The Theory And Simulation Study Of Faraday Rotation Spectroscopy Based On Permanent Magnetic Rings

Faraday Rotation Spectroscopy(FRS)for the detection of trace gas,especially various paramagnetic particles(NO,NO2,OH,H2O2 etc.)has returned to the forefront of research in the last few decades,with rapid development and widespread application,which has shown extraordinary expansion and diversification.Researchers are constantly striving for the quantum limit of spectral detection,which is still at a distance from this sensitivity.As a result,a number of solutions have been proposed to achieve quantum noise levels by combining traditional spectroscopic detection techniques with some sophisticated measurement methods.Faraday rotational spectroscopy has shown the way to this combination.Faraday rotation spectroscopy is a spectroscopic technique suitable for the highly selective and sensitive detection of various paramagnetic molecules.In recent years,with the development of laser technology,Faraday rotation spectroscopy has been rapidly developed,and various technical methods have emerged to enhance the detection performance in order to achieve quantum noise level detection performance.This thesis focuses on the theoretical analysis and simulation of Faraday magnetic rotational spectroscopy based on a static magnetic field constructed by a permanent magnet ring,in order to provide a reference for the development of Faraday rotation spectroscopy with a static magnetic field which has low energy consumption.First of all,signal calculations for Faraday rotation spectroscopy are investigated.The spectral positions of the Faraday rotation spectroscopy signal are determined by calculating the splitting and shifting of the energy levels due to the Zeeman effect;the Faraday rotation spectroscopy signal consists of an intensity part and a line shape part:the signal intensity is calculated by using the integrated line intensity,the signal line shape is calculated by using the real part of the plasma dispersion function,and the spreading factors affecting the signal are taken into account by parameter adjustment.Additionally,a scheme for the construction of the magnetic field based on permanent magnet rings is developed.The magnetic ring arrays are considered to be fully equal,equal inner and outer diameter,and equal inner diameter only,and for different combinations of different types of magnetic ring groups:spacing optimisation based on fully equal magnetic rings,specification optimisation based on equal inner and outer diameter magnetic rings,and ring group optimisation with mixed magnetic ring specifications.Finally,the work of this paper and the innovative points of the paper are summarized and an outlook on the future of Faraday rotation spectroscopy is given.