Abstract: A miniature mass spectrometer that may be coupled to an atmospheric pressure ionisation source is described. Ions pass through a small orifice from a region at atmospheric pressure or low vacuum, and undergo efficient collisional cooling as they transit a very short, differentially pumped ion guide. A narrow beam of low energy ions is passed through a small aperture and into a separate chamber containing the mass analyser.

Abstract: An orbital ion trap for electrostatic field ion trapping which includes an electrode structure defining an internal volume of the trap with at least some of electrode surfaces shaped to substantially follow equipotential lines of an ideal quadro-logarithmic electric potential around a longitudinal axis z. The ideal electric potential has an inner potential canyon, an outer potential canyon, and a low potential passage therebetween. The trap includes a trapping voltage supply which provides trapping voltages on the electrodes to generate a trapping electrostatic potential within the internal volume of the trap. The trapping electrostatic potential closely approximates at least a part of the ideal electric potential in at least a part of the internal volume of the trap.

Abstract: A mass spectrometer is disclosed comprising a quadrupole rod set ion trap wherein a potential field is created at the exit of the ion trap which decreases with increasing radius in one radial direction. Ions within the ion trap are mass selectively excited in a radial direction. Ions which have been excited in the radial direction experience a potential field which no longer confines the ions axially within the ion trap but which instead acts to extract the ions and hence causes the ions to be ejected axially from the ion trap.

Abstract: The present invention relates to a parallel IMS and MS measurement method where a sample flow is split and delivered to an IMS and a MS in parallel. A parallel acquisition MS/IMS method is used to supplement LC-MS and or MS data by using a synchronized MS/IMS acquisition.

Abstract: An ion mobility spectrometer has an inlet for an analyte substance opening into an ionization region that produces ions of the substance. Parallel grid electrodes extend laterally across the ion flow path and apply an electric field to the ions that is switchable between a relatively low magnitude alternating field that varies in magnitude over multiple periods and an asymmetric alternating field of sufficiently high magnitude to cause differential mobility effects. A collector collects the passed ions, and an indication of the nature of the analyte substance is produced from the collected ions passed during both the low and high field intervals. Also disclosed is the application of a substantially alternating field between the electrodes, which field varies between a low value and a higher value over a time exceeding that of the alternating period.

Abstract: A mass spectrometer having an ion guide with an axial field is described. The ion guide includes electrodes with longitudinally extending gaps and inserts configured to be proximate to the gaps.

Abstract: A system and method for mass spectrometry including a curtain gas chamber defined by a curtain plate having an aperture for receiving ions from an ion source and an orifice plate having an inlet into a mass spectrometer. At least one barrier separates the curtain chamber into a first curtain gas chamber region and a second curtain gas chamber region. At least one gas source provides a gas inflow into the second curtain gas chamber region and a gas outflow into the first curtain gas chamber region, a portion of the gas outflow directed out of the aperture. A heating element heats the gas inflow, a portion of the heated gas inflow directed into the inlet of the mass spectrometer wherein the portion of the heated gas inflow can be at a substantially higher temperature than the portion of the gas outflow.

Abstract: A method of dissociating ions in a multipole ion guide is disclosed. A stream of charged ions is supplied to the ion guide. A main RF field is applied to the ion guide to confine the ions through the ion guide. An excitation RF field is applied to one pair of rods of the ion guide. The ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions. The multipole ion guide is, but not limited to, a quadrupole, a hexapole, and an octopole.

Abstract: A two-dimensional substantially quadrupole field is provided. The field comprises a quadrupole harmonic of amplitude A2 and an octopole harmonic of amplitude A4, wherein A4 is greater than 0.01% of A2, A4 is less than 5% of A2, and, for any other higher order harmonic with amplitude An present in the field, n being any integer greater than 2 except 4, A4 is greater than ten times An.

Abstract: An ion mobility spectrometer has a reaction region separated from a drift region by an electrostatic gate. A doping circuit supplies a dopant to the reaction region but the drift region is undoped. Two high field ion modifiers are located one after the other in the drift region. One ion modifier can be turned on to remove dopant adducts from the admitted ions, or both ion modifiers can be turned on so that the ions are also fragmented. In this way, several different responses can be produced to provide additional information about the nature of the analyte substance and distinguish it from interferents.

