CN-121983500-A - Magnetic-electric coupling focusing ion transmission device

CN121983500ACN 121983500 ACN121983500 ACN 121983500ACN-121983500-A

Abstract

The invention relates to the technical field of mass spectrometry, in particular to a magnetic-electric coupling focusing ion transmission device. The device comprises a front-end differential electrode, a circular vacuum cavity, a rear-end differential electrode, a radio frequency multipole rod, a guide magnetic ring and a focusing magnetic ring, wherein the front-end differential electrode and the rear-end differential electrode are respectively connected with openings at two ends of the circular vacuum cavity, the guide magnetic ring and the focusing magnetic ring are axially arranged in the circular vacuum cavity, the radio frequency multipole rod comprises at least four rod-shaped electrodes which encircle the focusing magnetic ring, the guide magnetic ring and the focusing magnetic ring respectively generate a first second axial magnetic field, the focusing magnetic ring and the radio frequency multipole rod are axially overlapped, so that the second axial magnetic field and a radial focusing electric field generated by the radio frequency multipole rod are spatially overlapped and coupled, and direct-current voltages are applied to the electrodes. According to the invention, through the synergistic effect of the axial magnetic field and the radio frequency electric field, the radial divergence of the ion beam under the conditions of high pressure difference and high density is strongly restrained, and the efficient transmission of the ion beam in a wide mass range is realized.

Inventors

LI HAIYANG
FAN ZHIGANG
HUA LEI
JIANG JICHUN
Ruan Huiwen
YANG MING

Assignees

中国科学院大连化学物理研究所

Dates

Publication Date: 20260505
Application Date: 20260129

Claims (10)

1. The magneto-electric coupling focusing ion transmission device is characterized by comprising a front-end differential electrode (1), a circular vacuum cavity (2), a rear-end differential electrode (3), a radio frequency multipole rod (4), a guide magnetic ring (5) and a focusing magnetic ring (6), wherein the circular vacuum cavity (2) is of a cylindrical structure which is horizontally arranged and is provided with two open ends, and the front-end differential electrode (1) and the rear-end differential electrode (3) are of circular flat plate structures with central holes and are respectively connected with the two open ends of the circular vacuum cavity (2) in a sealing insulation manner; The guide magnetic ring (5) and the focusing magnetic ring (6) are axially arranged in the circular vacuum cavity (2), and the guide magnetic ring (5) is arranged close to the front differential electrode (1); the radio frequency multipole rod (4) comprises at least four rod-shaped electrodes which encircle the outer side of the focusing magnetic ring (6); The focusing magnetic ring (6) is used for generating a second axial magnetic field, and the magnetic field strength of the second axial magnetic field is larger than that of the first axial magnetic field; The focusing magnetic ring (6) and the radio frequency multipole rod (4) are at least partially overlapped in the axial direction, so that the second axial magnetic field and the radial focusing electric field generated by the radio frequency multipole rod (4) are coupled in a space overlapping manner; And direct-current voltage is applied to each rod-shaped electrode in the front-end differential electrode (1), the rear-end differential electrode (3) and the radio-frequency multipole rod (4).
2. The magneto-electric coupling focused ion transmission device according to claim 1, wherein the axes of the front-end differential electrode (1), the rear-end differential electrode (3), the radio-frequency multipole rod (4), the guide magnetic ring (5) and the focusing magnetic ring (6) are all collinear with the axis of the circular vacuum cavity (2), and the circle centers of all rod-shaped electrodes in the radio-frequency multipole rod (4) are uniformly distributed on the same circumference.
3. The magneto-electric coupling focused ion transmission device according to claim 1, wherein the radio frequency multipole rod (4) is a quadrupole rod, a hexapole rod or an octapole rod, wherein the rod-shaped electrodes are identical in structure, have a length of 90-200mm and have a diameter of 9-16mm.
4. The magneto-electric coupling focused ion transport device according to claim 1, wherein the front-end differential electrode (1) has a thickness of 2-6mm and a center hole diameter of 0.1-2mm, the rear-end differential electrode (3) has a thickness of 2-4mm and a center hole diameter of 2-4mm; Each rod-shaped electrode in the front-end differential electrode (1), the rear-end differential electrode (3) and the radio frequency multipole rod (4) is made of a conductive metal material or a material with a surface plated with a conductive metal layer.
5. The magneto-electric coupling focused ion transport device of claim 1, wherein the guide magnet ring (5) and the focusing magnet ring (6) are both permanent magnet rings.
6. The magneto-electric coupling focused ion transport device of claim 1, wherein the guide magnetic ring (5) has a thickness of 15-40mm and an inner diameter of 10-16mm, the first axial magnetic field strength generated is 0.01T to 0.2T, the focusing magnetic ring (6) has a thickness of 15-40mm and an inner diameter of 6-10 mm, and the second axial magnetic field strength generated is 0.05T-1T.
7. The magneto-electric coupling focused ion transport device according to claim 1, wherein the dc voltage applied to the front-end differential electrode (1) is 100-400V, the dc voltage applied to each rod-like electrode in the radio frequency multipole rod (4) is 10-50V, the dc voltage applied to the rear-end differential electrode (3) is 10-20V, and the dc voltages decrease in sequence along the ion transport direction.
8. The magneto-electric coupling focused ion transport device of claim 1, wherein each rod-like electrode in the radio frequency multipole (4) is further applied with a radio frequency voltage.
9. The magneto-electric coupling focused ion transport device of claim 8, wherein the rf frequency applied to the rf multipole (4) is 0.5-5 MHz, the rf peak-to-peak value is 10-500V, and the rf peak-to-peak values on the rod electrodes in any two adjacent rf multipole (4) are equal in amplitude and opposite in phase.
10. Magneto-electric coupling focused ion transport device according to claim 1, characterized in that the working air pressure inside the circular vacuum chamber (2) is maintained in the range of 10Pa to 500 Pa.

