Bent ion trap, method for controlling a bent ion trap, and mass spectrometer

Abstract

The application relates to the technical field of mass spectrometry instruments, in particular to a curved ion trap, a control method of the curved ion trap and a mass spectrometer. The curved ion trap is formed by designing a quadrupole electrode group in a curved shape, cooperating with a trapping electrode group to form the curved ion trap, applying corresponding voltages to each electrode of the curved ion trap at different time sequences, accurately controlling ions, enabling the ions to be trapped in the curved part of the curved ion trap, and enabling the ions to be pushed out from the radial outlet of the curved ion trap at a specific time sequence. Meanwhile, a lens group is cooperated to improve the pushing-out efficiency of the ion beam. Compared with a linear ion trap design, the curved ion trap provided by the application significantly reduces the overall size, is beneficial to the integration and miniaturization of the ion trap structure, and guarantees the transmission efficiency of the ions.

Description

Technical Field

[0001] This application relates to the field of mass spectrometry analysis instrument technology, and in particular to a curved ion trap, a control method for the curved ion trap, and a mass spectrometer. Background Technology

[0002] As one of the core components of a mass spectrometer, the ion trap is used to capture, store, and analyze the mass of ions. Common ion trap structures include two-dimensional quadrupole ion traps and three-dimensional ion traps. They mainly rely on the radio frequency electric field to form a dynamic potential trap in a specific spatial region to achieve the confinement and stable trapping of ions.

[0003] However, in related technologies, ions in the ion trap can only move along the axial direction of the ion trap, resulting in a long movement path. This leads to low space utilization of the mass spectrometer, limiting its integration and miniaturization. At the same time, during the process of pushing ions from the ion trap to the detector, ions are prone to scattering due to collisions or field distortions, resulting in decreased transmission efficiency and reduced mass resolution, which in turn affects the performance of the mass spectrometer. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art.

[0005] In a first aspect, embodiments of this application provide a curved ion trap, comprising: a curved quadrupole electrode assembly, the quadrupole electrode assembly including a curved first repulsion electrode, a second repulsion electrode, a first side electrode, and a second side electrode, the first and second repulsion electrodes being parallel to each other and arranged opposite to each other, the first and second side electrodes being parallel to each other and arranged opposite to each other, the first and second repulsion electrodes being perpendicular to the first and second side electrodes, and the first and second repulsion electrodes, the first and second repulsion electrodes, the first and second side electrodes being arranged around a central axis of symmetry to form the quadrupole electrode assembly. The curved region inside the quadrupole electrode assembly is used to accommodate trapped ions. The second repulsion electrode is provided with a radial outlet for pushing the trapped ions out of the quadrupole electrode assembly radially. The trapping electrode assembly includes a first end cap electrode and a second end cap electrode. The first end cap electrode is located at one end of the quadrupole electrode assembly, and the second end cap electrode is located at the other end of the quadrupole electrode assembly. The first end cap electrode is provided with an ion inlet for introducing ions into the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly, and the second end cap electrode is provided with an ion outlet for leading ions out of the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly.

[0006] In some embodiments, the curved ion trap further includes a lens group disposed at the radial outlet, comprising a plurality of lenses arranged radially parallel to the quadrupole electrode group, the center of each lens being on the same straight line as the center of the radial outlet.

[0007] In some embodiments, the diameters and voltages of the plurality of lenses decrease sequentially in a direction away from the radial outlet.

[0008] In some embodiments, the curved ion trap further includes a grounding ring, which is directly or indirectly grounded and disposed outside the quadrupole electrode group and the lens group, surrounding the path through which ions are ejected radially from the quadrupole electrode group.

[0009] In some embodiments, the grounding ring is made of a metallic material.

[0010] In some embodiments, during the ion implantation into the quadrupole electrode group and the ion trapping stage of the quadrupole electrode group, the first repulsion electrode and the second repulsion electrode are loaded with a first radio frequency voltage, and the first side electrode and the second side electrode are loaded with a second radio frequency voltage. The first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase.

[0011] In some embodiments, during the ion trapping stage of the quadrupole electrode assembly, a first end cap electrode is loaded with a first DC voltage, and a second end cap electrode is loaded with a second DC voltage. The first DC voltage and the second DC voltage are of the same magnitude, forming a potential trap along the axial direction of the quadrupole electrode assembly for trapping ions in the curved region inside the quadrupole electrode assembly.

