Patent ID: 8148680

Claim:
A method of transporting gas and entrained ions between a first, relatively high pressure region and a second, relatively low pressure region, comprising the steps of: providing, between the high and low pressure regions, an ion transfer conduit including an electrode assembly which defines an ion transfer channel through which the gas and entrained ions pass, and which has a first set of electrodes of a first width D 1 in the longitudinal direction of the ion transfer conduit, and a second set of electrodes of a second width D 2 (≧D 1 ) in the longitudinal direction and interleaved with the first set of electrodes; supplying a DC voltage of magnitude V 1 and a first polarity to the first set of electrodes and a DC voltage of magnitude V 2 (|V 2 |≦|V 1 |) and a second, opposite polarity relative to the average voltage distribution in the longitudinal direction of the electrode assembly, to the second set of electrodes; and controlling the pressure of the ion transfer conduit so as to maintain viscous flow of gas and ions within the ion transfer channel.