Numerical Confirmation of the Dramatically Reduced Secondary Electron Emission Yield of Velvet-like Surfaces

Recent experimentation with Hall Thrusters [1] has shown that the effective secondary electron emission yield of Hall Thruster walls is dramatically reduced by application of velvet-like fibers to the walls. This secondary electron emission suppression is presumably due to re-collision of secondary electrons with the fibers before emitted electrons can return to plasma. A numerical evolution of the resulting electron velocity distribution function of emitted electrons returning to the plasma was performed for this surface geometry; and the results were benchmarked against analytic calculations and experimental findings. \\[4pt] [1] Y. Raitses et. al., IEEE Trans. Plasma Sci. \textbf{39}, 995 (2011).