[0012] In some embodiments, during the stage where the trapped ions are radially pushed out of the quadrupole electrode group, the first repulsion electrode and the second repulsion electrode are loaded with a third radio frequency voltage, and the first side electrode and the second side electrode are loaded with a fourth radio frequency voltage. The third radio frequency voltage and the fourth radio frequency voltage are equal in magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage.

[0013] In some embodiments, during the stage where the trapped ions are radially pushed out of the quadrupole electrode group, a third DC voltage is applied to the first repulsion electrode and a fourth DC voltage is applied to the second repulsion electrode. The third DC voltage and the fourth DC voltage have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

[0014] In some embodiments, the third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

[0015] Secondly, embodiments of this application provide a control method for a curved ion trap, including the curved ion trap of the first aspect above. The method includes: opening an ion inlet, closing an ion outlet, applying a first DC voltage to a first end cap electrode, applying a first radio frequency voltage to a first repulsion electrode and a second repulsion electrode, applying a second radio frequency voltage to a first side electrode and a second side electrode, and injecting ions into a quadrupole electrode group through the ion inlet according to a first preset time interval; wherein the first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase; closing the ion inlet, applying a second DC voltage to a second end cap electrode, and trapping ions in a curved region inside the quadrupole electrode group according to a second preset time interval. The first DC voltage and the second DC voltage are of the same magnitude. A radial outlet is opened, a third radio frequency voltage is applied to the first and second repulsive electrodes, and a fourth radio frequency voltage is applied to the first and second side electrodes. Simultaneously, the third DC voltage is applied to the first repulsive electrode in a specific timing sequence, and the fourth DC voltage is applied to the second repulsive electrode in a specific timing sequence. The trapped ions are then radially ejected from the quadrupole electrode group according to a third preset time interval. The third and fourth radio frequency voltages are of equal magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage. The third and fourth DC voltages have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

[0016] In some embodiments, the third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

[0017] In some embodiments, while opening the radial outlet, the method further includes: reducing a first DC voltage applied to the first end cap electrode and a second DC voltage applied to the second end cap electrode.

[0018] In some embodiments, the third and fourth DC voltages have the same polarity as the trapped ions.

[0019] In some embodiments, the method further includes: injecting a gaseous medium into the quadrupole electrode assembly to increase the pressure inside the quadrupole electrode assembly and reduce the kinetic energy of the ions through the gaseous medium.

[0020] In some embodiments, the gaseous medium is nitrogen.

[0021] Thirdly, embodiments of this application provide a mass spectrometer including the curved ion trap described in the first aspect embodiment above.

[0022] The technical solution provided in this application, by designing a curved quadrupole electrode assembly in conjunction with a trapping electrode assembly to form a curved ion trap, applies corresponding voltages to each electrode of the curved ion trap structure at different times, thereby achieving precise control of ions. This allows ions to be trapped in the curved part of the curved ion trap and ejected from the radial outlet of the curved ion trap at specific times. Compared with the straight ion trap design, the curved ion trap provided in this application significantly reduces the overall size, which is beneficial for the integration and miniaturization of the ion trap structure. At the same time, the lens assembly provided in this application can further improve the ion beam ejection efficiency, thereby improving the detection sensitivity of the mass spectrometer.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of the structure of the bent ion trap provided in the embodiments of this application;

[0026] Figure 2 This is a schematic cross-sectional view of a curved ion trap provided in an embodiment of this application;

[0027] Figure 3 This is a schematic diagram illustrating the relationship between voltage and time stages on the capture electrode assembly provided in an embodiment of this application;

[0028] Figure 4 A flowchart illustrating the control method for a bent ion trap provided in this application embodiment;

[0029] Figure 5 A schematic diagram of the ion movement trajectory within the ion trap during the ion implantation stage, provided in an embodiment of this application.

[0030] Figure 6 A schematic diagram of the ion trajectory within the ion trap during the ion trapping stage provided in this application embodiment;

[0031] Figure 7 This is a schematic diagram of the trajectory of ions within the ion trap during the ejection stage, provided as an embodiment of this application.

[0032] Reference numerals: 11-First repulsion electrode; 12-Second repulsion electrode; 13-First side electrode; 14-Second side electrode; 121-Radial outlet; 21-First end cap electrode; 22-Second end cap electrode; 30-Lens group; 40-Grounding ring; 50-Detector. Detailed Implementation

[0033] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0034] It should be understood that the steps described in the method embodiments of this application may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this application is not limited in this respect.

