Accurate measurement of pressure differences and the effect of baffle on pressure distribution in vacuum chamber during dynamic gas flow

The need to know the pressure in relatively large vacuum chambers arises at different measurements (calibration of vacuum gauges, outgassing measurements, etc.) and investigating the ways to minimize these pressure differences are of equal importance in such industrial as well as research applications. The experimental determination of the pressure differences between various gauge positions in a chamber of cylindrical shape and the effect of a baffle on pressure distribution are described in the paper. The pressure in the chamber was generated dynamically in the pressure range 0.1–133 Pa through adjustable gas flow into the chamber. Five identical capacitance diaphragm gauges (CDGs) were used in which one CDG remained fixed at the central position of the chamber while the other four (in two pairs) were mutually interchanged. The differences on the order of several percent between positions at different levels were calculated and the effect of the baffle was investigated which are specific for this chamber.