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

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 Alfvenic nature of the modified interplanetary magnetic field; therefore, the point is found to be the zero offset so that the Alfvenic 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.