Test device and method for initial permeability of ferrite imaginary part at extremely weak magnetic field and extremely low frequency

Abstract

The invention discloses a device and method for testing the initial permeability of the imaginary part of ferrite at extremely weak and extremely low frequencies. The test is helpful to improve the measurement accuracy of the initial magnetic permeability of the imaginary part of the ferrite and reduce the measurement error of the magnetic noise of the shielding barrel. The uniform coil shell is used to ensure that the measuring coil is evenly wound, and the interference factors are eliminated to the greatest extent; the ferrite box to be tested is placed in the center of the magnetic shielding barrel by using an L-shaped frame to ensure an extremely weak magnetic environment during actual use; The Jordan separation method can ensure the separation of the residual loss under extremely low frequency conditions, and finally the imaginary part initial permeability of the ferrite ring is obtained by using the relationship between the derived imaginary part permeability and the residual loss.

Description

technical field [0001] The invention relates to the technical field of magnetic permeability measurement, in particular to a device and method for measuring the initial magnetic permeability of the imaginary part of ferrite at extremely weak magnetic field and extremely low frequency, especially suitable for ferrite magnetic materials used in quantum precision measurement devices Low-frequency complex permeability measurements. Background technique [0002] A weak magnetic environment is a necessary condition for the current quantum precision measurement device to achieve ultra-high sensitivity. A magnetic shield made of a high magnetic permeability material is an effective way to achieve a weak magnetic environment. Therefore, 3-5 layers of permalloy barrels are generally used for shielded from the geomagnetic environment. In addition, the suppression of noise plays a key role in realizing the ultra-high sensitivity of quantum precision measurement devices. Although permal...

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Problems solved by technology

However, it is usually impossible to generate a magnetic field with an amplitude close to zero. The real initial permeability can only be estimated by using the extrapolation method in combination with the Rayleigh formula. This estimation method is for the real part of the initial permeability It is relatively accurate, but there is no corresponding theoretical support for the imaginary part of the initial magnetic permeability. Therefore, the imaginary part magnetic permeability measured by the existing method is not rigorous and accurate, which will have a great impact on the noise evaluation of the quantum precision measurement device.

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