Effects of space plasma on an oxide coating of spacecraft's surface materials

The aim of this paper is to study the properties of the materials for spacecraft surfaces under the effects of simulated low Earth orbit (LEO) plasma environment to understand the effects of charging and discharging phenomena, which are known to take place when spacecraft is moving through space plasma in LEO. Anodized aluminum Al2O3 samples were prepared using electrochemical techniques with different thicknesses to investigate the role of the Al2O3 coating in the charging and discharging phenomena. Penning plasma source is used to generate plasma using Ar gas flowing through the vacuum chamber. The peak current and the voltage waveform associated with charging and discharging processes, when a negatively biased voltage is applied to the substrate, are discussed. The structural properties before and after plasma exposure are investigated through the morphology and optical analyses of the samples. Morphological analyses confirmed the significant contribution of space plasma in the variation of the crystalline structure, and sample characteristics are dependent on the value of the thickness. In addition, the results confirm the variation of optical properties and the microcrystalline structure over the surface of the anodic oxide film.