[0035] As described in the background section, in related technologies, ions move along the axial direction of the ion trap, which results in a long ion movement path and thus low spatial layout efficiency of the instrument, limiting the development of miniaturization and integration. Secondly, when ions are pushed from the ion trap to the detector (such as a mass analyzer), ions are easily scattered in the ion trap due to collisions or field distortion, which leads to a decrease in ion transmission rate and mass resolution. In addition, it is difficult for the ion trap to focus ions during the extrapolation phase, making it difficult to achieve efficient ion beam convergence and wires, thereby further limiting the overall sensitivity and resolution performance of the instrument.

[0036] To address the aforementioned problems, this application proposes a curved ion trap, and embodiments of the curved ion trap of this application are described below with reference to the accompanying drawings.

[0037] refer to Figure 1 and Figure 2The curved ion trap provided in this application includes a curved quadrupole electrode assembly and a trapping electrode assembly. The quadrupole electrode assembly includes a curved first repulsion electrode 11, a second repulsion electrode 12, a first side electrode 13, and a second side electrode 14. The first repulsion electrode 11 and the second repulsion electrode 12 are parallel and opposite to each other, as are the first side electrode 13 and the second side electrode 14. The first repulsion electrode 11 and the second repulsion electrode 12 are perpendicular to the first side electrode and the second side electrode 14. The four electrodes of the quadrupole electrode assembly form a trap-like channel. When a voltage is applied to the quadrupole electrode assembly, ions can pass through the channel. In the motion, the curved regions of the first repulsion electrode 11 and the second repulsion electrode 12, together with the first side electrode 13 and the second side electrode 14, form a curved region. The curved region is used to accommodate ions trapped in the ion trap. The curved region of the second repulsion electrode 12 is provided with a radial outlet 121. By applying a voltage to the first repulsion electrode 11 and the second repulsion electrode 12 to form an electric field, the ions trapped in the curved region of the ion trap can be pushed out of the four-stage motor unit through the radial outlet 121 of the second repulsion electrode 12.

[0038] The trapping electrode assembly includes a first cap electrode 21 and a second cap electrode 22, which are respectively disposed at both ends of the quadrupole electrode assembly. The first cap electrode 21 has an inlet, and by applying voltage to the first cap electrode 21, ions can be introduced into the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly. The second cap electrode 22 has an outlet, and by applying voltage to the second cap electrode 22, ions can be led out of the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly. At the same time, by applying voltage to both the first cap electrode 21 and the second cap electrode 22, in conjunction with the quadrupole electrode assembly, ions can be trapped within the quadrupole electrode assembly.

[0039] As an optional embodiment, the curved ion trap further includes a lens group 30 disposed at the radial outlet 121, comprising a plurality of lenses arranged radially parallel to the quadrupole electrode group, the center of each lens being on the same straight line as the center of the radial outlet 121.

[0040] Specifically, the curved ion trap also includes a lens group 30, which includes a plurality of lenses arranged parallel to the first repulsion electrode 11. The lens group 30 is coaxially arranged with the radial outlet 121 of the second repulsion electrode 12 of the quadrupole electrode group, so that after the ions are emitted from the radial outlet 121, they can be constrained by the lens group 30 and emitted along the central axis of the lens group 30 to the downstream detector 50, thereby significantly reducing ion scattering loss.

[0041] As an alternative embodiment, the diameters of the multiple lenses and the voltage decrease sequentially in a direction away from the radial outlet 121.

