Key Technology Studies Of Magnetic Shielding And Magnetic Compensation Based On Nitrogen-Vacancy Centers Magnetic Detection System

The solid-state spin of the diamond nitrogen vacant color center has high sensitivity and high spatial resolution in the field of weak magnetic detection.At the same time,NV atomic magnetometer has the potential great advantages of long spin coherent time,small volume,quick start,large working temperature range and high stability.These advantages attract the attention of many researchers.On the basis of this subject,the preparation technology of Nitrogen-Vacancy Centers,the shielding technology of electromagnetic and the three-dimensional Helmholtz coil which can produce high precision uniform magnetic field are studied in this paper.Firstly,in the preparation of Nitrogen-Vacancy Centers,the controllable preparation technology of the concentration and evenness degree of Nitrogen-Vacancy Centers in the magnetic measurement sensitive unit is studied.At this stage,the concentration of Nitrogen-Vacancy Centers can reach to 8ppm.At the same time,the law of the concentration of Nitrogen-Vacancy Centers with the dose of N ion implantation and electron injection is obtained.Secondly,this paper analyzes the magnetic measurement principle of Nitrogen-Vacancy Centers,and designs a scheme that can improve the accuracy and evenness of magnetic field.Based on the principle of electromagnetic shielding,an electromagnetic shielding device is designed for experimental needs.Using the three-dimensional finite element method(FEM)and the Ansoft 3D electromagnetic simulation software,the hollow cylindrical shielding model of high permeability material and high conductivity material is established,and the influence of various parameters on the shielding coefficient is analyzed.Final,selecting the optimal electromagnetic shielding scheme to design the machining shield,and the activeshielding test is carried out on the magnetic field of various environments.Finally,the related characteristics of Helmholtz coil and the principle of producing uniform field are studied.Ansoft and Matlab are used to simulate the Helmholtz coil.According to the simulation results,the distribution of uniform magnetic field and the intensity of uniform field in the coil are analyzed.A one-dimensional Helmholtz coil and a three-dimensional Helmholtz coil are designed and machined in combination with the simulation results and experimental requirements.In order to further improve the accuracy of the magnetic field applied to the Nitrogen-Vacancy Centers,a magnetic field control system is designed by using the Nitrogen-Vacancy Centers itself,which is sensitive to the magnetic field and compensated.