Patent ID: 7019290
Filing Date: 2006-03-28
Classification: H01J

Abstract:
1. A method of operating a multipole ion guide in a mass spectrometer, the method comprising: (a) providing a rod set including at least a first pole and a second pole, wherein the rod set has first and second ends; (b) providing a first end device adjacent to the first end of the rod array; (c) applying a first pole RF voltage to the first pole; (d) applying a second pole RF voltage to the second pole, wherein the second pole RF voltage is 180° out of phase with the first pole RF voltage and wherein the first pole RF voltage has an amplitude about equal to an amplitude of the second pole RF voltage; (e) applying a first end device DC voltage to the first end device, thereby producing a first fringing field in the ion guide adjacent the first end of the rod array; (f) applying a first end device RF voltage to the first end device, wherein the first end device RF voltage is in phase with the first pole RF voltage.