Patent ID: 8487247

Claim:
An atmospheric pressure ion source comprising: a capillary having a first opening, a second opening, and passage extending from the first opening to the second opening, the first opening being in a first pressure region at about atmospheric pressure and the second opening being in the second pressure region at a partial vacuum of about 3 Torr or less, the capillary being positioned so that during operation of the system ions enter the passage via the first opening and exit the passage via the second opening; a vacuum chamber defining the second pressure region and having an inlet configured to receive ions from the second opening of the capillary, the vacuum chamber including an extracting aperture positioned so that during operation of the system ions enter a third pressure region at about 10 −2 Torr or less via the extracting aperture at a location subsequent to a quiet zone in the gas flow exhibiting a Mach disk in the gas flow.