China seismo-electromagnetic satellite (CSES) is launched to detect the electromagnetic environment in space for the study of seismic early warning. Langmuir probe is one of the payloads of the CSES satellite, and it is the first time that the Langmuir probe technique has been used in the Chinese satellite. The use of the Langmuir probe is to measure the space plasma parameters, such as electron density (Ne), electron temperature (Te), and to identify the instantaneous change of the space plasma. The Langmuir probe payload is composed of three parts, i.e., two sensors, two rods, and one electronics box. The sensor is installed at the top of the rod to extend out of the satellite surface, and is parallel to the direction of the satellite orbit. The electronics box is installed inside the satellite which includes the sweep voltage circuit, sensor signal circuit, DPU control and processing circuit, the satellite interface circuit, power supply circuit, etc. The sensor is spherical. Its upper hemisphere is a collecting electrode, and its lower hemisphere is a protective electrode. The same sweep voltage is applied to the upper hemisphere and the lower one which can eliminate the terminal effect of the connecting point between the traditional spherical structure and the rod. The diameters of the two sensors are respectively 50 and 10 mm, and the surface areas of the two sensors are respectively 1/2000 and 1/13000 times the satellite surface area. The stability of the satellite ground potential is not affected by the sweep voltages on the sensors. In addition, TiN material is coated on the sensor surface to ensure a uniform surface work function, and to prevent the space atomic oxygen erosion. The decontamination function is designed for the Langmuir probe to eliminate the possible pollution on the orbit. A positive 100 V voltage is applied to the sensor to accelerate electrons to bombard the sensor surface, thereby removing the contamination from the sensor surface. The advantage of the electron bombardment effect is that the TiN film is not damaged, meanwhile the positive 100 V voltage has high reliability and safety on orbit. The decontamination function has been proved to be effective by the test in Italy National Institute for Astrophysics-Institute for Space Astrophysics and Planetology (INAF-IAPS). The plasma environment calibration test of the Langmuir probe is carried out in INAF-IAPS. We measure the electron density and temperature at three different distances from the plasma source, and compare the results with the measured results of the INAF-IAPS reference Langmuir probe. Results show that the test data of our Langmuir probe are consistent with the INAF-IAPS reference data. Our Langmuir probe design is proved to be feasible to achieve the missions of the satellite.

From August to October 2018, a series of strong earthquake (EQ) events occurred in southeast Asia and northern Oceania (22°S to 0°N, 115°E to 170°E) within 50 days. In this paper, we analyze the features of ionospheric plasma perturbations, recorded by the Plasma Analyzer Package (PAP) and Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES-01), before four EQs with magnitudes of Ms 6.9 to Ms 7.4. The ion parameters such as the oxygen ion density (No⁺), the ion drift velocity in the vertical direction (V_z) under the conditions of geomagnetic storms, and strong EQs are compared. The results show that within 1 to 15 days before the strong EQs, the No⁺ and the electron density (Ne) increased while the electron temperature (Te) decreased synchronously. Meanwhile, the V_z significantly increased along the ground-to-space direction. The relative variation of No⁺ and V_z before the strong EQs is more prominent, and the V_z is not easily influenced by the geomagnetic storm but is susceptible to the seismic activities. Our results suggest that the anomaly of ionospheric plasma perturbations occurring in this area is possibly related to the pre-EQ signatures.

等离子体原位成像探测器是中国空间站的第一批舱外空间环境科学载荷，安装在问天舱的舱外暴露平台，将首次在空间站平台上开展电离层等离子体原位、成像、充电电位等多要素综合探测任务。其中，原位探测要素包括空间站轨道等离子体的密度、温度以及问天舱表面电位强度等。成像探测要素包括离子能量、运动方向和成像时间分辨率等。等离子体原位成像探测器采用多传感器的一体化设计，集成了朗缪尔探针、阻滞势分析仪、参考电位计和离子成像仪等技术。其中，离子成像技术是首次应用于我国的空间环境探测领域。等离子体原位成像探测技术在中国科学院国家空间科学中心定标实验室完成了测试验证，探测器已随问天舱成功发射，即将开展中低纬电离层的精细化探测，为完善空间站轨道电离层模型提供等离子体探测数据。通过探测累积长周期的充电电位数据，为研究等离子体对空间站的充电效应，促进空间站充电评估体系的建立提供支持。

针对可移动非接触式月球表面电位探测器的电位无扰动测量单元对低能远焦电子束的需求，设计了低能远焦电子枪。以平板二极管电子枪为电子源，匹配两个静电聚焦透镜，将电子源引出的发散电子束聚焦为需要的形状，并加速至所需能量。优化电子枪的几何参数以及施加在电极上的电位，电子枪引出的电子束能量在5~500 eV内，并且具有良好的电子光路特性。电子束能量为5 eV时，初始半径r为5 mm，束腰至电子枪出口的距离p约为133 mm。随着能量增加，r逐渐减小至500 eV时的3 mm左右，p逐渐减小至105 mm。电子束经月球表面电场反射被电子收集平极接收，仿真数据和理论分析结果均表明，电子枪的工作距离为400~600 mm，平板接收的电子占发射电子比例在96%以上。电子枪结构质量仅408 g，满足探测器对电子枪的质量需求。

研究讨论了一种利用半导体二极管伏安特性进行朗缪尔探针性能测试的方法. 设计的朗缪尔探针性能测试方法对外界因素要求较低,在常温常压的通常实 验室环境下即可进行,其测试结果可作为利用地面等离子体环境进行定标测试 前的初步性能验证. 通过实验室环境下的测试试验, 验证了该方法的有效性和 可行性.