Abstract: The present invention relates generally to the field of ion storage and analysis, in particular to a linear ion trap mass analyzer comprised by multiple columnar electrodes. High frequency voltages are applied on at least one of the columnar electrodes to form ion confining space, which mainly consists of two-dimensional quadrupole electric radial trapping field, and there is at least one through slot for ion ejection in at least one direction perpendicular to the axis of the ion trap, wherein an AC electric field superposition is applied to invoke dipole excitation. Opposite to the through slot, there is an elongated electrode for field adjusting between two columnar electrodes or inside the slit of one of the columnar electrodes mentioned above. The potential on the elongated electrode for field adjusting is set as the sum of a portion of the high frequency voltage which applied on one adjacent columnar electrode and a DC offset, which can be adjusted freely.

Abstract: A mass spectrometer is disclosed wherein an ion signal is split into a first and second signal. The first and second signals are multiplied by different gains and are digitised. Arrival time and intensity pairs are calculated for both digitised signals and the resulting time and intensity pairs are combined to form a high dynamic range spectrum. The spectrum is then combined with other corresponding spectra to form a summed spectrum.

Abstract: A mass analyzer is provided comprising a plurality of electrodes having apertures through which ions are transmitted. A plurality of pseudo-potential corrugations are created along the axis of the mass analyzer. The amplitude or depth of the pseudo-potential corrugations is inversely proportional to the mass to charge ratio of an ion. Transient DC voltages are applied to the electrodes in order to urge ions along the length of the mass analyzer. The amplitude of the transient DC voltages applied to the electrodes is increased with time and ions are caused to be emitted from the mass analyzer in reverse order of their mass to charge ratio. Two AC or RF voltages are applied to the electrodes. The first AC or RF voltage is arranged to provide optimal pseudo-potential corrugations while the second AC or RF voltage is arranged to provide optimal radial confinement of ions within the mass analyzer.

Abstract: When ions accumulated in the exit side end of ion guide are to be injected into ion trap as packets, the application of square wave high frequency voltage to ring electrode from main voltage generating unit is stopped. Once nearly all the ions have been injected into ion trap, the application of square wave high frequency voltage from main voltage generating unit to ring electrode is momentarily started, at which time the application of square wave high frequency voltage is started from a phase in the range of 90°±40° or 270°±40°. It is thereby possible to reduce the extent of spread of ions immediately after application of high frequency voltage and to improve the ion trapping efficiency.

Abstract: A mass spectrometer is disclosed comprising an ion mobility spectrometer or separator and an ion guide arranged downstream of the ion mobility spectrometer or separator. A plurality of axial potential wells are created in the ion guide so that ions received from the ion mobility spectrometer or separator become confined in separate axial potential wells. The potential wells maintain the fidelity and/or composition of ions received from the ion mobility spectrometer or separator. The potential wells are translated along the length of the ion guide.

Abstract: An electrostatic Kingdon ion trap in which ions can oscillate harmonically in the longitudinal direction, decoupled from their motions in the transverse direction is formed from at least three inner electrodes located inside a hollow outer housing electrode. The inner surface of the housing electrode and the outer surfaces of the inner electrodes are formed so that when a potential is applied between the housing and the inner electrodes, the potential distribution inside the housing contains not only a term for a harmonic potential well in the axial direction, but also a term for the potential distribution in the radial direction, that contains, independent of the axial coordinate, the equations for a family of Cassini curves of at least the third order.

Abstract: A mass spectrometer is disclosed comprising a first storage ion trap arranged upstream of a high performance analytical ion trap. According to an embodiment ions are simultaneously scanned from both the first and second ion trap. At any instant in time the quantity of charge present within the second ion trap is limited or restricted so that the second ion trap does not suffer from space charge saturation effects and hence the performance of the second ion trap is not degraded.

Abstract: 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 hypologarithmic 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 Tm.

Abstract: A mass spectrometer is disclosed comprising a RF ion guide wherein in a mode of operation a continuous, quasi-continuous or pulsed beam of ions is orthogonally sampled from the ion guide and wherein the continuous, quasi-continuous or pulsed beam of ions is not axially trapped or otherwise axially confined within the RF ion guide. The ion guide is maintained, in use, at a pressure selected from the group consisting of: (i) 0.0001-0.001 mbar; (ii) 0.001-0.01 mbar; (iii) 0.01-0.1 mbar; (iv) 0.1-1 mbar; (v) 1-10 mbar; (vi) 10-100 mbar; and (vii) >100 mbar.

