Patent ID: 7385193
Filing Date: 2008-06-10
Classification: H01J

Abstract:
1. A system for compensating for non-linear field components created by a field distortion feature in a quadrupolar ion trap, compensation provided by a geometric surface shaping which reduces the non-linear field components and creates a minimal centerline radio-frequency potential in an quadrupolar 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 comprising a pair of Y electrodes and a pair of X electrodes; the Y electrodes aligned with a Y axis, said Y electrodes being orthogonal to said Z axis and having inner Y electrode surfaces that have Y geometric shaping; the X electrodes aligned with an X axis, said X axis being orthogonal to said Z axis and being rotated approximately ninety degrees from said Y axis, said X electrodes having inner X electrode surfaces that have X geometric shaping; a Y electrode separation distance between said inner Y electrode surfaces along said Y axis, and an X electrode separation distance between said inner X electrode surfaces along said X axis, said X electrode separation distance being substantially the same as said Y electrode separation distance; one or more field distortion features in at least one of the electrodes, the field distortion features providing a less linear or more negative non-linear field characteristic in the ion trap; the geometric surface shapings of the electrodes comprising said distortion feature being selected to compensate for effects caused by said field distortion feature; and said system creating a balanced or near zero centerline radio-frequency potential at said centerline.