[0042] Specifically, the lenses used in the curved ion trap provided in this application embodiment are preferably electrostatic lenses. Each lens in the lens group 30 has a through-hole at its center, allowing ions to exit along the through-hole path of the lens group 30. The diameters of the through-holes in the multiple lenses in the lens group 30 decrease sequentially along the direction away from the radial outlet 121 of the quadrupole electrode group. For example, when the lens group 30 has four lenses, a DC voltage of 150V is applied to the first lens closest to the radial outlet 121, a DC voltage of 100V is applied to the second lens, a DC voltage of 50V is applied to the third lens, and a voltage of 0V is applied to the fourth lens. This sequentially decreasing arrangement allows the lenses to progressively constrain the spatial distribution of ions, ensuring that more ions can enter the next stage lens, effectively reducing the risk of ion depletion. Ions are lost due to scattering during flight; applying a voltage to the lens group 30 can create an electric field, allowing ions to move along the through-hole of the lens under the influence of the electric field force. The voltage on multiple lens groups 30 decreases sequentially along the radial outlet 121 away from the quadrupole electrode group, which can achieve the formation of a gradient non-uniform electric field, so that the speed of ions flying along the through-hole gradually decreases and is finally focused at the entrance of the detector 50, thereby reducing energy dispersion. At the same time, the gradient voltage design can also disperse the ion beam density, reduce Coulomb repulsion between multiple lenses, and prevent high-energy ions from deviating from the through-hole due to aggregation effect. In addition, the low voltage and small aperture of the last stage of the lens group 30 can effectively compress the ion beam diameter, increase the ion flux entering the detector 50, and enhance the detection sensitivity.

[0043] It should be noted that the voltage gradient of multiple lenses in lens group 30 can be dynamically adjusted according to ions with different mass-to-charge ratios to adapt to the focusing requirements of different low-mass or high-mass ions, thus making the mass spectrometer more applicable.

[0044] As an optional embodiment, the curved ion trap further includes a grounding ring 40, which is directly or indirectly grounded and disposed outside the quadrupole electrode group and the lens group 30, surrounding the path through which ions are ejected radially from the quadrupole electrode group.

[0045] As an optional embodiment, the grounding ring 40 is made of a metallic material.

[0046] Specifically, the grounding ring 40 is disposed outside the quadrupole electrode group and the lens group 30, and surrounds the path through which ions are radially ejected from the quadrupole electrode group. The grounding ring 40 is made of conductive metal materials, including but not limited to stainless steel, and is directly connected to ground or indirectly connected to ground through a specific circuit. When the grounding ring 40 is energized, the free electrons on its surface will redistribute due to the electric field, thereby forming an induced electric field opposite to the external electric field, thus canceling the electric field distortion at the edge of the motor and ensuring that the potential in the area near the grounding ring 40 remains stable.

[0047] The grounding ring 40 can also introduce a smooth potential distribution when there is a high potential gradient at the edge of the quadrupole electrode group, thereby preventing ions from deviating from the preset flight trajectory due to sudden changes in the electric field during transmission. At the same time, the grounding ring 40 can also provide a low-impedance path for the parasitic field of high-frequency oscillation at the edge of the quadrupole electrode group, and guide such high-frequency noise to the ground terminal to reduce interference to the ion beam. In addition, the grounding ring 40 can also release the space charge accumulated in the ion beam to maintain local electrical neutrality, further preventing the occurrence of electric field distortion caused by charge accumulation.

[0048] As an optional embodiment, during the ion implantation into the quadrupole electrode group and the ion trapping stage of the quadrupole electrode group, the first repulsion electrode 11 and the second repulsion electrode 12 are loaded with a first radio frequency voltage, and the first side electrode 13 and the second side electrode 14 are loaded with a second radio frequency voltage. The first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase.

[0049] Specifically, applying a first radio frequency voltage to the first repulsion electrode 11 and the second repulsion electrode 12 generates a first alternating electric field in the radial direction of the quadrupole electrode group. Applying a second radio frequency voltage to the first side electrode 13 and the second side electrode 14 generates a second alternating electric field in the axial direction of the quadrupole electrode group. The magnitudes of the first and second radio frequency voltages are approximately equal to ensure that the first and second alternating electric fields are symmetrical in both the axial and radial directions, thus stably confining the ions in the quadrupole electrode group. At the same time, the phase difference between the first and second radio frequency voltages is 180°, causing a rotating hyperbolic potential field to be formed in the central region (bent region) of the quadrupole electrode group. After entering this region, the ions are subjected to a rapidly alternating force pointing towards the center, so that the ions can be stably confined near the central region.

[0050] refer to Figure 3 This is a schematic diagram showing the relationship between the voltage and time stages of the capture electrode group provided in the embodiments of this application.

[0051] As an optional embodiment, during the ion trapping stage of the quadrupole electrode group, a first DC voltage is applied to the first end cap electrode 21 and a second DC voltage is applied to the second end cap electrode 22. The first DC voltage and the second DC voltage are of the same magnitude, forming a potential trap along the axial direction of the quadrupole electrode group, which is used to trap ions in the curved region inside the quadrupole electrode group.

