ION MOBILITY SPECTROMETER WITH VARIABLE EFFECTIVE DRIFT LENGTH

摘要

An ion mobility separator or spectrometer is disclosed comprising an inner cylinder (2) and an outer cylinder (1). The inner cylinder (2) and the outer cylinder (1) define an annular volume (3) through which ions are transmitted. One or more spiral electrodes a-f are arranged on a surface of the inner cylinder (2) and/or on a surface of the outer cylinder (1). A first device is arranged and adapted to maintain a DC electric field and/or a pseudo- potential force which acts to urge ions from a first end of the ion mobility separator or spectrometer to a second end of the ion mobility separator or spectrometer. A second device is arranged and adapted to apply one or more transient DC voltages to the one or more spiral electrodes in order to urge ions towards the first end of the ion mobility separator or spectrometer. The net effect is to extend the effective path length of the ion mobility separator.