| Since Cluster II mission, more and more multi-point measurement missions have been developed in recent years. Compared with the traditional single-point measurement, the multi-point measurement has advantage in measuring the multi-point magnetic field synchronously, eliminating the temporal change in the magnetic field, and obtaining information without a temporal-spatial coupling, which is helpful for the study of space magnetic field and plasma. However, there are no small-scale, multi-point measurement missions yet, which can obtain the fine structure of the local magnetic field. For instance, the combination of Cluster II and Double Star cannot do a good measurement of the small-scale processes, and the large-scale of THEMIS is also not suitable for studying the fine structures of magnetic field and current density.The article tries to prove the feasibility of a multi-point, multi-scale and synchronous measurement, according to the small-scale and multi-point network of one master payload and four separated payloads. The main work of the article is to verify the possibilities of inverting the current density and the orientation, geometrical structure and motion of the magnetic field structure, with 5-points synchronous magnetic field measurements. We also analyze the error in the current density inversion, focusing on determining the main error source and proposing several suggestions for actual detections. The results are as follows.Some numerical simulations have been done, based on the current density inversion method for the multi-point magnetic field measurements, to analyze the affecting factors of the space current density inversion. It is found that 5-point measurements are better than 4-point measurements, whose errors mainly come from the satellite attitude measuring error and the external magnetic field intensity. Besides, the formation configuration of the satellites is also an important factor. According to the simulation, the maximum error in current density is less than 24% near the equator when the attitude determination error is 0.001°and the scale of the satellite formation is about 100 km. A proper formation configuration is essential when the external magnetic field is strong.Besides, inversion of orientation and motion of one-dimensional magnetic field and geometrical structure of magnetic field with multi-point synchronous magnetic field measurements can get good results even when there is little measurement errors. The methods can be used in a practical calculation. |
