核磁共振陀螺中内嵌碱金属磁力仪研究

Research on Alkali Metal Magnetometer for Nuclear Magnetic Resonance Gyroscope

核磁共振陀螺利用核自旋的闭环磁共振实现角速度的测量,其磁共振信号一般由内嵌碱金属磁力仪测出。为了提高磁力仪性能,对描述磁力仪的Bloch方程,采用微扰迭代法和级数展开法,求出了各磁矩分量的近似解,然后讨论了线性测量范围随纵向与横向弛豫时间的变化规律以及频率响应特性。利用数值仿真,对上述近似解析解进行了验证。结果表明,磁力仪的线性测量范围随纵向、横向弛豫时间的增大而减小,其频率响应为一阶低通,截止频率仅与横向弛豫时间有关。上述研究对核磁共振陀螺的优化有一定的参考意义。

Nuclear magnetic resonance gyroscope measures angular rates with close loop magnetic resonance,where the magnetic resonance signal is read out with embedded alkali metal magnetometer.In order to improve the performance of the magnetometer,the Bloch Equations are solved with perturbation-iteration and series expansion method.Each component of the magnetic moment is obtained approximately.Then the linear measurement range as a function of longitudinal and transverse relaxation time is discussed.Moreover,the frequency response of the magnetometer is obtained.The approximate solution is verified with numerical simulation.It is found that the linear measurement range decreases when longitudinal and transverse relaxation time increases.The frequency response of the magnetometer is similar to one-order low pass filter and the cut-off frequency is related to transverse relaxation time.These findings is of significance to the optimization of nuclear magnetic resonance gyroscope.