Influence of Chamber Structure on Pumping Performance of Sputter-Ion Pump:A Monte Carlo Simulation

The gas molecule flow in the vacuum chamber, housing a sputter-ion pump cathode, was mathematically formulated with free molecule flow model, theoretically analyzed and numerically simulated in Monte Carlo method with self-developed program.The influence of the chamber structures, including the “I, T and U” shapes, on the reverse flow-rate, (or regurgitation) was investigated by calculating the inlet to outlet ratio of molecules.The simulated results show that the chamber structure has a major impact.To be specific, when it comes to the pumping performance under the same experimental conditions, the “I-, T-and U-shaped” vacuum chambers can be listed in a descending order.In addition, the pumping performance was found to considerably depend on the distance between the outlet and the sputter-ion cathode of the sputter-ion pump.