[0052] Specifically, during the ion implantation stage of the quadrupole electrode group, a first DC voltage is applied to the first end cap electrode 21, while no voltage is applied to the second end cap electrode 22. At this time, ions can be injected into the quadrupole electrode group under the action of the electric field formed by the first end cap electrode 21. After the implantation is completed, the voltage applied to the first end cap electrode 21 and the second end cap electrode 22 remains unchanged until the next stage is entered.

[0053] During the ion trapping stage of the quadrupole electrode group, a first DC voltage is applied to the first end cap electrode 21, and a second DC voltage is applied to the second end cap electrode 22. The magnitude and phase of the first DC voltage and the second DC voltage are consistent to form a symmetrical and stable electrostatic potential trap in the axial direction. This allows ions to be successfully trapped in the curved region inside the quadrupole electrode group, laying the foundation for efficient ion ejection from the radial outlet 121 of the quadrupole electrode group and reducing ion loss.

[0054] As an optional embodiment, during the stage where the trapped ions are radially pushed out of the quadrupole electrode group, the first repulsion electrode 11 and the second repulsion electrode 12 are loaded with a third radio frequency voltage, and the first side electrode 13 and the second side electrode 14 are loaded with a fourth radio frequency voltage. The third radio frequency voltage and the fourth radio frequency voltage are equal in magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage.

[0055] As an optional embodiment, during the stage where the trapped ions are radially pushed out of the quadrupole electrode group, the first repulsion electrode 11 is loaded with a third DC voltage and the second repulsion electrode 12 is loaded with a fourth DC voltage. The third DC voltage and the fourth DC voltage have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

[0056] As an optional embodiment, the third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

[0057] Specifically, during the stage where the trapped ions are radially pushed out of the quadrupole electrode group, a third radio frequency voltage is applied to the first repulsion electrode 11 and the second repulsion electrode 12, and a fourth radio frequency voltage is applied to the first side electrode 13 and the second side electrode. The third radio frequency voltage is less than the first radio frequency voltage. For example, if the first radio frequency voltage is 500V, the third radio frequency voltage can be 480V to retain the radio frequency electric field. At the same time, during this stage, a third DC voltage is applied to the first repulsion electrode 11 and a fourth DC voltage is applied to the second repulsion electrode 12 to form a repulsion electric field.

[0058] The retention of the radio frequency (RF) electric field stabilizes the ion distribution within the quadrupole electrode assembly, ensuring that ions flying in other directions can be recaptured, thus improving ion transport efficiency. Simultaneously, under certain conditions, the first side electrode 13 and the second side electrode 14 can also be applied with a DC voltage to further achieve a repulsive electric field that better matches the RF electric field. Preferably, the applied DC voltage is greater than 150V. Furthermore, the retention of the RF electric field can counteract ion diffusion caused by the repulsive electric field, preventing energetic ions from deviating from the ejection orifice path due to excessive acceleration. The RF electric field also maintains a uniform ion distribution within the quadrupole electrode assembly, thereby reducing signal distortion caused by Coulomb forces during ion ejection.

[0059] It should be noted that by adjusting the ratios of the third and fourth DC voltages to the third and fourth RF voltages, the timing and efficiency of ion ejection from radial outlet 121 can be controlled, thereby avoiding abrupt changes in ion trajectory caused by the removal of the RF voltage. Furthermore, retaining the RF electric field can prevent repeated application of the RF electric field, shortening the instrument's scanning cycle.

[0060] In some related technologies, the radio frequency (RF) voltage needs to be cut off during ion ejection, and repulsion voltages need to be applied to the other three electrodes of the quadrupole electrode group besides the ejection electrode. However, in this application, the RF voltage is still kept at a relatively high value, which can still maintain the trapping and restriction of ions. Ion ejection can be achieved by applying repulsion voltage to only one pair of repulsion electrodes, which helps to simplify control parameters and improve control effect. By reducing the reduction of the RF voltage of the quadrupole electrode group, a larger RF voltage is maintained during ion ejection. This allows the repulsion electric field and the RF electric field to superimpose and form an asymmetric trap. Ions can preferentially escape along the radial exit 121. During the process of ion repulsion, the RF electric field can continue to screen the ion mass, so that ions with a specific mass-to-charge ratio can overcome the electric field force of the RF electric field and be ejected from the radial exit 121. At the same time, it prevents the ions from being excessively accelerated by the repulsion electric field, which would cause the ion flight path to deviate. This achieves precise control of ion release and ensures the accuracy of the detector 50.

