetic shields under different magnetization conditions

Yang¹,

Zhang²,

Shi³

et al. 2023

Self Cite

In recent decades, magnetic shields have provided basic experimental environments for the measurements of extremely weak magnetic fields represented by the biological magnetic signal. Excellent shielding performances, including the low residual field and high shielding factor, are necessary to ensure the quality of these weak magnetic signals and avoid the interference of external magnetic field. The magnetic shielding performance of the same device can be affected by the different degaussing and test conditions, which remains systematically studied. In this paper, the experiments with variable magnetization conditions, including different degaussing orders, test fields and environmental fields, are established in a nearly zero-field space to simulate the different situations during measurement. The residual field and shielding factor of the cubic shielding device are tested in these cases. Meanwhile, these shielding performances are analyzed from the perspective of the magnetization state and calculated based on the magnetic properties which are tested and fitted by Jiles-Atherton model. The results show the influence of these different conditions on the shielding performances of the cubic device, consistent with the numerical calculation. Under the same environmental field, the different degaussing order and test field lead to completely different residual field and shielding performance, respectively. The influence of the earth magnetic field on the shielding factor can be ignored due to its tiny equivalent bias field determined by the anhysteretic magnetization curve.

“…Magnetic shielding devices are widely applied in extensively fields, including basic physics [1], geophysics [2], biomedical science [3] and national defense applications [4]. For example, Passive magnetic shielding devices weaken the influence of external MF on the residual MF inside the magnetic shielding device through the high permeability material's flux shunt effect [10,11]. So, the permeability of shielding materials determines the shielding effect, which is an important parameter for residual MF of magnetic shielding devices.…”

Section: Introductionmentioning

confidence: 99%

Measurement and analysis of an optimized Jiles–Atherton model considering the influence of temperature applied in magnetic shielding devices

Sun

Ren

Zhou

2023

The magnetic shielding devices works at different temperatures due to the influence of gas chamber and environmental temperature in the application of ultra-highly sensitive spin exchange relaxation free (SERF) magnetometer. To accurately evaluate the residual magnetic field of magnetic shielding device at different temperatures, it is necessary to build the magnetization model considering temperature. However, the modelling of permalloy’s magnetization properties and the measurement of residual magnetic field in magnetic shielding devices at different temperatures haven’t been considered. In this paper, the optimized Jiles-Atherton model of permalloy considering temperature is constructed in which parameters are extracted by particle swarm optimization algorithm. To further verify the effectiveness of the model in the magnetic shielding device, it is applied to the residual magnetic field simulation of magnetic shielding devices and verified by measurement. The optimized Jiles-Atherton model considering temperature improves the calculation accuracy of magnetic shielding devices, which is of great significance for the application of ultra-highly sensitive SERF magnetometers.