Proba 2 Thermal Plasma Measurement Unit (TPMU)

The PROBA-2 Thermal Plasma Measurement Unit was developed by a Czech consortium, led by the Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic. The TMPU comprises a sensor unit, which consists of the probes and their preamplifiers, and a processing unit. TPMU’s objective is study the ionosphere, its dynamics, and response to solar and geomagnetic activity. It measures the total ion density and electron temperature, the ion composition and ion temperature, and the floating potential of the satellite body.

The electron temperature measurement is based on the radio frequency probe technique using the RF signal (∼50 kHz) modulated by the square wave. It uses three simple circular planar probes with guard rings. A constant voltage shift is maintained by applying the proper amplitude of the radio frequency signal. The probe potential is periodically scanned and adjusted for minimum electron temperature.

The ion measurement, based on the RPA (Retarding Potential Analyzer) technique, can work in two modes. The first mode measures the ion flux at plasma potential. The second mode is the measurement of volt-ampere retarding characteristics. This uses an analysing voltage sweep which can be selected in the range 0 V to 20 V. Individual measurements are time-stamped and can be related to the satellite onboard time and thus orbital position. The fields of view of the TPMU sensors are aligned with the flight direction of the satellite as far as is allowed by the Sun-pointing attitude. TPMU shares some interface, power and processing resources with DSLP.

PROBA-2热等离子体测量单元由捷克共和国科学院大气物理研究所领导的一支捷克联盟研发而成。该TMPU包括一个传感器单元，由探头及其前置放大器组成，以及一个处理单元。TMPU的目标是研究电离层及其动力学特性，以及对太阳活动和地磁活动的响应。它测量了总离子密度和电子温度、离子成分和离子温度，以及卫星本体上的浮电位。电子温度的测量基于射频探头技术，使用射频信号（约50 kHz）通过方波进行调制。它采用三个简单的圆形平面探头，配备保护环。通过应用适当的射频信号幅度，维持一个恒定的电压偏移。探头电位被周期性地扫描并调整至最小电子温度。离子测量基于RPA（延迟电位分析仪）技术，可以工作在两种模式。第一种模式测量等离子体电位处的离子通量。第二种模式是测量伏安延迟特性。这使用一个分析电压扫描，可在0 V至20 V的范围内选择。个别测量被标记了时间戳，可以与卫星机载时间以及因此确定的轨道位置相对应。TPMU传感器的视场与卫星的飞行方向对齐，尽可能与太阳指向姿态相符合。TPMU与DSLP共享一些接口、电源和处理资源。