【摘要】 卫星上测量地球磁场要求高精度的原子磁力仪具有全向测量能力,多数的单探头原子磁力仪不具备这一能力, CPT原子磁力仪理论上具有全向测量能力,但目前仍需要外部磁场方向参考,不能自主实现磁场的全向测量.本文提出了一种CPT原子磁力仪的分时扫描四峰双闭环控制方法,通过循环扫描+2,–2,+3和–3级CPT信号峰获得开环输出信号,并将4个CPT峰的开环输出处理形成两路控制回路的误差信号,一路求和用于校准0级中心频率,一路差分用于跟踪锁定±2,±3级CPT信号峰与0级信号峰之间的微波频率差.当磁场方向变化导致平行模式对应的±2级CPT信号峰消失时,通过±3级CPT信号峰与0级信号峰之间的微波频率差获得磁场大小,反之亦然,可以保持磁测数据连续不失锁,不需要外部磁场方向参考,首次实现了CPT原子磁力仪自主的全向测量能力.更多还原

【Abstract】 Omni-directional measurement of the geomagnetic field in satellites is necessary. Coherent population trapping(CPT)atomic magnetometer is theoretically capable of omni-directional measurement of magnetic fields, but it requires a reference signal in the direction of the magnetic field. To solve this problem, a new control method was proposed in this paper to trap four CPT signals. First, the control system demodulates the CPT differential signals with n=–3, n=–2, n=+2,and n=+3 by a time-division frequency modulation. Second, these CPT differential signals are fused to obtain two new feedback signals: one feedback signal used to calibrate the central frequency between n=±2 or n=±3, and the other feedback signal used to adjust the frequency between the central frequency and the CPT signals with n=±2 or n=±3.When a change in the magnetic field direction causes CPT signals with n=±2 or ±3 to disappear, the two feedback signals remain unaffected. Therefore, this control method does not require a fluxgate magnetometer to provide the magnetic field direction for mode switching and can obtain continuous magnetic data without losing lock in the range of 0°–360°. This means that it is an autonomous omni-directional CPT atomic magnetometer.更多还原