Laterally-extended trapped ion mobility spectrometer

A trapped ion mobility separator comprising:

• an ion region through which ions travel along an axis from an entrance to an exit, the ion region containing a gas through which the ions pass and having an elongate cross-sectional profile perpendicular to the axis with a long dimension and a short dimension;
• a series of electrode structures that are arranged along the axis, and that encompass the elongate cross-sectional profile along at least said long dimension, each electrode structure comprising an elongate electrode that extends parallel to said long dimension, the elongate electrodes being located, respectively, on first and second sides of the ion region relative to the short dimension in an alternating arrangement along the axis, wherein the elongate electrodes of the first side are arranged in a first series of adjacent elongate electrodes and the elongate electrodes of the second side are arranged in a second series of adjacent elongate electrodes, wherein each of the adjacent elongate electrodes of the first side have a relative spacing equal to a relative spacing of each of the elongate electrodes of the second side, and wherein, relative to the adjacent elongate electrodes of the first side, positioning of the adjacent elongate electrodes of the second side along the axis is offset by a distance equal to half of said relative spacing;
• at least one RF generator that generates varying voltage potentials that are applied to the electrode structures including a first RF voltage a first phase of which is applied to every other elongate electrode on the first side of the ion region while a phase of the first RF voltage opposite to the first RF voltage first phase is applied to the remaining elongate electrodes on the first side, the at least one RF generator further generating a second RF voltage that has a frequency different than that of the first RF voltage, a first phase of the second RF voltage being applied to every other elongate electrode of the second side of the ion region while a phase of the second RF voltage opposite to the second RF voltage first phase is applied to the remaining elongate electrodes on the second side, the first and second RF voltages providing an electric confining field that exerts a confinement force on the ions in the ion region relative to said short dimension;
• a first force-generator that exerts a first axial force on the ions along the axis;
• and
• a second force-generator that exerts a second axial force on the ions along the axis which is counteracting the first axial force;
• wherein at least one of the first and second axial forces has an effect on the ions that is ion mobility dependent, and wherein at least one of the first and second axial forces varies spatially along the axis such that ions are trapped and separated by ion mobility along the axis during an accumulation phase, and wherein the first and/or the second force generator is configured to vary the magnitude of the first force relative to the second force over time during an elution phase such that the ions are progressively driven to the exit as a function of ion mobility.