Research On Temperature Control Technology Of CPT Magnetometer

Coherent Population Trapping(CPT)atomic magnetometer is an all-optical atomic magnetometer that measures the external magnetic field by the Zeeman effect,as well as the CPT resonance signal of the working element in the atomic cell of the magnetometer.Therefore,the atom density of the working element in the atom cell is directly related to the quality of the magnetic signal and thus affects the measurement sensitivity and accuracy.This requires a temperature control system for the magnetic sensor,which can not only control the magnetic sensor atomic cell operating temperature,but also produce smaller or little interference magnetic field.In order to improve the temperature stability of the working environment of the atomic magnetometer sensor and improve the sensitivity and accuracy of the magnetometer,a non-magnetic heating technology based on digital PID algorithm is proposed,and the temperature control system of the atomic cell functioning a high precision of the magnetometer heating and temperature control is designed.Firstly,this paper introduces the background of the topic,and summarizes several common atomic magnetometers especially the CPT atomic magnetometers and their research progress.At the same time,the heating method of the atomic cell used in the atomic magnetometer is studied and summarized,and the basic working principle of each heating mode and their respective characteristics are briefly introduced as well.Secondly,the working principle of CPT atomic magnetometer is expounded,using the sensitivity formula of atomic magnetometer and the variation curve of atomic gas with temperature in temperature cell,the temperature control requirements and necessity of atomic magnetometer are studied and analyzed.And the technical indicators of the temperature control system is proposed.Then,the design of the system is completed and the performance of the system is verified by simulation.The finite element thermal simulation of the atomic magnetometer sensor is carried out.The transfer function is determined through fitting the thermodynamic parameters by Matlab least square function method.Using the Simulink tool of Matlab,the control system model is set up and the parameters are debugged and simulated to determine the optimal control parameter combination.The simulation proves that the temperature control accuracy is better than ± 0.05 ° C,which verifies the feasibility and stability of the control system under the low power requirement.Finally,Using the control parameters obtained by simulation of the control system,the temperature heating effect and temperature control performance of the temperature control system of the magnetic sensor is verified,and compared with the simulation results.The experiments' results show that the temperature control system can meet the temperature control demand with good adaptability and stability,and the maximum peak-to-peak value of the system after steady-state fluctuation is within 0.35 ° C.The realization and verification of the temperature control system also provide a new design idea and feasibility scheme for the temperature control of other types of atomic magnetometers.