Evaluation of the Proton Contamination to MeV Electrons by Solar Proton Events Based on CSES Observations

The high energy particle package (HEPP) onboard the China Seismo‐Electromagnetic Satellite (CSES) consists of three subsystems: HEPP‐H, HEPP‐L, and HEPP‐X. HEPP‐H and HEPP‐L detect 0.1–55 MeV electrons and 2–230 MeV protons. HEPP‐X is used to monitor 0.9–35 keV solar X‐rays. The primary objective of this study is to present the measurement techniques and instrument parameters, show the main features of particle observations recorded by these instruments and evaluate the proton contamination to MeV electrons. Based on CSES observation, we report a typical solar X‐ray and solar proton event and compare with observations from Polar Orbiting Environmental Satellites (POES) and Geostationary Operational Environmental Satellites (GOES) satellite. Based on the observations of solar proton events, we put forward one method to evaluate the proton contamination level using comparatively pure proton samples on high L‐shells where the proton flux is near zero at quiet time. The percentage of protons that are mistakenly identified to be electrons by HEPP‐H is estimated to be approximately 0.022%. The proton contaminations only contribute no more than 10% of the total observed electron populations at L = 4 with energy range 8–9 MeV in the outer radiation belt region. Therefore, we conclude that the on‐orbit performance of HEPP instrument has satisfyingly met the design expectations by providing plenty of high‐quality high energy particle observation data and reference for scientific uses in the fields of space weather research and natural hazard monitoring. Key Points Measurement techniques and instrument parameters are presented for the high energy particle package onboard China Seismo‐Electromagnetic Satellite (CSES) satellite A typical solar X‐ray and solar proton event are reported based on CSES, Polar Orbiting Environmental Satellites (POES), and Geostationary Operational Environmental Satellites (GOES) observations The proton contamination level to MeV electron measurements is evaluated