An MT-TOFMS which is one mode of the present invention includes: a linear ion trap (2) configured to temporarily hold ions to be analyzed, and to eject the ions through an ion ejection opening (211) having a shape elongated in one direction; a loop flight section (3) configured to form a loop path (P) capable of making ions repeatedly fly; and a slit part (5) located on an ion path in which the ions ejected from the linear ion trap (2) travel until the ions are introduced into the loop path, the slit part configured to block a portion of the ions in a longitudinal direction of the ion ejection opening (211).

An octa-electrode linear ion trap mass analyzer is formed by eight cylindrical electrodes and at least two end-cap electrodes. The inside surfaces of the eight cylindrical electrodes are free-form. The material of the octa-electrode linear ion trap mass analyzer is a conductive metal material or an insulating material plated with a conductive coating. The eight cylindrical electrodes are divided into four groups of cylindrical electrodes in total, each group of the four groups of cylindrical electrodes comprises two cylindrical electrodes, and each two groups of the four groups of cylindrical electrodes are parallelly placed. At least one through hole is provided with in the center of the end-cap electrode, and the two end-cap electrodes are respectively arranged at both ends of the cylindrical electrode.

A mass selective ion trapping device includes a linear ion trap and a RF control circuitry. The ion trap includes a plurality of trap electrodes configured for generating a quadrupolar trapping field in a trap interior and for mass selective ejection of ions from the trap interior. The RF control circuitry is configured to apply a balanced AC voltage to the trap electrodes during a first period of time such that an AC voltage applied to a first pair of trap electrodes is of the same magnitude and of opposite sign to an AC voltage applied to a second pair of trap electrodes; apply unbalanced RF voltage to the second pair of trap electrodes during a second period of time; ramp the balanced AC voltage down and the unbalanced RF voltage up during a transition period; and eject ions from the linear ion trap after the second period of time.

A method of injecting ions into an ion storage device, comprising: providing an RF trapping field in the ion storage device that defines a trapping volume in the ion storage device by applying one or more RF voltages to one or more trapping electrodes; providing a gas in the trapping volume; injecting ions into the trapping volume through an aperture in an end electrode located at a first end of the ion storage device, the end electrode having a DC voltage applied thereto; reflecting the injected ions at a second end of the ion storage device, opposite to the first end, thereby returning the ions to the first end; and ramping the DC voltage applied to the end electrode during the period between injecting the ions through the aperture and the return of the ions to the first end, such that by the time the ions return to the first end for a first time a potential barrier is established by the ramped DC voltage that prevents returning ions from striking the end electrode. Also an apparatus for injecting ions into an ion storage device, which comprises a controller for ramping a first DC voltage applied to an end electrode of the device having an entrance aperture during a period between injection of ions through the entrance aperture and a return of the injected ions to the aperture so as to establish a potential barrier that prevents returning ions from striking the end electrode.

A mass selective ion trapping device includes a linear ion trap and a RF control circuitry. The ion trap includes a plurality of trap electrodes configured for generating a quadrupolar trapping field in a trap interior and for mass selective ejection of ions from the trap interior. The RF control circuitry is configured to apply a balanced AC voltage to the trap electrodes during a first period of time such that an AC voltage applied to a first pair of trap electrodes is of the same magnitude and of opposite sign to an AC voltage applied to a second pair of trap electrodes; apply unbalanced RF voltage to the second pair of trap electrodes during a second period of time; ramp the balanced AC voltage down and the unbalanced RF voltage up during a transition period; and eject ions from the linear ion trap after the second period of time.

