Ion guide electrode configurations for polarity-independent ion containment

An ion guide comprising:

• a first surface and a second surface facing one another with a gap therebetween;
• and
• a plurality of electrodes comprising a first arrangement of electrodes on the first surface and a second arrangement of electrodes on the second surface, the first arrangement of electrodes and the second arrangement of electrodes positioned opposite one another and defining an ion containment space in the gap, wherein:
• the first arrangement of electrodes comprises first electrodes and second electrodes alternately arranged on the first surface along a longitudinal axis of the ion containment space;
• the second arrangement of electrodes comprises third electrodes and fourth electrodes alternately arranged on the second surface along the longitudinal axis of the ion containment space;
• the first electrodes and the third electrodes are configured to receive RF voltages of a same phase;
• the second electrodes and the fourth electrodes are configured to receive RF voltages having a same phase and that are phase shifted with respect to the RF voltages received by the first electrodes and the third electrodes;
• main portions of the first electrodes and the third electrodes and main portions of the second electrodes and the fourth electrodes are configured to generate surface containment electric fields that inhibit movement of the ions within the ion containment space toward the first surface and the second surface;
• and
• opposing edge portions of the first electrodes and the fourth electrodes are configured to receive RF voltages that are phase-shifted with respect to one another and generate a first edge containment electric field that inhibit movement of the ions within the ion containment space toward a first side of the ion containment space.

An ion guide comprising:

• a plurality of electrodes arranged on opposing surfaces and defining an ion containment space in a gap between the opposing surfaces, wherein:
• each electrode of the plurality of electrodes comprises an elongate main portion and an edge portion at an end of the main portion, the edge portion being wider, along a longitudinal axis of the ion containment space, than the main portion;
• the plurality of electrodes are configured to receive RF voltages;
• and
• the plurality of electrodes are arranged so that opposing edge portions receive RF voltages that are phase-shifted with respect to one another.