Experimental Characterization and Simulation-Based Analysis of the RIT-2.5 Radiofrequency Ion Thruster

We report on the experimental characterization of the RIT-2.5 radiofrequency ion thruster, complemented by particle-in-cell (PIC) simulations to establish correlations between plasma parameters and extracted beam properties. The thruster was operated in a dedicated vacuum facility and equipped with optical spectroscopy, Faraday cup, and retarding field energy analyzer (RFEA) diagnostics. Electron temperature was determined from optical emission line ratios (Te about 3-7 eV), while the energy distribution of extracted ions was measured using the RFEA. A comparative simulation campaign was performed to reproduce the experimentally observed energy spectra and to extract plasma density values otherwise inaccessible due to the lack of intrusive diagnostics, yielding best-fit estimates of ne about 1.2x10E16 m-3. The results demonstrate that the energy spread of the extracted beam is strongly dependent on plasma density and electron temperature. The combined experimental-numerical approach provides a non-intrusive yet robust pathway for performance optimization of RF ion thrusters, offers validation benchmarks for advanced plasma simulation codes, and is particularly well-suited to compact micro-N-class thrusters for nanosatellite attitude and orbit control.