Influence of the blocking plate located in the pumping chamber on the gas flux distributions in high vacuum primary standards

The paper presents the results of the Monte-Carlo computations of the gas flux density distribution in the chambers of typical calibration systems, as a function of two parameters: the diameter of the blocking plate, placed in the pumping chamber, and the backstream from the pump. It was found that the backstream from the pumping chamber to the calibration chamber mainly depends on the diameter of the blocking plate, and it increases significantly with the blocking plate diameter.