[0061] It should be noted that in related technologies, during ion ejection, the radio frequency voltage is preferably reduced to 0.3-0.7 times the original radio frequency voltage. Taking the first radio frequency voltage of 500V in this application as an example, it needs to be reduced to 150V-350V. However, this application only reduces it by 20V, which is less than 10%. Correspondingly, the third radio frequency voltage provided in this application embodiment needs to be less than the first radio frequency voltage and greater than 75% of the first radio frequency voltage. A larger radio frequency voltage can ensure that the released ions are better confined in the central region of the quadrupole electrode group. In order to avoid pushing the ions towards the first repulsion electrode 11 and the second repulsion electrode 12 due to excessive electric field force during ion ejection, this application also applies a third DC voltage and a fourth DC voltage of the same polarity to the first repulsion electrode 11 and the second repulsion electrode 12, so that the ions can be ejected while the radio frequency voltage is kept at a high voltage.

[0062] According to the curved ion trap provided in the embodiments of this application, by designing a curved quadrupole electrode group in conjunction with a trapping electrode group to form a curved ion trap, corresponding voltages are applied to each electrode of the curved ion trap structure at different times to achieve precise control of ions. This allows ions to be trapped in the curved part of the curved ion trap and to be ejected from the radial outlet of the curved ion trap at specific times. At the same time, a lens group is used to improve the ion beam ejection efficiency. Compared with the straight ion trap design, the curved ion trap provided in this application significantly reduces the overall size, which is beneficial for the integration and miniaturization of the ion trap structure, and ensures the ion transmission efficiency.

[0063] Based on the same concept, this application also provides a control method for a curved ion trap, which is applied to the curved ion trap described above.

[0064] refer to Figure 4 This is a flowchart of a control method for a curved ion trap provided in an embodiment of this application.

[0065] Step S401: Open the ion inlet, close the ion outlet, apply a first DC voltage to the first end cap electrode 21, apply a first radio frequency voltage to the first repulsion electrode 11 and the second repulsion electrode 12, apply a second radio frequency voltage to the first side electrode 13 and the second side electrode 14, and inject ions into the quadrupole electrode group through the ion inlet according to a first preset time interval; wherein, the first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase.

[0066] Specifically, such as Figure 5As shown, when the curved ion trap starts working, the ion inlet of the curved ion trap is first opened and the ion outlet is closed. A first DC voltage is applied to the first end cap electrode 21, a first radio frequency voltage is applied to the first repulsion electrode 11 and the second repulsion electrode 12, and a second radio frequency voltage is applied to the first side electrode 13 and the second side electrode 14, so that ions can be injected into the quadrupole electrode group from the ion inlet according to a first preset time interval. The curved ion trap then captures the ions. The first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase, so that the electric field in the ion trap can stably bind the ions in the curved region. In the embodiments of this application, the first preset time interval is preferably 25 μs, the first DC voltage is preferably 100 V, and the first radio frequency voltage is preferably 500 V.

[0067] Step S402: Close the ion inlet, apply a second DC voltage to the second end cap electrode 22, and trap the ions in the curved region inside the quadrupole electrode group according to the second preset time interval; wherein the magnitudes of the first DC voltage and the second DC voltage are the same.

[0068] Specifically, after ion implantation is complete, the ion outlet is shut off, and a second DC voltage is applied to the second end cap. The currents of the first and second DC voltages are equal, causing the curved ion trap to form a stable and symmetrical electrostatic potential trap in the axial direction. At this time, the radio frequency voltages applied to the first repulsion electrode 11, the second repulsion electrode 12, the first side electrode 13, and the second side electrode 14 remain unchanged, so that ions can be trapped in the curved region inside the quadrupole electrode assembly within a second preset time interval. Figure 6 As shown. In this embodiment of the application, the second preset time interval is preferably 45µs.

