Simulation and Calculation of Conductance and Pumping Speed for Cold Traps Based on Monte Carlo Method

With the rapid advancement of semiconductor manufacturing processes, there are increasing demands for the pumping performance of molecular pumps, particularly their water vapor pumping capacity. This has led to the widespread application of combined cryogenic cold traps used in conjunction with molecular pumps. Nitrogen conductance and water vapor pumping speed, which are closely related to the geometry of internal condensing plates, serve as critical parameters for evaluating cold trap performance. Experimental measurement of water vapor pumping speed proves extremely challenging due to the strong adsorption characteristics of water molecules. This paper systematically investigates the effects of condensing plate dimensions and folded edges on nitrogen conductance and water vapor pumping speed using Monte Carlo simulations. Furthermore, based on the simulation results, a cryogenic cold trap named EWP200N was developed and its nitrogen conductance was validated through a specially constructed conductance testing platform. Experimental results demonstrate that the nitrogen conductance of EWP200N reaches 2140 L/s, showing close agreement with the simulated value of 2023 L/s. This confirms the high accuracy of the proposed simulation methodology in quantitatively assessing both nitrogen conductance and water vapor pumping speed, offering significant engineering reference value for cryogenic cold trap design.