Patent ID: 6995365

Claim:
A mass analysis system comprising: an ion injector providing a plurality of ions for analysis; an ion selection chamber receiving the plurality of ions from the ion injector, the ion selection chamber having an axis, the ion selection chamber further having an outer electrode disposed about the axis, and a plurality of inner electrodes disposed about the axis, the plurality of ions being accepted from the ion injector into the interstitial region between the outer electrode and the plurality of inner electrodes; and a power supply system connected to the electrodes of the ion selection chamber, where the power supply system selectively provides a constant voltage between the outer electrode and the plurality of inner electrodes to allow ions having different orbital periods to enter a stable orbit about the axis, and where the power supply system also selectively provides a changing voltage between the outer electrode and at least one of the plurality of inner electrodes to facilitate separation of ions of a selected mass-to-charge ratio from ions of non-selected mass-to-charge ratios based on the orbital periods of said plurality of ions about the axis.