A converging RF multipole ion guide for ion beam shaping

摘要

A multipole ion guide 600 for use in a mass spectroscopy system comprises: an input with a geometry configured to create a RF multipolar field of order hexapolar or greater; and an output comprising a geometry configured to create two or more substantially quadrupolar RF field regions (see Figs 7 & 10). The multipole ion guide 600 comprises rods 601 having a first end 604 and a second end 605 disposed about an axis 609. Each of the rods 601 is disposed at a respective greater distance from the axis 609 at the first end 604 than at the second end 605. Also disclosed is means for applying a direct current (DC) voltage drop along a length of each of the rods 601.