Abstract
This paper reports the design, calibration, and operation of high-energy electron experiments (HEP) aboard the exploration of energization and radiation in geospace (ERG) satellite. HEP detects 70 keV–2 MeV electrons and generates a three-dimensional velocity distribution for these electrons in every period of the satellite’s rotation. Electrons are detected by two instruments, namely HEP-L and HEP-H, which differ in their geometric factor (G-factor) and range of energies they detect. HEP-L detects 70 keV–1 MeV electrons and its G-factor is 9.3 × 10−4 cm2 sr at maximum, while HEP-H observes 0.7–2 MeV electrons and its G-factor is 9.3 × 10−3 cm2 sr at maximum. The instruments utilize silicon strip detectors and application-specific integrated circuits to readout the incident charge signal from each strip. Before the launch, we calibrated the detectors by measuring the energy spectra of all strips using γ-ray sources. To evaluate the overall performance of the HEP instruments, we measured the energy spectra and angular responses with electron beams. After HEP was first put into operation, on February 2, 2017, it was demonstrated that the instruments performed normally. HEP began its exploratory observations with regard to energization and radiation in geospace in late March 2017. The initial results of the in-orbit observations are introduced briefly in this paper.
Highlights
The mechanisms by which electrons are accelerated in geospace are a key research area in solar-terrestrial plasma physics
This paper describes the design of the high-energy electron experiments (HEP) instruments, prelaunch testing, and initial results of the inorbit observations
The SSD modules in HEP-L and HEP-H are independently controlled by two control boards that include field programmable gate arrays (FPGAs) and point-of-load (POL) DC–DC converters to power the application-specific integrated circuits (ASICs)
Summary
The mechanisms by which electrons are accelerated in geospace are a key research area in solar-terrestrial plasma physics. The high-energy electron experiments (HEP) onboard the ERG satellite detects 70 keV–2 MeV electrons and generates a three-dimensional velocity distribution of electrons for every period of the satellite’s spin. HEP-L observes 70 keV–1.0 MeV electrons, and the G-factor of its three detector modules is 9.3 × 10−4 cm2 sr.
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