基于碱金属磁力仪的铷原子横向弛豫时间测量方法

Measuring method of rubidium atom transverse relaxation time based on alkali metal magnetometer

原子气室是核磁共振陀螺核心部件,微小尺寸气室工作原子之间碰撞以及Rb原子与气室内壁的碰撞会导致Rb原子的横向弛豫时间大幅降低,限制惰性气体共振信号幅值及陀螺精度的提升。传统的三种弛豫时间测量方法均需要高频激励磁场,操作复杂且精度低。针对上述问题,在分析传统横向弛豫时间测量方法的基础上,提出基于铷原子磁力仪的横向弛豫时间测量方法。搭建数理模型对方案进行可行性验证,测量误差小于0.4‰。在实验中,对三支充气参数不同的气室的横向弛豫时间进行测量,测量显示组间误差小于6.8‰。与自由感应衰减方法测量结果相比,两者差别不超过5%,且操作更为简单。理论仿真和实验结果均表明所提出的方法能准确测量气室内铷原子横向弛豫时间,为核磁共振陀螺气室参数优化提供了工程化测量方法.

Atomic gas cell is the core component of nuclear magnetic resonance gyroscope.In the small size cell,the collision between working atoms and collision between alkali metal atoms and the wall of cell can greatly reduce the transverse relaxation time(T_(2))of Rb atom,which limits the improvement of amplitude of resonance signal and the improvement gyro accuracy.The three traditional T_(2)measurement methods all require high frequency excitation magnetic field,which lead to complex operation and lower accuracy.Based on the analysis of the traditional methods,a new method for measuring T_(2)based on Rb magnetometer is proposed.A mathematical model is built to verify feasibility of the scheme,the measurement error is less than 0.4‰.In the experiment,the T_(2)of three cell with different charging parameters are measured by the proposed method,the error between the measurement results is less than 6.8‰,and the difference between them is less than 5%compared with the measurement results by the free induction decay method.The results of the theoretical simulation and experiment measurement results show that the proposed method can accuracy measure the T_(2)of Rb atom,which provide an engineer measuring method for the optimization of cell parameters in the nuclear magnetic resonance gyroscope.