Introduction of ions into a magnetic field

摘要

In a mass spectrometer that uses a space-restricted magnetic field, such as an ion cyclotron resonance mass spectrometer, ions with a wide mass range generated in an ion supply located outside the magnetic field are transported in the direction of the magnetic field lines to an ion storage device located inside the magnetic field without losing ions by guiding the ions through the region in which the magnetic field strength increases with a special ion guide. This ion guide consists of an arrangement of coaxial ring diaphragms which are alternately supplied with the phases of an RF voltage. In an alternative embodiment, the ion guide uses two wires wound in a double helix where each wire is supplied with one phase of a two-phase RF voltage.

主权项

1. An apparatus for introducing ions into a space-restricted magnetic field in a direction of magnetic field lines of the magnetic field, the ions being generated in an ion supply located outside the magnetic field and being transported to an ion storage device located inside the magnetic field; the apparatus comprising:
an ion guide having a plurality of coaxial ring diaphragms, each diaphragm having an axis parallel to the direction of magnetic field lines and being located in a region of greatest increase in the magnetic field between the ion supply and the ion storage device; an RF generator for generating RF voltages with at least two phases, the RF voltages being applied to plurality of ring diaphragms so that in the direction of magnetic field lines the ring diaphragms are connected to RF voltages with alternating phases; a first non-trapping multipole ion guide positioned adjacent to the ring diaphragm ion guide to guide the ions from the ion supply into the ring diaphragm ion guide; and a second non-trapping multipole ion guide positioned adjacent to the ring diaphragm ion guide to guide the ions from the ring diaphragm ion guide into the ion storage device.