STABLE CONFINEMENT IN AN AZIMUTHALLY ASYMMETRIC FTICR ION-TRAP

Gravity, magnetic field gradients, and trap electric field errors all break the two-dimensional, azimuthal symmetry of an idealized ion trap . It has been suggested that these forces cause drifts which ultimatel y limit the trapping time of an ion cloud in a Fourier-transform ion-c yclotron-resonance mass spectrometry cell (F.H. Laukien, Int. J. Mass Spectrom. Ion Processes, 73 (1986) 81 (Ref. [1]).) In this paper we sh ow that magnetron motion prevents ion loss. The breaking of this adiab atic invariant by time-dependent phenomena such as vibration and elect rical noise is also analyzed. Under most conditions, the effect on the ion cloud is negligible.