Patent ID: 9099290
Filing Date: 2015-08-04
Classification: H01J

Abstract:
1. A method of operating a multipole in a collision cell, the multipole comprising a first portion, a second portion and an intermediate portion therebetween, the method comprising the step of operating the first and second portions at respective first and second q values lower than a third q value at the intermediate portion; wherein the step of operating the first and second portions at respective first and second q values lower than the third q value at the intermediate portion comprises at least one of: positioning the intermediate portion radially closer to a central axis of the multipole than the first portion and the second portion; or applying a different RF voltage amplitude to the intermediate portion relative to the RF voltage amplitude applied to the first portion and the second portion; or applying a different RF voltage frequency to the intermediate portion relative to the RF voltage frequency applied to the first portion and the second portion.