Introduction of ions into kingdon ion traps
AssigneeBruker Daltonik GmbH
InventorsClaus Koster, Jochen Franzen
Life of this patent
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Abstract
In a Kingdon ion trap in which harmonic ion oscillation in a potential well in a longitudinal direction is completely decoupled from ion oscillation in a direction transverse to the longitudinal direction, ions enter the trap via an entrance tube extending through, but electrically insulated from, one of the Kingdon trap housing electrodes and located outside the minimum of the potential well in the longitudinal direction. The geometry of the Kingdon trap is arranged so that the oscillating ions introduced through the entrance tube cannot return to the entrance tube until they have performed several longitudinal oscillations during which time heavy ions can be introduced into the trap.
Claims14
A Kingdon ion trap comprising:
- housing electrodes extending in a longitudinal direction;
- inner electrodes spaced from the housing electrodes in a direction transverse to the longitudinal direction, the housing electrodes and the inner electrodes being shaped so that ions introduced into the trap can oscillate harmonically in a potential well in the longitudinal direction and independently oscillate in the transverse direction when a DC electric field is established between the housing electrodes and the inner electrodes;
- and
- an entrance tube that extends through one of the housing electrodes and is insulated therefrom and allows ions to enter the ion trap.
A method for storing ions, comprising:
- (a) providing a Kingdon ion trap having housing electrodes extending in a longitudinal direction, inner electrodes spaced from the housing electrodes in a direction transverse to the longitudinal direction, the housing electrodes and the inner electrodes being shaped so that ions introduced into the trap can oscillate harmonically in a potential well in the longitudinal direction and independently oscillate in the transverse direction when a DC operating voltage is applied between the housing electrodes and the inner electrodes and an entrance tube that extends through one of the housing electrodes and is insulated therefrom and allows ions to enter the ion trap;
- (b) applying to the entrance tube an injection potential which differs from the DC operating voltage by five to twenty percent of the operating voltage;
- (c) generating an ion cloud;
- (d) transferring ions from the ion cloud through the entrance tube into the Kingdon trap;
- and
- (e) after heaviest ions of interest have entered the Kingdon trap, applying to the entrance tube a measuring phase potential which differs from the DC operating voltage by a maximum of five percent of the operating voltage.
A mass spectrometer comprising:
- an ion source for producing ions;
- a Paul ion trap for receiving the ions;
- and
- a Kingdon ion trap for receiving ions from the Paul ion trap, the Kingdon ion trap having,
- housing electrodes extending in a longitudinal direction;
- inner electrodes spaced from the housing electrodes in a direction transverse to the longitudinal direction, the housing electrodes and the inner electrodes being shaped so that ions introduced into the Kingdon ion trap can oscillate harmonically in a potential well in the longitudinal direction and independently oscillate in the transverse direction when a DC electric field is established between the housing electrodes and the inner electrodes;
- and
- an entrance tube that extends through one of the housing electrodes and is insulated therefrom and allows ions to enter the Kingdon ion trap.
Dependencies are inferred from the claim text.