Patent ID: 8378297
Filing Date: 2013-02-19
Classification: G01N

Abstract:
1. An apparatus for providing a continuous beam of selected ions filtered according to their electrical mobility, said apparatus comprising: an inlet; an outlet; a plurality of axial electrodes configured to produce an axial electric field in the direction of a central axis defined from the inlet towards the outlet; and, a plurality of deflector electrodes, symmetrically arranged around the central axis, powered with a combination of steady and periodically varying voltages configured to define a periodic deflector electric field, such that, trajectories of ions are caused to move away from the central axis during a half cycle of the periodic deflector electric field, and trajectories of the ions are moved towards the central axis during the remainder of the cycle of the periodic deflector electric field, wherein, after a cycle of the periodic deflector electric field, ion trajectories coalesce continuously to the central axis with only ion trajectories of the selected ions coalescing continuously to the outlet.