Using Plucker coordinates for pumping speed evaluation of molecular pump in the DSMC method

摘要

In this study, the Plucker coordinates representation is used to formulate the ruled surface and the molecular path for pumping speed performance evaluation of a molecular vacuum pump. The ruled surface represented by the Plucker coordinates is used to develop a criterion for when gas molecules hit the pump surface wall. The criterion is applied to analyze the flow rate of a new developed vacuum pump in transition regimes by using the DSMC (Direct Simulation Monte Carlo) method. When a molecule flies in a neutral electrical field its path is a straight line. If the molecular path and the generators of a ruled surface are both represented by the Plucker coordinates, the position of the molecular hit on the wall can be verified by the reciprocal condition of the lines. The Plucker coordinates representation is quite convenient in the DSMC method for this three-dimensional molecular flow simulation.