Patent ID: 6872940

Claim:
An ion transfer assembly for directing ions from an ionization source to a mass analyzer, comprising: a first partition element separating a viscous flow region from a transition flow region, the first partition element having a first aperture communicating from the viscous flow region to the transition flow region for transmitting a gas flow including ions entrained in a background gas; a second partition element separating the transition flow region from a molecular flow region, the second partition element having a second aperture; and a focusing element located in the transition region and configured to receive at least a portion of a gas flow transmitted through the first aperture, the focusing element defining a cavity extending along a center line between the first aperture and the second aperture, the cavity being shaped to create a gas dynamics effect that focuses a portion of the gas flow towards the second aperture along the center line; wherein no external voltage is applied to any of the first partition element, the second partition element or the focusing element.