In one aspect, an ion trap is disclosed, which includes a curved linear ion trap having a plurality of electrodes arranged around a central curved axis so as to provide a volume for trapping ions, said plurality of electrodes comprising at least one inner electrode and at least one outer electrode radially separated from said inner electrode. The ion trap further includes a pair of inner and outer ion guide electrodes providing a volume therebetween for receiving ions ejected from said curved ion trap and guiding the ejected ions to one or more spatial locations along a focal line, said inner and outer ion guide electrodes being positioned external to said ion trapping volume and in proximity of said at least inner and outer electrodes of the curved ion trap, respectively, wherein a DC voltage is applied between said ion guide electrodes to provide an electric filed therebetween for guiding the ejected ions to said spatial locations.

A mass selective ion trapping device includes a linear ion trap and a RF control circuitry. The ion trap includes a plurality of trap electrodes configured for generating a quadrupolar trapping field in a trap interior and for mass selective ejection of ions from the trap interior. The RF control circuitry is configured to apply a balanced AC voltage to the trap electrodes during a first period of time such that an AC voltage applied to a first pair of trap electrodes is of the same magnitude and of opposite sign to an AC voltage applied to a second pair of trap electrodes; apply unbalanced RF voltage to the second pair of trap electrodes during a second period of time; ramp the balanced AC voltage down and the unbalanced RF voltage up during a transition period; and eject ions from the linear ion trap after the second period of time.

Provided is a mass spectrometer which repeats the operation of capturing ions originating from a sample component into an ion trap (22), ejecting the ions from the ion trap, and analyzing the ions with a TOF mass analyzer (23). A capturing voltage generator (51) applies an ion-capturing radio-frequency voltage to the ion trap. An ejecting voltage generator (52) applies an ion-ejecting voltage whose phase is synchronized with the radio-frequency voltage. A controller (4) controls those devices to introduce next ions to be analyzed into the ion trap while performing a mass spectrometric analysis in the TOF mass analyzer. A blank signal acquirer (4, 32) acquires a blank signal within a measurement period or measurement window while the ion trap is being operated. A noise remover (33) subtracts blank-signal data from signal intensity data acquired by a sample measurement. A spectrum creator (34) creates a mass spectrum based on noise-removed data.

An ion trap 1 comprises one ejection electrode 2 for ion trapping having an opening 4, through which ions in the ion trap 1 can be ejected in an ejection direction E and further electrodes 3 for ion trapping, wherein the ejection electrode 2 and the further electrodes 3 are elongated in a longitudinal direction L. The angle between the longitudinal direction L and the ejection direction E is nearly 90. The ion trap 1 comprises a primary winding 5 connected to an RF power supply 6, a secondary winding 7 coupling with the primary winding 5 for transforming the RF voltage of the RF power supply 6 supplying the transformed RF signals to the ejection electrode 2 and secondary windings 7 coupling with the primary winding 5 for transforming the RF voltage of the RF power supply 6 supplying the transformed RF signals to the further electrodes 3. The ion trap 1 comprises a first DC supply 8, a second DC supply 9 and a controller 50, which is applying in a time period a first DC voltage provided by first DC supply 8 via the secondary winding 7 to the ejection electrode 2 to pull ions in the ion trap to the opening 4 of the ejection electrode 2 and a second DC voltage provided by the second DC supply 9 via the secondary windings 7 to the at least 70% of the further electrodes 3 to push ions in the ion trap to the opening 4 of the ejection electrode 2.

Conversion dynodes (CDs) 31 and 32 are respectively provided for ion-ejection ports 21a and 22a facing each other across the central axis C of a linear ion trap (LIT) 2. A shield plate 34 having ion-passage openings 34a is provided between LIT and CDs. A voltage slightly lower than the voltage applied to CDs is applied to the shield plate. Ions ejected from LIT by resonant excitation are accelerated by an electric field between LIT and the shield plate, having their trajectories gradually curved, to eventually reach CDs through the ion-passage openings. Upon receiving the ions, CDs emit electrons. Some electrons may initially move toward the shielding plate, but will be repelled to and detected by an electron multiplier tube 33. CDs can be made of aluminum or similar inexpensive materials, which reduces the cost as well as eliminates the loss of the ions and improves detection sensitivity.