C-872 MASS GATE is a steering plate located at the entrance to the flight tube. Used to reject unwanted species from the mass spectrum. Usually pulsed to stability after unwanted low masses have passed by, or, pulsed to instability before unwanted high mass ions have passed by. The accuracy with which masses can be selected is limited by the mass separation which occurred between the ion source and mass gate, approxiamtely 250mm apart. It is mounted to insulating spacers and can be easily removed.
Screened openings allow improved conductance to the pumping sideport in the flight tube.
It is sealed with lightly lubricated Viton o-rings and passes through a ball valve into the high vacuum. The valve is mounted to the assembly by Swagelok fittings using TFE ferrules so that everything can be taken apart and reassembled easily. The customer can fabricate custom sample tips in special configurations. He can also design custom probe features such as heated tips as long as the diameter is the same. The inlet can be pumped by membrane or ballasted rotary vacuum pumps.