Double-probe spaceborne electric field sensor for earthquake precursor detection in ionosphere

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Double-probe spaceborne electric field sensor for earthquake precursor detection in ionosphere

Chen, Xian-xiang / Ren, Ren / Yang, Ji / Fang, Dong-min / Xia, Shan-hong

Electric field abnormal is one of the most important earthquake precursor phenomena in the ionosphere. The ionosphere electric field abnormal has the characteristic of wide frequency band (frequency range from DC to several MHz), which is suitable to be detected by the double-probe spaceborne electric field sensor (DSEFS). The DSEFS is composed of four sensing probes, four booms outside of the satellite and one signal acquisition and processing system (SAPS) inside the satellite. The four booms are used to set the four probes away form the satellite platform and form a tetrahedron in the space. The plasma potential around the probe is coupled to the probe though equivalent resistor and capacitor in parallel, which is the result of the probe charging. The plasma potential is acquired with a preamplifier with very high input impedance in the probe. In order to insure the detection precision, the value of equivalent resistor can be adjusted with a bias current provided by the SAPS. The probe potential is further acquired and processed by the SAPS to form three dimensional orthogonal electric field detection results. In order to insure the detection precision of the plasma electric field, the Spacecraft and Plasma Interaction System (SPIS) simulation software was used to simulate the interaction between satellite, sensor probes, booms and surrounding plasma. There are two major contributions in the paper. Firstly the layout of the sensor probes outside the satellite was optimized to reduce the influence of wake effect. Secondly, the fixing mode between the boom and satellite was optimized to reduce the influence of satellite potential change on the probe charging characteristic.