APERTURE FOR GAS FLOW RESTRICTION

摘要

A mass spectrometer is disclosed comprising two vacuum chambers maintained at different pressures. The two vacuum chambers are interconnected by a differential pumping aperture (5a). The effective area of the opening (5a) between the two vacuum chambers may be varied by rotating a disk (7) having an aperture (7) a in front of the differential pumping aperture (5a) so as to vary the gas flow rate through the opening (5a) and between the two chambers.