The electronics of the High-Energy Particle Detector on board the CSES-01 satellite

CSES (China Seismo-Electromagnetic Satellite) is a Chinese-Italian scientific space mission dedicated to monitor the variations of the main parameters of the topside ionosphere (electric and magnetic fields, plasma parameters, charge particles fluxes) caused by either natural emitters - especially earthquakes - or artificial ones. The CSES satellite was successfully launched from the Jiuquan Satellite Launch Center located in the west of Inner Mongolia on February 2nd, 2018, and it is now orbiting under nominal conditions. The expected mission lifetime amounts to 5 years. CSES is the first element of a multi-satellite monitoring system; several satellites are scheduled for the next few years. The High Energy Particle Detector (HEPD) is the main contribution of the Italian collaboration to the mission. It was designed and built in order to detect electrons in the energy range between 3 and 100 MeV, protons between 30 and 200 MeV, and light nuclei in the MeV energy window. The electronics of the detector was designed following stringent requirements on mechanical and thermal stability, power consumption, radiation hardness and double redundancy. The system successfully went through the space qualification tests. In this paper, we describe the HEPD electronics, the space qualification tests performed before launch, and the in-flight performance of the detector.