THE CALCULATION OF A MULTISTAGE TURBOMOLECULAR VACUUM PUMP

The dependencies of the main characteristics of a turbomolecular pump operating in the molecular regime of gas flow on the number of stages and their geometrical parameters are considered. Programs developed using the Monte Carlo method in a three-dimensional formulation, taking into account the influence of radial and axial clearances, make it possible to trace the full trajectory of each molecule through the entire flow path of the pump, as well as calculate the gas evolution flows. Determining the probabilities of molecules passing in the forward and reverse directions made it possible to establish the influence of the geometric parameters of the stages and their location in the flow path on the main characteristics of the pump.