The PEPSO plasma chamber: a laboratory tool to design, test and validate space plasma experiments

This contribution focuses on the PEPSO (Plasma Environment Platform for Satellite tests in Orlans) plasma chamber facility, hosted at the LPC2E Laboratory in Orlans, France, since 2020, as well as specific examples of how it is being used for the design of planetary and cometary space plasma experiments.PEPSO is designed to provide a test environment that mimics the plasma environment in terrestrial, planetary or cometary ionospheric regions. It is composed of a 1.8m long and 1m wide cylindrical vacuum chamber, a pumping system, a plasma source, and a flexible set of sensors. The vacuum chamber has a form factor that is compatible with the study of the behavior of objects of limited size, such as nanosatellites, payload or specific sensors. The pumping system creates the conditions for the use of the plasma source. The plasma source ensures the creation of a plasma with characteristics similar to Earth ionospheric plasma. Various diagnostics are used to monitor the plasma characteristics and therefore provide feedback on the current state of the plasma.PEPSO has been recently used to perform mutual impedance experiments. Mutual impedance instruments are an active, in situ space plasma diagnostic dedicated to the measurements of electrons. They rely on two electric antennas, one of them is used to generate an electric perturbation inside the plasma, while the other one measures such perturbation. The propagation characteristics of the perturbation provides insight into the plasma properties. They are part of the scientific payload of past, current, and future space missions. Such missions include the joint ESA/JAXA BepiColombo, that targets Mercury, the ESA JUICE, that targets Jupiter and its moons, the ESA Comet Interceptor, that targets a pristine comet, and the M-MATISSE mission project that targets space weather studies at Mars.In our contribution, we will illustrate how the PEPSO facility has been used, e.g., for the design of the COMPLIMENT (COMetary Plasma Light InstruMENT) of the ESA Comet Interceptor mission, for the design of the COMPASS/MIX experiment for the M-MATISSE mission project, as well as to support the CNES-funded COMIX (COmpact Mutual Impedance eXperiment) RT project.In particular, we will focus on the development of new instrumental techniques that improve the mutual impedance time resolution up to a factor 20. We will show how numerical models of the instrument are tested in the controlled environment of a laboratory experiment by comparing their predictions to the measurements. This enables the use of such numerical models to obtain a plasma diagnostic from embarked instrument.