For the development of satellites with electric propulsion systems, confirming the operation of electric propulsion systems in the satellite system configuration is crucial. At the same time, understanding the impact of contamination caused by electric propulsion on the inner wall of vacuum chamber is important. In this research, to determine the effect of electric propulsion plasma beam exposure on the inner wall coating, the thermal control paint Aeroglaze®️ Z306 (Z306) is exposed to the ion thruster plasma beam. The sputtering rate of Z306 of generated particles are assessed using two quartz crystal microbalances (QCM): one is used to measure sputtering rate by coating one electrode of the QCM by Z306; another is used to collect the sputtered particles, named "Cryogenic-QCM (CQCM)."

 The electrode of Z306-coated-QCM is arranged vertically on the plasma beam axis for the sputtering rate measurement. On the other hand, for the particle collection, CQCM is positioned at an angle where its surface points towards the sputtered Z306 surface while the Z306 is exposed to the plasma beam. The ion thruster is operated at various acceleration voltages using Ar or Xe gas as the propellant. The frequency difference between the plasma-exposed electrode (det-electrode) and the non-exposed electrode (ref-electrode) in CQCM is monitored to evaluate sputtering and deposition.

The frequency differences decrease when the Z306 coated electrode is exposed to plasma. The decreasing speed of frequency difference, i.e., the sputtering rate, significantly increases as the acceleration voltage is raised from 500 to 1500 V for both Ar and Xe plasma. At an acceleration voltage of 1500 V, the sputtering rates of Z306 are 1.10 and 0.59 mm3/C for Ar and Xe plasma, respectively. In the presentation, we will discuss further results and analysis of contamination on CQCM including its amounts and chemical state by using FTIR and Raman spectroscopy.