Analysis and elimination of tri-band beacon interference with the fluxgate sensors onboard CSES

High precision magnetometer (HPM) is a magnetic field detection payload onboard China Seismo-Electromagnetic Satellite (CSES), including two fluxgate magnetometers (FGM) and a coupled dark state magnetometer (CDSM). Observations show that FGM appears to be influenced when tri-band beacon (TBB) is powered on and emits electromagnetic waves. The interference phenomenon is further validated based on both in-orbit observation analysis and electromagnetic compatibility (EMC) tests on the ground. A joint correction algorithm based on the least square fitting and first-order difference method according to scalar magnetometer data is proposed to eliminate the interference. The algorithm significantly improves the consistency of HPM data. After correction, the average scalar deviation error could be reduced from 9.0 nT to around 0.7 nT.