Storage-Ring Ion Trap Derived from the Linear Quadrupole Radio-Frequency Mass Filter

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Abstract
The storage of protons and 3He ions in a circular storage‐ring ion trap with background gas collision‐limited loss time constants up to 8 min long under ultrahigh‐vacuum conditions is described. Storage‐ring traps were derived from the linear quadrupole rf mass filter by shaping the electrodes into circular and racetrack configurations. Operation of the traps with a trapping rf frequency Ω large compared to the secular ion oscillation frequency ω inhibited ion loss due to nonlinearities in the trapping fields. Long‐term ion storage in such traps may prove useful for radio‐frequency ion spectroscopic purposes.