A mass spectrometer comprising: an ion energy filter 14 arranged and configured to filter ions according to their kinetic energy and so as to only transmit ions having a component of kinetic energy in a first dimension (z-dimension) that is within a selected range; and a multi-reflecting time of flight mass analyser or mass separator 1 having an ion accelerator 6, and two gridless ion mirrors 2 that are elongated in the first dimension (z-dimension) and configured to reflect ions multiple times in a second orthogonal dimension (x-dimension), wherein the ion accelerator 6 is arranged to receive ions from the energy filter 14 and accelerate the ions into one of the ion mirrors 2.

A transfer electrode unit (240) is configured by coaxially arranging a plurality of loop electrodes (241A, 241B, 241C), and guides ions to an orthogonal acceleration region (242C) by allowing the ions to pass through an inner side of the plurality of electrodes (241A, 241B, 241C) each of which is applied with a voltage. A voltage having a higher absolute value than the voltage applied to the plurality of electrodes (241A, 241B, 241C) is applied to a flight tube (246), and the ions accelerated in the orthogonal acceleration region (242C) are introduced to a flight space formed in the flight tube (246). A shield portion (241F) is provided between the transfer electrode unit (240) and the flight tube (246), and suppresses that an electric field derived from the voltage applied to the flight tube (246) enters the transfer electrode unit (240).

A multi-pass time-of-flight mass spectrometer is disclosed having an elongated orthogonal accelerator (30). The orthogonal accelerator (30) has electrodes (31) that are transparent to the ions so that ions that are reflected or turned back towards it are able to pass through the orthogonal accelerator (30). The electrodes (31) of the orthogonal accelerator (30) may be pulsed from ground potential in order to avoid the reflected or turned ion packets being defocused. The spectrometer has a high duty cycle and/or space charge capacity of pulsed conversion.

A lead-in electrode, of an orthogonal acceleration time-of-flight mass spectrometer, includes: a main body having an ion passing part and a first member including a main-body accommodating part that is a through-hole. One surface of the first member includes an extension part to define a position of one surface of the main body. A second member is attached to the first member. A through-hole is provided at a position of the second member. One surface of the second member includes a first area in contact with a surface opposite to the one surface of the first member and a second area located inside with respect to the first area. The second area is formed lower than a surface, of the first area, in contact with the surface opposite to the one surface. A lead-in electrode elastic member is disposed, in the second area, between the first member and second members.

In a tandem mass spectrometer, when the measurement mode is switched between a positive ion measurement mode and a negative ion measurement mode, a DC offset voltage applied to a lens electrode to impart collision energy to an ion is temporarily switched to 0V (S1). After being maintained at 0V for a predetermined waiting time (S2), the voltage is changed to a DC offset voltage corresponding to a measurement mode which is used after the switching operation (S3). By such an operation, the voltage difference between the neighboring plate electrodes among the plate electrodes (171, 172, 173) included in the lens electrode can be decreased as compared to the case where the polarity of the DC offset voltage is immediately switched. Consequently, unintended electric discharge between the neighboring electrodes can be prevented.

A multipole ion guide (30) including a plurality of rod electrodes arranged at an angle to the central axis (C) is placed within a collision cell (13) located in the previous stage of an orthogonal accelerator (16). Radio-frequency voltages with opposite phases are applied to the rod electrodes of the ion guide (30) so that any two rod electrodes neighboring each other in the circumferential direction have opposite phases of the voltage. A depth gradient of the pseudopotential is thereby formed from the entrance end toward the exit end within the space surrounded by the rod electrodes, and ions are accelerated by this gradient. During an ion-accumulating process, a direct voltage having the same polarity as the ions is applied to the exit lens electrode (132) to form a potential barrier for accumulating ions. Among the ions repelled by the potential barrier, ions having smaller m/z return closer to the entrance end. Therefore, when the potential barrier is removed and ions are discharged, ions having smaller m/z are discharged at later points in time than those having larger m/z. Therefore, a wide m/z range of ions can be simultaneously accelerated and ejected by an orthogonal accelerator (16).

A MALDI ion source for tandem mass spectrometers includes a pulsed energy source that generates a pulse of ions from a sample on a sample plate. An ion accelerator includes an input that receives the pulse of ions from the pulsed energy source and generates an electric field that accelerates the pulse of ions. An ion decelerator that generates an electric field that is a mirror image of the electric field generated by the ion accelerator that accelerates the pulse of ions so that the ion decelerator decelerates the accelerated pulse of ions and transmits the decelerated pulse of ions through an exit aperture.

An analytical device includes: a first acceleration unit including a first acceleration electrode to which a pulse voltage for accelerating ions is applied; a flight tube; a second acceleration unit that is arranged between the first acceleration unit and the flight tube, and includes a second acceleration electrode to which a voltage for accelerating the ions is applied; an ion detector that detects the ions; and a capacitance adjustment unit that causes adjustment of a capacitance between at least one set of electrodes among a plurality of electrodes arranged in the first acceleration unit, the second acceleration unit, and a flight tube.

Apparatus and method are proposed for the strong improvement of dynamic range (DR) of detectors and of data systems for time-of-flight mass spectrometers (TOF MS) with periodically repetitive signals. TOF separated ions are converted into secondary particles, primarily electrons, and the flow of secondary particles is controllably attenuated to sustain the data acquisition system in a counting mode above the electronic noise threshold. The acquisition time is split between at least two time segments, characterized by alternated transmission efficiency SE of secondary particles. Using strong electron suppression (SE1) is employed for recording intense ion peak, while counting ions with either ADC, or TDC, or ADC with extracting peak centroids. A longer time segment employs an efficient electron transfer (SE=1) for detecting weak ion species. In another independent aspect, an ion-optical element is provided upstream of the ion detector and is configured to deflect, reflect or retard ions such that ions that have been scattered or fragmented in the time of flight region do not impact on the ion detector.

A drive unit for driving an acceleration electrode of amass spectrometer is disclosed. The drive unit includes a power converter comprising a switching element and pulsing circuitry that can form output pulses suitable for driving an acceleration electrode of amass spectrometer. The drive unit also includes a controller that is configured to synchronise operation of the switching element with the pulsing circuitry.