Pole electrodes (150) are disclosed for use in an ion reaction apparatus, e.g., an electron induced dissociation cell, to reduce fouling due to polymer build-up and increase the useful lifetime of such electrodes. To reduce fouling, the novel pole electrode designs include a X-shaped aperture (160) in lieu of the conventional central circular aperture. The pole electrodes are particularly useful in systems having a plurality of branched electrodes (152) defining a first axis for controlled passage of charged ions and a transverse axis for passage of an electron beam. The pole electrodes are adapted for disposition between an electron source and the branched electrodes to provide an aperture for passage of an electron beam while also impeding escape of ions and reaction products from the apparatus. The X-shaped aperture eliminates or reduces the portion of the pole electrode surface that is most prone to fouling by polymeric build-up.

An ion confinement device (2) comprising: a plurality of electrodes arranged and configured for confining ions when an AC or RF voltage is applied thereto; and at least one inductive ballast (10a,10b), each ballast connected to at least some of said electrodes so as to form a resonator circuit therewith.

An ion guide includes electrodes elongated along an axis from an entrance end to an exit end and spaced around the axis to surround an interior. The electrodes have polygonal shapes with inside surfaces disposed at a radius from the axis and having an electrode width tangential to a circle inscribed by the electrodes. An aspect ratio of the electrode width to the radius varies along the axis. The electrodes are configured to generate a two-dimensional RF electrical field in the interior having a multipole composition comprising one or more lower-order multipole components and one or more higher-order multipole components and varying along the axis in accordance with the varying aspect ratio, and having an RF voltage amplitude that varies along the axis.

An ion guide includes electrodes elongated along an axis from an entrance end to an exit end and spaced around the axis to surround an interior. The electrodes have polygonal shapes with inside surfaces disposed at a radius from the axis and having an electrode width tangential to a circle inscribed by the electrodes. An aspect ratio of the electrode width to the radius varies along the axis. The electrodes are configured to generate a two-dimensional RF electrical field in the interior having a multipole composition comprising one or more lower-order multipole components and one or more higher-order multipole components and varying along the axis in accordance with the varying aspect ratio, and having an RF voltage amplitude that varies along the axis.

An ion analyzer includes an ion optical element having four rod electrodes around an optical axis, for transferring ions from their surrounding space to the subsequent stage while converging the ions. To create an RF electric field within this space, a voltage supplier applies RF voltages of opposite polarities to two pairs of electrodes facing each other across the axis. The cross-sectional shape of each electrode in a plane orthogonal to the axis has a first side having width w facing the axis and is tangent to a circle of radius r.sub.0 around the axis, and two adjacent sides connected to the ends of the first side at an angle determined so that an RF field created by the adjacent sides exerts no influence within the space. The ratio w/r.sub.0 is determined so that the amount of dodecapole field component becomes a predetermined value or does not exceed it.

A mass spectrometer collision cell system, comprising: a gas containment vessel comprising an internal chamber having ion inlet and ion outlet ends and a cross-sectional area, A.sub.chamber; a gas inlet aperture; first and second gas outlet apertures that are disposed at or proximal to the ion inlet and outlet ends, respectively, and that have respective outlet aperture cross-sectional areas, A.sub.aperture1 and A.sub.aperture2, and an average outlet aperture cross-sectional area, A.sub.aperture.sup.ave; a longitudinal axis of the chamber extending from the ion inlet end to the ion outlet end and having a length, L.sub.chamber; and a set of multipole rod electrodes, at least a portion of each multipole rod electrode being within the chamber, wherein the values of A.sub.chamber, L.sub.chamber and A.sub.aperture.sup.ave are such that the combined gas conductance of the chamber and the gas outlet apertures is not greater than 95 percent of the gas conductance of the gas outlet apertures alone.

The present invention relates to the technical field of mass spectra. Disclosed are a novel ion storage system and method based on a quadrupole-ion trap tandem mass spectrometry. The system sequentially comprises a heating capillary, a tube lens, a skimmer, a first ion guide, a second ion guide, a quadrupole mass analyzer, an ion trap mass analyzer, and a detector; a first lens is provided between the first ion guide and the second ion guide; a second lens and a third lens are provided between the second ion guide and the quadrupole mass analyzer, wherein operation modes of the first ion guide and the second ion guide comprise an ion transmission mode and an ion storage mode. Compared with conventional time sequence control methods, more ions are stored during the same time according to the present invention, thereby improving the sensitivity of the instrument.

The invention provides (a) a time-of-flight mass spectrometer with an acceleration region, a single-stage or multi-stage reflector, and an ion detector, further comprising an additional reflector whose potential has, at least in a subregion, a two-dimensional logarithmic potential component and a two-dimensional octopole potential component, and (b) methods for operating the time-of-flight mass spectrometer.

A mass spectrometry method comprises: receiving a stream of ions at an inlet end of an ion transport device; accumulating a first portion of the ion stream at a first electrical potential well at a first position within the ion transport device between the inlet and outlet ends; creating a generally descending potential profile within the ion transport apparatus between a second position and the outlet end and, simultaneously, creating a second potential well at a third position within the ion transport apparatus, the second position disposed between the first position and the inlet end, the third position disposed between the second position and the inlet end; and transporting the accumulated first portion of the ion stream from the first position to the outlet end under the impetus of the generally descending potential profile and, simultaneously, accumulating a second portion of the ion stream at the second potential well.

A mass spectrometer comprises an orifice plate having an orifice, a first multipole ion guide in a first chamber downstream of said orifice plate, said first multipole ion guide comprising a plurality of rods, and a second multipole ion guide in a second chamber downstream of said first chamber, said second multipole ion guide comprising a plurality of rods. A first ion lens is between the first and the second multipole ion guides. A third multipole ion guide is in a third chamber downstream of the second chamber, the third multipole ion guide comprises a plurality of rods. A second ion lens is between the second and third chambers. A tunable DC voltage source applies a tunable DC offset voltage to at least one of the above ion guide and ion lenses to increase an axial kinetic energy of the ions to cause at least one of declustering and/or fragmentation.