Anisotropic molecular scattering at microstructured surface for rarefied gas compression inside air breathing ion engine

The effect of the micro-structure surface on the passive compression performance of the intake system of an air-breathing ion engine (ABIE) system is proposed and analysed. The scattering distributions of the thermal Ar beam pulses at the microstructure surface were measured experimentally. The scattering process at the microstructure surface demonstrated anisotropic nature at a grazing angle of incidence; however, it demonstrated a complex scattering pattern due to the multiple bounce effect at the facet surface, despite each scattering pattern being similar to that on the flat surface. The DSMC calculation at an altitude of 250 km was also performed using the simple scattering model, which is based on the experimental results of scattering distribution and recent ABIE design. The computational results indicate that the compression performance of the microstructure intake is higher than that of the diffusive and specular flat intakes.