阿尔芬波总磁场存在漂移趋势时磁通门磁强计在轨标定的优化方法

An optimal method for in-flight calibration of the fluxgate magnetometer when the total magnetic field of Alfvén waves has a drift trend

高精度的磁场测量对深空探测具有重要意义,然而卫星上磁通门磁强计的磁补偿值会随着时间缓慢变化,需要进行在轨标定.近期,一种新的在轨标定方法被提出,即Wang-Pan方法.该方法发现阿尔芬波动存在一个线性度高的最优补偿曲线,利用多个波动的最优补偿曲线可计算出磁强计的磁补偿.然而,该方法没有考虑所选波动事件的总磁场存在漂移趋势的情况.本文通过数值分析,发现阿尔芬波总磁场存在漂移趋势时最优补偿曲线会偏离真实的磁补偿值,甚至不再具有较高的线性度,从而产生计算误差;将该漂移趋势去除之后,可显著降低Wang-Pan方法的计算误差.我们利用金星快车的磁场数据验证了该优化方案的可行性.本文的研究成果有助于将Wang-Pan方法应用于地球磁层卫星.

High-precision magnetic field measurement is of great significance for deep space exploration.However,the zero offset of the fluxgate magnetometer on the satellite will change slowly with time,which requires in-flight calibration.Recently,a new in-flight calibration method has been proposed,namely the Wang-Pan method.It is found that there is an optimal offset line with a high linearity in the offset cube for an Alfvén wave,and the zero offset of magnetometer can be calculated by using the optimal offset lines of several Alfvén waves.However,this method does not take into account the drifting tendency of the total magnetic field of the selected events.Based on numerical analysis,we found that the optimal offset line will be far away from the real zero offset and even no longer has a high linearity if the total magnetic field of the Alfvén wave has a drift trend,which results in calculation errors.Nevertheless,the calculation error of the Wang-Pan method can be significantly reduced after removing such a drift trend.We verify this optimal method by using the magnetic field data obtained from the Venus Express.The results of this paper will be helpful for the application of the Wang-Pan method to the terrestrial magnetospheric satellites.