## 1 Introduction
[18] revealed the global distribution of ionospheric ELF/VLF wave intensities and energetic electron precipitations during an intense magnetic storm by making use of DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) observations (altitude: \(\sim\)710 km in 2004), and a good correlation between waves and particle precipitations at different stages of storm evolution was revealed. Still relying on DEMETER observations, [PERSON] et al. [9] statistically analyzed the temporal-spatial variations of the ionospheric ELF/VLF waves during all the intense CME-driven storms that occurred from 2005 to 2009 (altitude: \(\sim\)660 km), specifically showinghow the ELF/VLF waves in different frequency ranges were excited across the \(L\) shell space during the evolution of this type of storms. Since the successful operation of the French DEMETER satellite (2005-2010), which was mainly dedicated to the investigation of ionospheric disturbances possibly associated with the strong earthquakes, volcanoes, or anthropogenic activities from the lithosphere ([PERSON] et al., 2018), a growing number of studies ([PERSON] et al., 2018; [PERSON] et al., 2018; [PERSON] et al., 2018) obtained from DEMETER observations have been suggesting that satellites probing electromagnetism in LEO space can be regarded as promising tools to monitor natural hazards ([PERSON] et al., 2018). However, since DEMETER was decommissioned in December 2010, there lacks similar type of electromagnetic satellite in the ionosphere to provide first-hand observations for studying natural disasters until the recent successful launch of the CSES on 2 February 2018 at an altitude of 507 km in the ionosphere ([PERSON] et al., 2018; [PERSON] et al., 2018). The CSES is part of China's Zhangheng mission, which is aimed to launch both electromagnetic and gravity satellites in near-Earth orbit within the next few decades. The Zhangheng mission is named after the ancient scientist [PERSON] who invented the world's first seismoscope in the second century CE. The Zhangheng-01 (ZH-1) mission is dedicated to the electromagnetic satellites with three planned consecutive launches--it is also known as the CSES; Zhangheng-02, in the preparation phase at present, is dedicated to gravity satellites. The first probe of the CSES mission was successfully launched into a sun-synchronous circular orbit. The second probe will be launched into the same orbit before December 2022, but it will operate at the opposite side of the Earth, which means that two probes will be operating on both the day and night sides of the ionosphere by 2023 (the first probe was designed to span a five-year lifetime but is expected to operate longer). Since its successful launch in 2018, the CSES has been providing valuable measurements about the electromagnetic field across a broad frequency range from ultra-low frequency (ULF) to very low frequency (VLF), and even to the high frequency (HF) of the electric field, as well as fluxes of energetic electrons at energies from 0.1 to 50 MeV. In view of the importance of electromagnetic wave activities and energetic electron populations for natural hazard science, the purpose of this paper was to investigate the features of waves and particles in LEO space by using CSES observations. Based on previous DEMETER studies ([PERSON] et al., 2018; [PERSON] et al., 2018) (at altitudes from -660 to 710 km), this work presents CSES data to describe the temporal and spatial distribution of the ionospheric ELF/VLF waves and energetic particle fluxes during the G3-class storm (Dst minimum of -174 nT) that occurred on 26 August 2018. A brief introduction to the CSES and associated payloads is provided in Section 2, while the distributions of ionospheric ELF/VLF waves and energetic electron fluxes are presented in Section 3. Section 4 offers a discussion concerning experimental observations, and Section 5 briefly summarizes the main results.