星载原子钟磁致频移影响在轨评估

On-orbit evaluation of influence of magnetic-induced frequency shift on space borne atomic clock

星载原子钟作为磁敏感设备,外界磁场变化会导致星载原子钟输出频率发生变化.本文采用星载主备原子钟比相法评估了10颗配置星载氢原子钟的MEO导航卫星原子钟频率稳定度,短期稳定度平均值优于1×10^(−12)τ^(−1/2),天稳均优于7×10^(−15).基于该稳定度水平,本文针对导航卫星原子钟磁致频移进行了初步评估,得到磁力矩器工作情况下原子钟磁致频移达到1×10^(−13)量级,磁力矩器持续工作1 h将引起钟差预报误差0.4 ns.本文将在轨磁力矩器工作状态等效为磁致频移噪声,仿真分析了其对星载原子钟稳定度的影响,仿真结果表明,该磁致频移噪声将恶化星载原子钟长期稳定度,尤其对稳定度更高的原子钟恶化更明显.本文最后就如何降低磁致频移对星载原子钟的影响进行了讨论.

The output frequency of an on-board atomic clock changes with a change in the external magnetic field as it is a magnetic sensitive device.In this paper,the phase comparison method is employed for the main and standby atomic clocks to evaluate the frequency stability of 10 Medium Earth Orbit(MEO for short)navigation satellite atomic clocks equipped with hydrogen atomic clocks.The average short-term stability is higher than 1×10^(−12)τ^(−1/2),and the daily stability is higher than 7×10^(−15).Based on this stability level,this paper presents a preliminary evaluation of the magnetic frequency shift in the atomic clock in the navigation satellite.The magnetorquer can cause a shift in the magnetic frequency of the atomic clock to an order of 1×10^(−13).In addition,the continuous operation of the magnetic torque converter for 1 h will cause the prediction error of the clock difference to be 0.4 ns.In this paper,the working state of the on-orbit magnetorquer is equivalent to the magnetic frequency shift noise,and its influence on the stability of the on-board atomic clock is simulated and analyzed.The simulation results show that the magnetic frequency shift noise worsens the long-term stability of the on-board atomic clock,especially for those with higher stability.Furthermore,the possible ways of minimizing the effect of the magnetic frequency shift on the atomic clock are discussed.