In order to meet the needs of ionospheric research and monitoring of space station charging, the technology of plasma in-situ imaging detection is studied. The plasma in-situ imaging detector is one of the first outside scientific payloads of the Chinese space station to detect the space environment. It is installed on the extravehicular platform of the Wentian module, and will carry out multi-element comprehensive detection of ionospheric plasma, including in-situ, imaging, and charging potential. The refined detection data of the low latitude ionosphere will provide plasma parameters for improving the orbital ionospheric model of the space station. And the long-term charging potential data are collected to support the studying of the charging effect of plasma on the space station and promoting the establishment of the space station charging evaluation system.

The plasma in-situ imaging detector integrates Langmuir probe, retarding potential analyzer, ion drift meter, reference potentiometer, ion imaging technology, etc. Electron density and electron temperature are measured by Langmuir probe. Ion composition,ion density,ion temperature, and ion drift velocity are measured by retarding potential analyzer and ion drift meter. The ion imaging parameters are obtained by ion imager. The reference potential sensor is available to provide the measurements of charging potential of Wentian module. The Langmuir probe sensor inherits the design of the Langmuir probe sensor of CSES (Zhangheng-1 satellite). The retarding potential analyzer and ion drift meter also inherit the design of CSES (Zhangheng-1 satellite), and improve the design of grid voltage and collector voltage which can be adjusted adaptively according to on orbit state. The ion imager consists of an electrostatic deflection module, a Whalen analyzer and an imaging module. The ion imaging technology is for the first time applied to the field of space environment detection in China.

The plasma in-situ imaging detector is tested and calibrated to verify the performance at the National Space Science Center of the Chinese Academy of Sciences. when this paper is submitted, the detector mounted on Wentian module has been successfully launched. Next, the detector will be assembled by astronauts inside the capsule using external interfaces . Then, the detector will be grabbed by the robotic arm and installed on the extravehicular experimental platform to start a long-term exploration mission.