基于行星际磁场阿尔芬特性的星载磁通门磁强计在轨标定新方法

A new method for in-flight calibration of spaceborne fluxgate magnetometers based on Alfvénic nature of the interplanetary magnetic field

准确的磁场测量对深入研究空间等离子体环境具有重要意义.星载磁通门磁强计的磁补偿随时间缓慢变化,因此,需要对其进行常规的在轨标定.现有的在轨标定方法都依赖于磁扰动或磁结构事件的筛选,导致标定结果的频次受限于事件的筛选,且差的事件还会增大计算误差.为此,本文研发出一种不依赖于磁场事件筛选的在轨标定新方法.根据行星际磁场强度的取值范围,我们可建构一个磁补偿取值空间.不同的磁补偿值会影响行星际磁场的阿尔芬特性;于是,我们通过在磁补偿空间中找到使被调整之后的行星际磁场的阿尔芬特性最强的点作为磁补偿值的最优解.测试结果表明,我们的新方法可以利用1~4 h时长的行星际磁场数据获得误差小于0.1 nT的标定结果.

Accurate magnetic field measurements are the key to an in-depth study of the space plasma environment.The zero offset of the spaceborne fluxgate magnetometer changes slowly with time,therefore,it needs to be calibrated regularly.All the previous in-flight calibration methods rely on the selection of magnetic fluctuation or structure events,resulting in that the frequency of the calibration results is limited by the selection of events,and poor events will also increase calculation errors.To this end,a new in-flight calibration method that does not rely on the selection of the magnetic field events is developed in this paper.According to the possible range of the interplanetary magnetic field strength,we can construct a value space of the zero offset.Different zero offset values will affect the Alfvénic nature of the modified interplanetary magnetic field;therefore,the point is found to be the zero offset so that the Alfvénic nature of the modified interplanetary magnetic field is the strongest.The test results show that our new method can obtain zero offset with an error of less than 0.1 nT using 1~4 h of the interplanetary magnetic field data.