부산대학교 도서관

In has been confirmed that a turbo-molecular pump (TMP) coated with SiO_2 gives a higher compression ratio than a non-coated pump by a previous experiment. In order to investigate the effect of the surface roughness on the pumpling performance, the surface roughness was modeled by statistically located circular cone peaks and dimples of the same base radius and various base angle. The actual surface roughness of the blade was measured by SEM, and then the obtained angle distribution was used for the roughness model. The 3D Monte Carlo simulation for SiO_2 coated TMP was done using the proposed surface roughness model. The calculated maximum-compression ratio was compared with the previously measured values and 2D calculated results. The present results showed almost the same values as the experimental ones, and agree well with the 2D calculated results.