Abstract: Disclosed is a quadrupole mass spectrometer, which is capable of, during an SIM measurement, maximally reducing a settling time-period necessary for an operation of changing an input voltage to a quadrupole mass filter in a staircase pattern, and preventing unwanted ions from excessively entering a detector during a course of changing between a plurality of mass values. Under a condition that a response speed of a DC voltage U to be applied to quadrupole electrodes is less than that of an amplitude of a high-frequency voltage V, a control section 10 is operable to rearrange the mass values in descending order of mass value, and an optimal settling-time calculation sub-section 101 is operable to determine a settling time-period for each of the mass values, based on a mass-value difference and a post-change mass value.

Abstract: An RF transformer for supplying power as part of a tank circuit, comprising: a primary side, having at least one main winding and at least one shorting winding, the at least one main winding being configured to receive an RF input; a secondary side, having a first winding inductively coupled to the at least one main winding of the primary side and a second winding inductively coupled to the at least one shorting winding of the primary side; and a switching arrangement, adjustable between a first state in which the at least one shorting winding of the primary side is shorted and a second state in which the at least one shorting winding of the primary side is not shorted, such that the resonant frequency of the tank circuit is changed by adjusting between the first and second states.

Abstract: Disclosed is a quadrupole mass spectrometer, which is capable of, during an SIM measurement, maximally reducing a settling time-period necessary for an operation of changing an input voltage to a quadrupole mass filter in a staircase pattern, and preventing unwanted ions from excessively entering a detector during a course of changing between a plurality of mass values. Under a condition that a response speed of a DC voltage U to be applied to quadrupole electrodes is less than that of an amplitude of a high-frequency voltage V, a control section 10 is operable to rearrange the mass values in descending order of mass value, and an optimal settling-time calculation sub-section 101 is operable to determine a settling time-period for each of the mass values, based on a mass-value difference and a post-change mass value.

Abstract: An ion trap for a mass spectrometer has a conductive central electrode with an aperture extending from a first open end to a second open end. A conductive first electrode end cap is disposed proximate to the first open end thereby forming a first intrinsic capacitance between the first end cap and the central electrode. A conductive second electrode end cap is disposed proximate to the second open end thereby forming a second intrinsic capacitance between the second end cap and the central electrode. A first circuit couples the second end cap to a reference potential. A signal source generating an AC trap signal is coupled to the central electrode. An excitation signal is impressed on the second end cap in response to a voltage division of the trap signal by the first intrinsic capacitance and the first circuit.

Abstract: An orthogonal ion injection apparatus and process are described in which ions are directly injected into an ion guide orthogonal to the ion guide axis through an inlet opening located on a side of the ion guide. The end of the heated capillary is placed inside the ion guide such that the ions are directly injected into DC and RF fields inside the ion guide, which efficiently confines ions inside the ion guide. Liquid droplets created by the ionization source that are carried through the capillary into the ion guide are removed from the ion guide by a strong directional gas flow through an inlet opening on the opposite side of the ion guide. Strong DC and RF fields divert ions into the ion guide. In-guide orthogonal injection yields a noise level that is a factor of 1.5 to 2 lower than conventional inline injection known in the art. Signal intensities for low m/z ions are greater compared to convention inline injection under the same processing conditions.

Abstract: A system and method of mass spectrometry is provided. Ions from an ion source are stored in a first ion storage device and in a second ion storage device. Ions are ejected from the first ion storage device to a first mass analysis device during a first ejection time period, for analysis during a first analysis time period. Ions are ejected from the second ion storage device to a second mass analysis device during a second ejection time period. The ion storage devices are connected in series such that an ion transport aperture of the first ion storage device is in communication with an ion transport aperture of the second ion storage device. The first analysis time period and the second ejection time period at least partly overlap.

Abstract: Apparatus and methods are provided that enable the interaction of low energy electrons and positrons with sample ions to facilitate electron capture dissociation (EGO) and positron capture dissociation (PGO), respectively, within multipole ion guide structures. The apparatus and methods described herein allow EGO (and PCO) to be performed within multipole ion guides, either alone, or in combination with conventional ion fragmentation methods.

