Patent ID: 6163032
Filing Date: 2000-12-19
Classification: H01J

Abstract:
An ion transport system utilizing radio frequency (RF) voltage and direct current (DC) voltage to accelerate ions along a preselected path from a distal end toward a proximal end of the ion transport system, wherein electrode pairs are created to thereby at least partially cancel undesirable quadrapolar DC fields, said ion transport system comprising:at least four pairs of electrodes disposed generally equidistant from adjacent electrode pairs disposed about a common axis, wherein each pair of the at least four pairs of electrodes is comprised of tapered and generally parallel electrodes, and wherein each pair of the at least four pairs of electrodes are comprised of:a first electrode having a larger cross section at the distal end than at the proximal end; anda second electrode having a smaller cross section at the distal end than at the proximal end, wherein a nearest electrode of a nearest pair of electrodes is oppositely tapered relative to the second electrode, wherein the first and the second electrodes form an oppositely tapered electrode pair which at least partially cancels quadrapolar DC fields generated therefrom, and wherein the tapering of each electrode is at least one generally discrete step inward or outward from a central axis of each electrode pair, corresponding to an inward or outward direction of tapering, respectively.