Ion guide within pulsed converters
AssigneeMicromass UK Limited
InventorAnatoly Verenchikov
Life of this patent
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Abstract
Elongation of orthogonal accelerators is assisted by ion spatial transverse confinement within novel confinement means, formed by spatial alternation of electrostatic quadrupolar field (22). Contrary to prior art RF confinement means, the static means provide mass independent confinement and may be readily switched. Spatial confinement defines ion beam (29) position, prevents surfaces charging, assists forming wedge and bend fields, and allows axial fields in the region of pulsed ion extraction, this way improving the ion beam admission at higher energies and the spatial focusing of ion packets in multi-reflecting, multi-turn and singly reflecting TOF MS or electrostatic traps.
Claims19
A pulsed ion accelerator for a mass spectrometer comprising:
- an ion guide portion having electrodes arranged to receive ions travelling along a first dimension, including a plurality of DC electrodes spaced along the first dimension;
- DC voltage supplies configured to apply different DC potentials to different ones of said DC electrodes such that when ions travel through the ion guide portion along the first dimension they experience an ion confining force, generated by the DC potentials, in at least one dimension orthogonal to the first dimension;
- and
- a pulsed voltage supply configured to apply a pulsed voltage to at least one electrode for pulsing ions in a second dimension substantially orthogonal to the first dimension.
A method of mass spectrometric analysis within an isochronous electrostatic field, comprising the following step:
- (a) forming electrostatic quadrupolar field in the XY-plane, which is spatially alternated along the orthogonal Z-direction;
- (b) passing an ion beam along the Z-direction;
- (c) pulsed accelerating of the moving ions in the X-direction, thus forming ion packets.
A mass spectrometer, comprising:
- (a) An ion source, generating an ion beam along a first drift Z-direction at some initial energy;
- (b) An orthogonal accelerator, admitting said ion beam into a storage gap, pulsed accelerating a portion of said ion beam in the second orthogonal X-direction, thus forming ion packets with a smaller velocity component in the Z-direction and with the major velocity component in the X-direction;
- (c) An electrostatic multi-pass (multi-reflecting or multi-turn) mass analyzer, built of ion mirrors or electrostatic sectors, substantially elongated in said Z-direction to form an electrostatic field in an XY-plane orthogonal to said Z-direction;
- said two-dimensional field provides for a field-free ion drift in the Z-direction towards a detector, and for an isochronous repetitive multi-pass ion motion within an isochronous mean ion trajectory surface—either symmetry s-XY plane of said ion mirrors or curved s-surface of electrostatic sectors;
- (d) within said storage gap of said orthogonal accelerator, an ion guide composed of electrodes, symmetrically surrounding said ion beam;
- said electrodes are energized by at least two distinct DC potentials to form an electrostatic quadrupolar field in the XY-plane, which is spatially alternated along the Z-direction.
Dependencies are inferred from the claim text.