Abstract: An object of the present invention is to provide means for solving troubles. Examples of the troubles include sensitivity degradation and resolution degradation of a mass spectrometer, which are caused by an axis deviation of a component, particularly at least one orifice located between an ion source and a detector, to decrease the number of ions reaching the detector, and a variation in performance caused by exchange of components such as the orifice. For example, the invention has the following configuration in order to solve the troubles. A mass spectrometer includes: an ion source; a detector that detects an ion; an orifice and a mass separator that are disposed between the ion source and the detector; and an axis adjusting mechanism that adjusts axis positions of the orifice and/or the mass separator such that an opening of the orifice and/or an incident port of the mass separator is disposed on a line connecting the ion source and an incident port of the detector.

Abstract: A method of processing a plurality of image charge/current signals representative of trapped ions undergoing oscillatory motion, e.g. for use in an ion trap mass spectrometer. The method includes producing a linear combination of the plurality of image charge/current signals using a plurality of predetermined coefficients, the predetermined coefficients having been selected so as to suppress at least one harmonic component of the image charge/current signals within the linear combination of the plurality of image charge/current signals.

Abstract: An ion guide is disclosed comprising a plurality of axial groupings of electrodes, wherein each axial grouping of electrodes comprises a ring or annular electrode which has been radially segmented into a plurality of electrode segments.

Abstract: When an SIM measurement for ions originating from a target component separated by a chromatograph is performed, the measurement is performed while the mass-resolving power is switched among a plurality of levels of resolving power, with the mass-to-charge ratio fixed at a target value (S2), and an extracted ion chromatogram is created based on each of data obtained corresponding to respective mass-resolving powers (S3). After the extracted ion chromatograms are obtained, an S/N ratio is calculated for a peak of the target component on each of the chromatograms (S4), and a mass-resolving power which yields the highest S/N ratio is selected (S5). The selected mass-resolving power is set as the mass-resolving power in the subsequent measurements of the same target component in the same kind of sample (S6), and the quantitative determination of the target component is performed using the extracted ion chromatogram obtained with the selected mass-resolving power (S7).

Abstract: In order to provide an analysis method that is capable of determining a glycan structure with high detection sensitivity, a method of the present invention includes the steps of: carrying out triple quadrupole mass spectrometry at various values of CID energy; creating an energy-resolved profile including yield curves representing relationships between (i) a value of the CID energy and (ii) measured amounts of specific types of product ions; preparing a reference profile, and identifying a glycan structure of a test material by comparing the energy-resolved profile with the reference profile.

Abstract: A combination of electrodes that are cylindrical and an asymmetric arrangement of cylindrical and planar electrodes are used to create electric fields that compensate for toroidal curvature in a toroidal ion trap, the design lending itself to high precision manufacturing and miniaturization, converging ion paths that enhance detection, higher pressure operation, and optimization of the shape of the electric fields by careful arrangement of the electrodes.

Abstract: A mass spectrometer is disclosed comprising a quadrupole rod set ion trap wherein a potential field is created at the exit of the ion trap which decreases with increasing radius in one radial direction. Ions within the ion trap are mass selectively excited in a radial direction. Ions which have been excited in the radial direction experience a potential field which no longer confines the ions axially within the ion trap but which instead acts to extract the ions and hence causes the ions to be ejected axially from the ion trap.

Abstract: A device for use in a mass spectrometer allows an ion-optical assembly to be removed, cleaned and reinserted with relatively high positioning accuracy. In particular, the device obviates the need for complex adjustments requiring special knowledge after the reinsertion. The objective is achieved by an arrangement comprising a receptacle and a mount for a removable ion-optical assembly in a mass spectrometer. Favorable implementations provide a mount and a receptacle with three pairs of complementary support elements, the three support elements on the receptacle form a support plane, and, when the mount is inserted into the receptacle, at least two pairs of support elements are engaged and the mount is aligned with respect to the support plane with the aid of the third pair of support elements.

Abstract: A mass spectrometer is disclosed comprising a device which is operable in a first mode of operation to separate ions temporally according to their ion mobility by applying a continuous axial electric field. The device is also operable in a second mode of operation wherein ions are separated temporally according to the their mass to charge ratio by pulsing an applied axial electric field ON and OFF.

