Design and Implementation of a Langmuir Probe Instrument for the ROMEO Satellite

Plasma diagnostics are methods and instruments that serve to measure different properties of plasma, such as electron and ion distribution functions. Due to being easy to construct, Langmuir probes are often used for conducting plasma diagnostics. From spherical to cylindrical, they can have a variety of shapes. They work by using one or more electrodes that are inserted into plasma and are biased by a constant or time-varying voltage with respect to the plasma potential. Electrical currents can be measured this way to determine plasma parameters and obtain its current-voltage characteristic. This thesis focuses on the prototype circuit board of a Langmuir probe system that was designed for two spherical probes with the dimension of 2 cm in radius.
The final Langmuir probe instrument will be carried by the ROMEO (Research and Observation in Medium Earth Orbit) satellite, currently being developed by the University of Stuttgart Institute of Space Systems. The target of the mission is the plasma dominant Medium Earth Orbit (MEO) region with harsh radiation environment, due to the high-energetic particles trapped in the Van Allen belts. The primary goal is to operate in the lower MEO regimes, as utilizing MEO would enable to reduce the growing number of spacecrafts in the more radiation protected Low Earth Orbits. The satellite will reach an elliptical orbit of 330 x 2500 km.
The measurement device is a mixed-signal electronics containing an analog and a digital circuit section. The measurement ranges used for designing the system were calculated based on the orbit requirements and expected plasma parameters. The degree project describes the design choices, implementation and testing of the prototype, with further development suggestions for the final flight version.