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.

The invention provides a mass spectrometer, an ion optical device, and a method for ion manipulation in a mass spectrometer. The mass spectrometer includes a mass analyzer; and an ion guiding device, including two electrode arrays positioned in parallel with each other, each electrode array including at least two ring electrodes concentrically disposed or at least three linear electrode assemblies having a radial distribution; and a power supply means, configured to apply a voltage on at least a part of the ring electrodes, to form a radio-frequency electric field and a DC electric field. By means of the radio-frequency electric field and the DC electric field, ions are allowed to be stored in a region between the two arrays, and controlled to be sequentially released along a radial direction according to a preset mass-to-charge ratio requirement, then exit the ion guiding device and enter the mass analyzer for mass analysis.

In a linear ion trap (3), the shape and arrangement of four rod electrodes (3a-3d) are made to deviate from an ideal state in which only a quadrupole electric field is created, in such a manner that so that the polarity of the ratio of the strength of an octapole electric field to the strength of the quadrupole electric field is different from the polarity of the ratio of the strength of an dodecapole electric field to the strength of the quadrupole electric field, where the absolute value of each of the ratios is equal to or greater than 0.005, and the absolute value of the ratio of the strength of the octapole electric field to the strength of the dodecapole electric field is within a range from 0.5 to 1.4. By superposing the octapole electric field on the quadrupole electric field and additionally superposing the dodecapole electric field having the opposite polarity to the octapole electric field, a peak shift of a resonance curve can be canceled and a peak having a steep edge on both high-frequency and low-frequency sides can be obtained. A linear ion trap satisfying those conditions can achieve both high ion-trapping efficiency and high ion-separating power.

In one aspect, a mass spectrometer is disclosed, which comprises an ion trap having a plurality of electrodes arranged in a multipole configuration so as to provide an inlet for receiving ions along a longitudinal axis into a space between the electrodes, where at least one of the plurality of electrodes comprises a passageway through which ions can be extracted radially from the ion trap. The electrodes are configured for application of one or more RF voltages thereto for providing radial confinement of the ions, and a DC voltage source configured to apply a dipolar DC voltage pulse across said at least one electrode and an opposed electrode for causing radial extraction of at least a portion of said ions from said ion trap through said passageway.

A method for driving a linear ion trap having rod electrodes arranged so as to surround a central axis includes: an ion-introducing step for introducing ions into an ion-capturing space surrounded by the rod electrodes, and for capturing the ions by a multipole RF electric field created within the ion-capturing space; and an ion-ejecting step for creating both a DC electric field for ion extraction extending from an external area outside the ion-capturing space into the ion-capturing space through a space between two predetermined rod electrodes neighboring each other around the central axis among the plurality of rod electrodes and the multipole RF electric field, and for sequentially ejecting ions according to their m/z from the ion-capturing space toward the external area through the space between the two predetermined rod electrodes by changing at least one of the multipole RF electric field and the DC electric field.

An apparatus for separating ions includes an electrode arrangement having a length extending between first and second ends. The first end is configured to introduce a beam of ions into an ion transmission space of the arrangement. An electronic controller applies an RF potential and a DC potential to an electrode of the electrode arrangement, for generating a ponderomotive RF electric field and a mass-independent DC electric field. The application of the potentials is controlled such that a ratio of the strength of the ponderomotive RF electric field to the strength of the mass-independent DC electric field varies along the length of the electrode arrangement. The generated electric field supports extraction of ions having different m/z values at respective different positions along the length of the electrode arrangement. Ions are extracted in one of increasing and decreasing sequential order of m/z ratio with increasing distance from the first end.

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.

The ion trap comprises a multipole electrode assembly, a first confining electrode, and a second confining electrode. The multipole electrode assembly is configured to confine ions of the first polarity to an ion channel extending in an axial direction of the multipole electrode assembly. The first confining electrode is provided adjacent to the multipole electrode assembly and extends in the axial direction of the multipole electrode assembly. The second confining electrode is provided adjacent to the multipole electrode assembly and extends in the axial direction of the multipole electrode assembly aligned with the first confining electrode. The first and second confining electrodes are spaced apart in the axial direction in order to define an ion confining region of the ion channel between the first and second confining electrodes. The first and second confining electrodes are configured to receive a DC potential of the first polarity to further confine ions within the ion channel in the ion confining region.

An apparatus for separating ions includes an electrode arrangement having a length extending between first and second ends. The first end is configured to introduce a beam of ions into an ion transmission space of the arrangement. An electronic controller applies an RF potential and a DC potential to an electrode of the electrode arrangement, for generating a ponderomotive RF electric field and a mass-independent DC electric field. The application of the potentials is controlled such that a ratio of the strength of the ponderomotive RF electric field to the strength of the mass-independent DC electric field varies along the length of the electrode arrangement. The generated electric field supports extraction of ions having different m/z values at respective different positions along the length of the electrode arrangement. Ions are extracted in one of increasing and decreasing sequential order of m/z ratio with increasing distance from the first end.

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.