Ion Guide with Configurable Length Electric Field Regions

A system comprising:

• a memory storing instructions;
• and
• one or more processors communicatively coupled to the memory and configured to execute the instructions to perform a process comprising:
• directing a power source to apply a set of radio-frequency (RF) voltage waveforms to a series of electrodes disposed between a first end of an ion guide and a second end of the ion guide, the ion guide configured to receive ions, the series of electrodes defining an ion occupation volume and an axis of the ion guide between the first end and the second end, the RF voltage waveforms configured to confine the ions within the ion occupation volume and generate a plurality of moving pseudopotential wells that exert forces that urge the ions to migrate along the axis towards the second end,
• directing the power source to apply, simultaneously with the application of the set of RF voltage waveforms, a first set of direct-current (DC) voltages to a first set of electrodes included in the series of electrodes and that are adjacent to the first end, the first set of DC voltages configured to create a first electric field in a first region of the ion guide corresponding to a location of the first set of electrodes, and
• directing the power source to apply, simultaneously with the application of the set of RF voltage waveforms and the first set of DC voltages, a second set of DC voltages to a second set of electrodes included in the series of electrodes and that are adjacent to the second end, the second set of DC voltages configured to create a second electric field in a second region of the ion guide corresponding to a location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude that is greater than a maximum amplitude of the first electric field;
• wherein the first electric field and the second electric field generate forces that urge the ions to migrate along the axis towards the first end.

A method comprising:

• directing a power source to apply a set of radio-frequency (RF) voltage waveforms to a series of electrodes disposed between a first end of an ion guide and a second end of the ion guide, the ion guide configured to receive ions, the series of electrodes defining an ion occupation volume and an axis of the ion guide between the first end and the second end, the RF voltage waveforms configured to confine the ions within the ion occupation volume and generate a plurality of moving pseudopotential wells that exert forces that urge the ions to migrate along the axis towards the second end;
• directing the power source to apply, simultaneously with the application of the set of RF voltage waveforms, a first set of direct-current (DC) voltages to a first set of electrodes included in the series of electrodes and that are adjacent to the first end, the first set of DC voltages configured to create a first electric field in a first region of the ion guide corresponding to a location of the first set of electrodes;
• and
• directing the power source to apply, simultaneously with the application of the set of RF voltage waveforms and the first set of DC voltages, a second set of DC voltages to a second set of electrodes included in the series of electrodes and that are adjacent to the second end, the second set of DC voltages configured to create a second electric field in a second region of the ion guide corresponding to a location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude that is greater than a maximum amplitude of the first electric field;
• wherein the first electric field and the second electric field generate forces that urge the ions to migrate along the axis towards the first end.