A Time of Flight mass analyzer is disclosed comprising an annular ion guide having a longitudinal axis and comprising a first annular ion guide section and a second annular ion guide section. Ions are introduced into the first annular ion guide section so that the ions form substantially stable circular orbits within the first annular ion guide section about the longitudinal axis. An ion detector is disposed within the annular ion guide. Ions are orthogonally accelerated in a first axial direction from the first annular ion guide section into the second annular ion guide section. An axial DC potential is maintained along at least a portion of the second annular ion guide section so that the ions are reflected in a second axial direction which is substantially opposed to the first axial direction. The ions undergo multiple axial passes through the second annular ion guide section before being detected by the ion detector.

An electrostatic ion trap for mass analysis includes a first array of electrodes and a second array of electrodes, spaced from the first array of electrode. The first and second arrays of electrodes may be planar arrays formed by parallel strip electrodes or by concentric, circular or part-circular electrically conductive rings. The electrodes of the arrays are supplied with substantially the same pattern of voltage whereby the distribution of electrical potential in the space between the arrays is such as to reflect ions isochronously in a flight direction causing them to undergo periodic, oscillatory motion in the space, focused substantially mid-way between the arrays. Amplifier circuitry is used to detect image current having frequency components related to the mass-to-charge ratio of ions undergoing the periodic, oscillatory motion.

For improving sensitivity, dynamic range, and specificity of GC-MS analysis there are disclosed embodiments of novel apparatuses based on improved characteristics of semi-open source with electron impact ionization, providing much higher brightness compared to known open EI sources. In an implementation, the source becomes compatible with multi-reflecting TOF analyzers for higher resolution analysis for improving detection limit. With improved schemes of spatial and temporal refocusing there are proposed various tandem TOF-TOF spectrometers with PSD, CID, and SID fragmentation and using either singly reflecting TOF or MR-TOF analyzers.

A multi-reflection mass spectrometer is provided comprising two ion-optical mirrors, each mirror elongated generally along a drift direction (Y), each mirror opposing the other in an X direction, the X direction being orthogonal to Y, characterized in that the mirrors are not a constant distance from each other in the X direction along at least a portion of their lengths in the drift direction. In use, ions are reflected from one opposing mirror to the other a plurality of times while drifting along the drift direction so as to follow a generally zigzag path within the mass spectrometer. The motion of ions along the drift direction is opposed by an electric field resulting from the non-constant distance of the mirrors from each other along at least a portion of their lengths in the drift direction that causes the ions to reverse their direction.

An open electrostatic trap mass spectrometer is disclosed for operation with wide and diverging ion packets. Signal on detector is composed of signals corresponding to multiplicity of ion cycles, called multiplets. Using reproducible distribution of relative intensity within multiplets, the signal can be unscrambled for relatively sparse spectra, such as spectra past fragmentation cell of tandem mass spectrometer, past ion mobility and differential ion mobility separators. Various embodiments are provided for particular pulsed ion sources and pulsed converters such as orthogonal accelerators, ion guides, and ion traps. The method and apparatus enhance the duty cycle of pulsed converters, improve space charge tolerance of the open trap analyzer and extends the dynamic range of time-of-flight detectors.

A multi-reflection mass spectrometer comprising two ion-optical mirrors, each mirror elongated generally along a drift direction (Y), each mirror opposing the other in an X direction and having a space therebetween, the X direction being orthogonal to Y; the mass spectrometer further comprising one or more compensation electrodes each electrode being located in or adjacent the space extending between the opposing mirrors; the compensation electrodes being configured and electrically biased in use so as to produce, in at least a portion of the space extending between the mirrors, an electrical potential offset which: (i) varies as a function of the distance along the drift length, and/or; (ii) has a different extent in the X direction as a function of the distance along the drift length. In a preferred embodiment the period of ion oscillation between the mirrors is not substantially constant along the whole of the drift length.

A multi-reflection time of flight mass spectrometer comprises a mass analyser with opposing mirror electrodes and a focal plane correction electrode. Each mirror electrode is elongated generally along a drift direction. The focal plane correction electrode extends along at least a portion of the drift direction in or adjacent the space between the mirror electrodes. Ions are injected into the mirror electrodes and an electrical potential provided to the mirror electrodes reflects the ions in the resulting ion beam and causes the ions to follow a zig zag path as they drift along the mirror electrodes. An electrical potential is also provided to the focal plane correction electrode to set the focal plane position of the ion beam to coincide with a detector surface of an ion detector placed at the end of the ions' path.

An electrostatic trap such as an orbitrap is disclosed, with an electrode structure. An electrostatic trapping field of the form U(r, , z) is generated to trap ions within the trap so that they undergo isochronous oscillations. The trapping field U(r, , z) is the result of a perturbation W to an ideal field U(r, , z) which, for example, is hyperlogarithmic in the case of an orbitrap. The perturbation W may be introduced in various ways, such as by distorting the geometry of the trap so that it no longer follows an equipotential of the ideal field U(r, , z), or by adding a distortion field (either electric or magnetic). The magnitude of the perturbation is such that at least some of the trapped ions have an absolute phase spread of more than zero but less than 2 radians over an ion detection period T.sub.m.

A method of reflecting ions in a multireflection time of flight mass spectrometer is disclosed. The method includes guiding ions toward an ion mirror having multiple electrodes, and applying a voltage to the ion mirror electrodes to create an electric field that causes the mean trajectory of the ions to intersect a plane of symmetry of the ion mirror and to exit the ion mirror, wherein the ion are spatially focussed by the mirror to a first location and temporally focused to a second location different from the first location. Apparatus for carrying out the method is also disclosed.

A mass analyser comprises a pair of electrode arrays. Each array has a set of focusing electrodes which are supplied, in use, with voltage to create an electrostatic field in a space between the electrode arrays causing ions to undergo periodic, oscillatory motion in the space, ions passing between electrodes of the sets of focusing electrodes and being repeatedly focused at a centre plane, mid-way between the electrode arrays. At least one electrode of each set of focusing electrodes has an electrode surface closer to the centre plane than the electrode surfaces of other electrodes of the same set. The analyser may be an ion trap mass analyser or a multi-turn ToF mass analyser.