Apparatus for trapping ions

Abstract

Apparatus for trapping ions comprises an array of electrodes 101 extending along a surface 103, said electrodes supplied with oscillatory RF voltages such that each electrode in the array has a different phase to each adjacent electrode, (thereby forming an RF ion carpet). Ions are trapped within the apparatus by application of a DC trapping voltage to one or more further electrodes 102, said voltage preferably being a time-varying DC voltage that increases in magnitude with time. To extract ions from the trap, the oscillatory voltages supplied to the array are first quenched during a delay period, and a focusing voltage is applied to the further electrode(s) to force the ions towards the array. After the delay period, an extraction voltage is applied to at least one of the array of electrodes and / or further electrodes. The trapping region defined by the RF electrode array and the one or more further electrodes may have relatively high- and relatively low-pressure regions, 106A & 106B, separated by a gas restrictor 107.

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