Abstract: A mass spectrum is acquired by accumulating parent ions in an ion trap, ejecting parent ions of a selected m/z ratio into a collision cell, producing fragment ions from the parent ions, and analyzing the fragment ions in a mass analyzer. The other parent ions remain stored in the ion trap, and thus the process may be repeated by mass-selectively scanning parent ions from the ion trap. In this manner, the full mass range of parent ions or any desired subset of the full mass range may be analyzed without significant ion loss or undue time expenditure. The collision cell may provide a large ion acceptance aperture and relatively smaller ion emission aperture. The collision cell may pulse ions out to the mass analyzer. The mass analyzer may be a time-of-flight analyzer. The timing of pulsing of ions out from the collision cell may be matched with the timing of pulsing of ions into the time-of-flight analyzer.

Abstract: A collision or fragmentation cell is disclosed comprising a plurality of electrodes wherein a first RF voltage is applied to an upstream group of electrodes and a second different RF voltage is applied to a downstream group of electrodes. The radial confinement of parent ions entering the collision or fragmentation cell is optimized by the first RF voltage applied to the upstream group of electrodes and the radial confinement of daughter or fragment ions produced within the collision or fragmentation cell is optimized by the second different RF voltage applied to the downstream group of electrodes.

Abstract: An ion trap for a mass spectrometer is disclosed. The ion trap includes a ring electrode and first and second electrodes which are arranged on opposite sides of the ring electrode. The ring electrode and the first and second electrodes are configured to generate an electric field based on the received RF signal. The first electrode defines a first aperture and the second electrode defines a second aperture, the first aperture and the second aperture being asymmetric relative to each other and configured to generate a hexapole field.

Abstract: An apparatus includes an atmospheric pressure ion source; a first vacuum stage and a second vacuum stage separated from the first vacuum stage by a vacuum partition; a first ion guide positioned within a first vacuum stage and arranged to receive ions from the atmospheric pressure ion source; a second ion guide positioned within a second vacuum stage downstream of the first vacuum stage from the atmospheric pressure ion source, the second ion guide being a multipole ion guide arranged to receive ions from the first ion guide; and a time-of-flight mass analyzer that includes an orthogonal pulsing region arranged to receive ions from the second ion guide.

Abstract: An inductively coupled plasma MS/MS mass analyzer (ICP-MS/MS) may include a first vacuum chamber which draws plasma containing an ionized sample into vacuum, a second vacuum chamber which includes a device or means which extracts and guides ions as an ion beam from the ions output from the first vacuum chamber, a third vacuum chamber which has a first ion optical separation device or means, a fourth vacuum chamber which has a cell into which reaction gas is introduced, and a fifth vacuum chamber which has a second optical separation device or means and a detector, wherein the second vacuum chamber and third vacuum chamber are individually evacuated.

Abstract: A sensor assembly for electric field sensing is provided. The sensor assembly may include an array of Micro-Electro-Mechanical System (MEMS)-based resonant tunneling devices. A resonant tunneling device may be configured to generate a resonant tunneling signal in response to the electric field. The resonant tunneling device may include at least one electron state definer responsive to changes in at least one respective controllable characteristic of the electron state definer. The changes in the controllable characteristic are configured to affect the tunneling signal. An excitation device may be coupled to the resonant tunneling device to effect at least one of the changes in the controllable characteristic affecting the tunneling signal. A controller may be coupled to the resonant tunneling device and the excitation device to control the changes of the controllable characteristic in accordance with an automated control strategy configured to reduce an effect of noise on a measurement of the electric field.

Abstract: A spectrometer is offered which can reduce ion loss compared with the prior art even when ions selected by the mass analyzer are modified. The spectrometer includes an ion source for ionizing a sample, an ion storage portion for repeatedly performing a storing operation for storing ions created by the ion source and an expelling operation for expelling the stored ions as pulsed ions, the mass analyzer for passing pulsed ions expelled from the ion storage portion and selecting desired ions according to their mass-to-charge ratio, a detector for detecting pulsed ions passed through the mass analyzer and outputting an analog signal responsive to the intensity of the detection, and a controller for maintaining constant the mass-to-charge ratio of the desired ions selected by the mass analyzer while pulsed ions including the desired ions are passing through the mass analyzer.

