Patent ID: 7638765

Claim:
A field asymmetric ion mobility spectrometer (FAIMS) apparatus comprising: an ionization source for producing ions from a sample; an analyzer region comprising a first electrode and a second electrode disposed in a spaced-apart facing relationship one relative to the other so as to define an analytical gap therebetween, there being an ion inlet orifice defined through a first portion of the second electrode for supporting ion introduction into the analytical gap; a desolvation chamber disposed intermediate the ionization source and the analyzer region, such that ions that are produced by the ionization source travel downstream along an ion flow path through the desolvation chamber and into the analytical gap via the ion inlet orifice; a first gas conduit extending between an inlet end that is coupleable to a desolvation gas source and an outlet end that opens into the desolvation chamber, the first gas conduit for providing a flow of a desolvation gas into the desolvation chamber; and, a second gas conduit extending through a portion of the second electrode and between an inlet end that is couplable to a carrier gas source and an outlet end that is open adjacent to a portion of the ion flow path that is defined downstream relative to the desolvation chamber, the second gas conduit for providing a flow of a carrier gas separately from the flow of the desolvation gas, wherein the composition of the desolvation gas is different than the composition of the carrier gas, and wherein the outlet of the second gas conduit is in communication with a circumferential gas-flow distributing element that is recessed within a portion of a sidewall surface of the ion inlet orifice.