Patent ID: 7365318
Filing Date: 2008-04-29
Classification: H01J

Abstract:
1. A system for compensating for an unbalanced or non-zero centerline radio-frequency potential in an quadrupolar ion trap, the unbalanced centerline created by a compensation feature that minimizes the non-linear field components created by one or more ejection slots in the ion trap, the system comprising: a quadrupolar ion trap comprising a plurality of electrodes arranged to define a trapping volume, the trapping volume having a centerline being substantially parallel to a Z axis; the plurality of electrodes including Y electrodes that are aligned with a Y axis, and X electrodes that are aligned with an X axis, said X axis being orthogonal to said Z axis, said X axis being rotated approximately ninety degrees from said Y axis; one or more ejections slots in at least one of the X electrodes through which ions are ejected from said ion trap,; a compensation feature, said compensation feature compensating for non-linear field components created by the one or more ejections slots, the compensation feature creating an unbalanced or non-zero centerline radio-frequency potential; a Y radio-frequency signal having a Y signal amplitude coupled said Y electrodes; and an X radio-frequency signal having an X signal amplitude that is selected to be greater than said Y signal amplitude, to thereby create a balanced or near zero centerline radio-frequency potential.