Abstract: The present invention relates to the analytical electronics used to identify compositions and structures of substances, in particular, to the analyzers comprising at least one mass-spectrometer (MS) and may be applied in such fields as medicine, biology, gas and oil industry, metallurgy, energy, geochemistry, hydrology, ecology. Technical result provides the increase in MS resolution, gain in sensitivity, precision and measurement rates of substances compositions and structures concurrently with enhancement of analyzer functional capabilities, downsizing and mass reduction. In claimed invention the ion flux generation and its guiding are performed in off-axis single-flow mode; parallel multi-stage mode; through use of three-dimensional field with mean meridian surface including without limitation three-dimensional reflecting and dual-zoned reflecting modes or by method of multi-reflection arrays. Devices to implement the claimed method are embodied.

Abstract: A mass spectrometer is disclosed comprising a time of flight mass analyzer. The time of flight mass analyszr comprises an ion guide comprising a plurality of electrodes which are interconnected by a series of resistors forming a potential divider. Ions are confined radially within the ion guide by the application of a two-phase RF voltage to the electrodes. A single phase additional RF voltage is applied across the potential divider so that an inhomogeneous pseudo-potential force is maintained along the length of the ion guide.

Abstract: A method includes directing ions from an atmospheric pressure ion source to a first ion guide; directing ions in the first ion guide to a second ion guide, the second ion guide being a multipole ion guide extending along an axis; periodically directing ions along the axis; receiving at least some of the ions in a time-of-flight analyzer; accelerating the ions in the time-of-flight mass analyzer orthogonal to the axis; and detecting the accelerated ions.

Abstract: This invention relates generally to multi-reflection electrostatic systems, and more particularly to improvements in and relating to the Orbitrap electrostatic ion trap. A method of operating an electrostatic ion trapping device having an array of electrodes operable to mimic a single electrode is proposed, the method comprising determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode, and applying the three or more so determined voltages to the respective electrodes. Further improvements lie in measuring a plurality of features from peaks with different intensities from one or more collected mass spectra to derive characteristics, and using the measured characteristics to improve the voltages to be applied to the plurality of electrodes.

Abstract: A linear ion trap is disclosed wherein an asymmetric voltage waveform is applied to electrodes forming the ion trap which causes ions to become radially separated according to their differential ion mobility. An axial potential barrier is arranged at the exit of the ion trap such that ions having a first differential ion mobility and a first radial displacement are retained axially within the ion trap but ions having a second differential ion mobility and a second radial displacement are ejected axially from the ion trap.

Abstract: A method of operating a gas-filled collision cell in a mass spectrometer is provided. The collision cell has a longitudinal axis. Ions are caused to enter the collision cell. A trapping field is generated within the collision cell so as to trap the ions within a trapping volume of the collision cell, the trapping volume being defined by the trapping field and extending along the longitudinal axis. Trapped ions are processed in the collision cell and a DC potential gradient is provided, using an electrode arrangement, resulting in a non-zero electric field at all points along the axial length of the trapping volume so as to cause processed ions to exit the collision cell. The electric field along the axial length of the trapping volume has a standard deviation that is no greater than its mean value.

Abstract: An ion trap includes an electrode structure, including a first and a second opposed mirror electrodes and a central lens therebetween, that produces an electrostatic potential in which ions are confined to trajectories at natural oscillation frequencies, the confining potential being anharmonic. The ion trap also includes an AC excitation source having an excitation frequency f that excites confined ions at a frequency of about twice the natural oscillation frequency of the ions, the AC excitation frequency source preferably being connected to the central lens. In one embodiment, the ion trap includes a scan control that mass selectively reduces a frequency difference between the AC excitation frequency and about twice the natural oscillation frequency of the ions.

Abstract: The present invention provides a radio frequency (RF) power supply in a mass spectrometer. The power supply provides an RF signal to electrodes of a storage device to create a trapping field. The RF field is usually collapsed prior to ion ejection. In an illustrative embodiment the RF power supply includes a RF signal supply; a coil arranged to receive the signal provided by the RF signal supply and to provide an output RF signal for supply to electrodes of an ion storage device; and a shunt including a switch operative to switch between a first open position and a second closed position in which the shunt shorts the coil output.