Patent ID: 9196469
Filing Date: 2015-11-24
Classification: H01J

Abstract:
1. A method of selecting ions of interest from a beam of ions using an analyser, the method comprising: (i) providing an analyser comprising two opposing ion mirrors each mirror comprising inner and outer field-defining electrode systems elongated along an analyser axis z, each system comprising at least one electrode, the outer system surrounding the inner system; (ii) causing the beam of ions to fly through the analyser along a main flight path in the presence of an analyser field so as to undergo within the analyser at least one full oscillation in the direction of the analyser axis whilst orbiting about at least one electrode of the inner field defining electrode system or oscillating between at least two electrodes of the inner field defining electrode system; (iii) providing at least one set of electrodes adjacent to the main flight path; (iv) constraining the arcuate divergence from the main flight path of ions of interest by applying one set of voltages to at least one of the sets of electrodes adjacent to the main flight path when the ions of interest are in the vicinity of at least one of the at least one set of electrodes adjacent to the main flight path and applying at least one different set of voltages to the at least one set of electrodes adjacent to the main flight path when the ions of interest are not in the vicinity of at least one of the at least one set of electrodes adjacent to the main flight path; and, (v) ejecting the ions of interest from the analyser.