Patent ID: 6888128

Claim:
A gas sampling system for an ion mobility spectrometer comprising: a first gas pump that provides a first gas flow at a partial gas vacuum compared to ambient gas pressure; a second gas pump that provides a second gas flow, different from said first gas flow, at a partial gas pressure compared to the ambient gas pressure; a first orifice in communication with the first gas pump to provide the first gas flow in a first gas flow direction toward the first gas pump, wherein the first gas flow is external to said ion mobility spectrometer; tubulation means connecting said first orifice to said ion mobility spectrometer; a plurality of orifices in communication with said second gas pump to provide said second gas flow that substantially surrounds said first gas flow to increase vacuum at a sampling location distal from the first orifice and; means for directing said second gas flow in a direction with a normal axis of said second gas flow and a direction of flow both being substantially perpendicular to said first gas flow direction and enclosing in part a gas sampling volume.