Abstract
A solenoid magnetic field plays an important role in a non-line-of-sight azimuth transmission system based on polarization-maintaining fiber, which is directly related to the transmission accuracy of azimuth information. This research mainly studies the factors that affect the solenoid magnetic field according to the modulation signal from the direct current to the alternating current, as well as the hollow solenoid. First, the magnetic field components of the static solenoid are derived from the Biot–Savart law by using the uniform cylindrical current equivalent model. Then, the magnetic field of the near axial region is studied from the axial and radial directions, and the feasibility of calculating the magnetic field of the multi-layer solenoid with the superposition principle is verified by measuring the magnetic field of each position on the axis of the solenoid with a Gauss meter. Finally, the alternating electromagnetic field model is established using Maxwell’s equations, and the magnetic and electric fields of the hollow solenoid are further solved. The results show that the magnetic field in the middle part of the magneto-optic glass is more stable, and the magnetic collecting ability of the solenoid is stronger. The magnetic field intensity at the center of the magneto-optic modulation solenoid of the system is the largest, and it decreases with the distance from the center. The alternating electromagnetic field is closely related to frequency. The results provide a reference for the study of the azimuth accuracy of a non-line-of-sight azimuth transmission system.
Highlights
A solenoid magnetic field plays an important role in a non-line-of-sight azimuth transmission system based on polarization-maintaining fiber, which is directly related to the transmission accuracy of azimuth information
A non-line-of-sight azimuth transmission system based on polarization-maintaining fiber (PMF), combined with the Marius law for detecting an azimuth signal, can theoretically measure the angle between two or more devices without a mechanical connection for the condition of intervisibility, and this type of system is widely used in many fields, such as the initial alignment of a spacecraft launch, instrument measurement and tunnel engineering1
This paper mainly describes the study of the magnetic field produced by an electrified solenoid and discusses the static and alternating solenoid magnetic fields
Summary
It can be seen from Eqs. [11] and [12] that the expressions of the axial component Bz and the radial component Br are independent functions of φ . so, they can be written as Bz(r, z) and Br(r, z) , which fully reflects the cylindrical symmetry of the solenoid. As can be seen from Eq [13], there is no circumferential component in the solenoid magnetic field because the model uses a uniform cylindrical surface current equivalent, which is equivalent to the superposition of multiple ring currents in the axial direction. The circumferential magnetic field produced by the axial component of the current should be considered when the pitch of the solenoid is obvious, but the application of this kind of solenoid is rare. In the magneto-optical modulation system, when the magneto-optical material is installed, it is required to be coaxial with the solenoid at first and at the center of the solenoid At this time, the light emitted by the laser propagates along the central axis, passes through the magneto-optical glass, and forms a slender optical column with the length of glass. When studying the magnetic field in the paraxial region, its size and distribution are analyzed based on the axial and radial components
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