AC vector magnetometers have recently become increasingly widespread. The calibration of AC vector magnetometers before use is critical. Based on traditional ellipsoid fitting, which is suitable for calibrating DC vector magnetometers, a method suitable for calibrating AC vector magnetometers is presented. Simulation analysis and experimental verification demonstrate that this method is effective in calibrating AC vector magnetometers, including scaling factors, angular misalignments and offset errors.

Deep dielectric charging/discharging is a serious space environmental effect. Charging electric fields are the fundamental cause of dielectric discharging. In order to quantitatively mitigate deep dielectric charging effects, the GEANT4 toolkit and radiation-induced conductivity model were used to calculate the maximum possible internal charging potential and electric field with different shielding layer thicknesses, dielectric thicknesses, and ground types. The study selected electron spectra from geostationary earth orbit (GEO) and jupiter orbits as the input environment. With these calculations, a criterion for shielding, dielectric thickness, and ground types is provided such that spacecraft engineers may choose the appropriate method to decrease the deep dielectric charging effects. The charging time constants of flame retardant 4 and polytetrafluoroethylene are ~20 and 500 h, respectively, with a little dependence on input electron spectra, ground type, shield thickness, or dielectric thickness. The dielectric characteristics, ground types, and thicknesses, which can significantly change the value of the electric field, are critical for preventing deep dielectric charging. The maximum saturation charging potential and electric field at jupiter orbit are much larger than those at GEO.

The Medium‐Energy Electron Detector (MEED), a space weather monitoring instrument on the Fengyun‐3E (FY‐3E) satellite, is introduced in this paper. The MEED utilizes pin‐hole imaging technology on low‐orbit satellites for medium‐energy electron detection. Two orthogonal sensor heads enable the MEED to measure electrons from 18 directions simultaneously in the energy range of 30–600 keV (divided into eight exponentially distributed energy channels). The instrument has a ∼12° angular resolution and covers two 180° × 30° fields of view. With the magnetometer onboard the same satellite, the pitch angle distribution of medium‐energy electrons can be obtained with good angular resolution. This paper presents the design principle, ground calibration results, and preliminary on‐orbit test results of the FY‐3E MEED. The on‐orbit test results show that the medium‐energy electron fluxes, geographical distribution, energy spectrum, and pitch angle observed by the MEED are in agreement with the expected results. The MEED provides a new method to observe the low‐orbit energetic electron radiation environment from the FY‐3E satellite. Its successful in‐orbit operation will enable the theoretical study of radiation belts and improve space weather research.

Magnetic sensor array has become increasingly widespread in use. Because of the manufacturing process, magnetic sensors in an array inevitably experience calibration factor errors. Therefore, the calibration of a magnetic sensor array is very important before use. However, it lacks explicit and quantitative measures on how to calibrate a magnetic sensor array. By using magnetic fields produced by a standard magnetic source at different locations, a practicable method was proposed based on the least-squares method to calibrate a magnetic sensor array. The dimensions of sensor array are about 50×50×50 cm ³ and the level of magnetic field aiming to be measured is ~nT. Both the simulation and experimental results demonstrate that the proposed method is effective in identifying the calibration factor of a magnetic sensor array.

a deep dielectric charging effects monitor was proposed for providing in-situ measurements of deep dielectric charging effects on satellites via measurements of the surface leakage currents and the internal charging potential of the dielectric. The detailed design and the first flight results onboard a medium earth orbit (MEO) navigation satellite was discussed. Large temporal variations of the leakage currents were observed in the outer zone. The first flight data showed that the maximum charging electric field of the FR4 dielectric was less than 1.5×10 4 V/m, and the incident internal flux was less than 100pA/m2, and no charging risk was determined in this period. The calculated conductivity of the FR4 dielectric was about 1.4–3.7×10 -15S/m. These results showed that conductivity obtained by the traditional method overestimated the true value, whereas that obtained by the charge decay method underestimated the true value.

The internal charging effect may lead to electrostatic discharges (ESDs) for Geostationary Earth Orbit (GEO) and Middle Earth Orbit (MEO) satellites. This is due to the high-energy electrons that deposit in the dielectrics of satellites. The properties of the dielectrics such as permittivity and dark conductivity dominate this effect. This may contribute to the ESD risk of long-lifetime satellites if these properties change with the increase of electron dose. Two general materials, Polyimide (PI) and FR4 Epoxy Glass Cloth (FR4), were chosen as samples to study by experiments with different doses. The results show that the permittivity of PI and FR4 decreased as the dose increased while the dark conductivity increased. Numerical simulation evaluates the electron dose and the ESD risk of dielectrics under the electron environment of a specific MEO electron spectrum. The results show that the decrease of permittivity and the increase of dark conductivity will shorten the time constant of internal charging. The quicker build-up of electric field will increase the ESD risk if it exceeds the breakdown threshold.