Description

Magnetic-electric coupling focusing ion transmission device Technical Field The invention relates to the technical field of mass spectrometry, in particular to a magnetic-electric coupling focusing ion transmission device. Background Mass spectrometers are instruments that perform substance composition and structural analysis by measuring the mass-to-charge ratio (m/z) of ions, and are currently widely used in the fields of biological medicine, environmental monitoring, food safety, and the like. In mass spectrometry, ions are generated in an ionization source and then pass through a transport system before entering a mass analyzer. In this stage of transmission, the ion beam is severely radially diverged due to the influence of various factors such as vacuum expansion, gas collision and charge repulsion, so that a large amount of ions are lost, and the detection sensitivity is severely restricted. In order to improve ion transmission efficiency, the prior art mainly adopts electrostatic lenses, radio frequency multipole rods and other devices. The electrostatic lens focuses ions through an electrostatic field, has a relatively simple structure and low power consumption, but has limited suppression capability for the strong space charge effect generated by a high-density ion beam. Radio frequency multipole rods (e.g., hexapole or octapole rods) are currently the dominant ion guide devices that limit the movement of ions in the radial direction by applying opposite radio frequency voltages to adjacent rod electrodes, thereby creating a dynamic focusing electric field. However, in the face of certain specific application scenarios, such as a first order vacuum region located after an atmospheric pressure ionization source, where the vacuum expansion is extremely intense and the initial ion current density is extremely high. Under this condition, even if a radio frequency multipole is adopted, the initial angular divergence of ions caused by strong expansion and space charge repulsion is still quite remarkable, and the radial constraint by simply relying on an electric field is quite indiscriminate. Accordingly, there is a strong need in the art for a novel device that more effectively suppresses the initial divergence of the ion beam, overcomes the strong space charge effect, and further improves the ion transport efficiency. Disclosure of Invention In view of the shortcomings of the prior art, the invention aims to provide a magneto-electric coupling focusing ion transmission device. The device aims to strongly inhibit radial divergence of the ion beam under the conditions of high pressure difference and high density by the synergistic effect of the axial magnetic field and the radio frequency electric field, and realize efficient transmission of the ion beam in a wide mass range, thereby improving the sensitivity and the ion utilization rate of the mass spectrometer. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention provides a magneto-electric coupling focusing ion transmission device, which comprises a front-end differential electrode, a circular vacuum cavity, a rear-end differential electrode, a radio frequency multipolar rod, a guide magnetic ring and a focusing magnetic ring, wherein the circular vacuum cavity is of a cylindrical structure with two open ends, and the front-end differential electrode and the rear-end differential electrode are of circular flat plate structures with central holes and are respectively connected with the two open ends of the circular vacuum cavity in a sealing insulation manner; the radio frequency multipolar rod comprises at least four rod-shaped electrodes which encircle the outer side of the focusing magnetic ring; The focusing magnetic ring is used for generating a second axial magnetic field, and the magnetic field strength of the second axial magnetic field is larger than that of the first axial magnetic field; the focusing magnetic ring and the radio frequency multipole rod are at least partially overlapped in the axial direction, so that the second axial magnetic field and the radial focusing electric field generated by the radio frequency multipole rod are coupled in a space overlapping manner; And direct-current voltage is applied to each rod-shaped electrode in the front-end differential electrode, the rear-end differential electrode and the radio-frequency multipole rod. The axes of the front-end differential electrode, the rear-end differential electrode, the radio frequency multipole rod, the guide magnetic ring and the focusing magnetic ring are all collinear with the axis of the circular vacuum cavity, and the circle centers of all rod-shaped electrodes in the radio frequency multipole rod are uniformly distributed on the same circumference. The radio frequency multipole rod is a quadrupole rod, a hexapole rod or an octapole rod, wherein the rod-shaped electrodes have the same structure, the le