Patent ID: 8258470
Filing Date: 2012-09-04
Classification: H01J

Abstract:
1. A mass analyzer comprised of: a. an ion source; b. an inlet assembly having an input and an output; c. a quadrupole mass analyzer assembly, said quadrupole mass analyzer assembly adjacent said inlet assembly; d. an exit lens having an input and an output, said exit lens adjacent exit of said quadrupole mass analyzer assembly; and e. means for supplying electric potentials to said inlet assembly, said means supplying an electrostatic or direct current potential and an electrodynamic or radio frequency potential operating at least one frequency that is 180 degrees phase shifted with respect to a radio frequency potential applied to said quadrupole mass analyzer assembly; whereby defocusing fringe fields at the entrance to said quadrupole mass analyzer assembly are cancelled out by the formation of a field free or near-field free region at the intersection of, or midpoint between, said output of said inlet assembly and input of said quadrupole mass analyzer assembly, allowing substantially all gas-phase ions from said ion source to be urged by said electric potentials means into and through said inlet assembly, passing uninhibited through said intersection and directed into said quadrupole for mass analysis and detection.