[0069] Step S403: Open the radial outlet 121, apply a third radio frequency voltage to the first repulsion electrode 11 and the second repulsion electrode 12, apply a fourth radio frequency voltage to the first side electrode 13 and the second side electrode 14, and simultaneously apply a third DC voltage to the first repulsion electrode 11 in a specific timing sequence, apply a fourth DC voltage to the second repulsion electrode 12 in a specific timing sequence, and push the trapped ions out of the quadrupole electrode group radially along the quadrupole electrode group according to a third preset time interval; wherein, the third radio frequency voltage and the fourth radio frequency voltage are equal in magnitude and 180° out of phase, the third radio frequency voltage is less than the first radio frequency voltage, the third DC voltage and the fourth DC voltage have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

[0070] As an optional embodiment, the third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

[0071] Specifically, after the ions have been stably trapped inside the curved ion trap, the radial outlet 121 is opened, and a third radio frequency voltage is applied to the first repulsion electrode 11 and the second repulsion electrode 12, and a fourth radio frequency voltage is applied to the first side electrode 13 and the second side electrode 14. The third and fourth radio frequency voltages are equal in magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage but also greater than 75% of the first radio frequency voltage to maximize the retention of the radio frequency electric field within the ion trap. This allows the ions to be stably distributed in the central part (curved part) of the ion trap, reducing ion escape and improving ion transport efficiency. Simultaneously, the first repulsion electrode 11... A third DC voltage is applied to the first repulsion electrode 11 and the second repulsion electrode 12 according to a specific timing sequence. The third and fourth DC voltages have the same polarity, which effectively prevents ions from escaping and colliding with the first and second repulsion electrodes 11 and 12. Furthermore, the trapped ions are ejected from the quadrupole electrode group through the radial outlet 121 according to a third preset time interval. In this embodiment, the third preset time interval is preferably 10 μs, and the third DC voltage needs to be greater than the fourth DC voltage so that the ions can detach from the quadrupole electrode group through the radial outlet 121 under the action of the electric field force, and after being focused by the lens group 30, reach the detector 50 for mass analysis. Figure 7 As shown.

[0072] As an optional embodiment, while opening the radial outlet 121, the method further includes: reducing a first DC voltage applied to the first end cap electrode 21 and a second DC voltage applied to the second end cap electrode 22.

[0073] Specifically, while opening the radial outlet 121, it is necessary to reduce the DC voltage on the first end cap electrode 21 and the second end cap electrode 22. For example, when the first DC voltage is 100V, the fifth DC voltage and the sixth DC voltage are 20V. By reducing the DC voltage on the first end cap electrode 21 and the second end cap electrode 22, the axial constraint force of ions in the ion trap is weakened, making it easier for ions to be ejected from the radial outlet 121 under the action of the repulsive electric field. This effectively avoids the decrease in ejection efficiency caused by excessive axial constraint force, and improves the transmission efficiency of ions entering the detector 50. At the same time, reducing the DC voltage on the first end cap electrode 21 and the second end cap electrode 22 can reduce the distribution area of ​​ions in the ion trap, reduce the repulsive effect of Coulomb force between ions, and make the ion beam more concentrated during ejection, thereby reducing signal distortion.

[0074] It should be noted that the reduced first DC voltage and second DC voltage can be set according to the third RF voltage and fourth RF voltage, thereby realizing the controllable release of ions in a preset time sequence, which can be applied to tandem mass spectrometry scenarios that require rapid switching of detector 50 analysis modes.

[0075] As an optional embodiment, the third and fourth DC voltages have the same polarity as the trapped ions.

[0076] Specifically, according to Coulomb's law, like charges hold each other, and the third and fourth DC voltages need to be of the same polarity as the trapped ions so that the ions can generate a repulsive force to push the ions away from the quadrupole electrode group. If a voltage of opposite polarity is applied, an electric field of opposite polarity will be generated, which will attract the ions and cause them to collide with the repulsive electrodes, eventually neutralizing and annihilating on the electrode surface. The ions will then be unable to enter the detector 50, resulting in signal loss.

[0077] As an optional embodiment, the method further includes: injecting a gaseous medium into the quadrupole electrode assembly to increase the pressure inside the quadrupole electrode assembly and reduce the ion kinetic energy through the gaseous medium.

[0078] As an optional embodiment, the gas medium is nitrogen.

[0079] Specifically, during the ion implantation and trapping stages, a gas at a certain pressure needs to be injected into the quadrupole electrode assembly. The ions entering the quadrupole electrode assembly will lose kinetic energy through collisions with the gas, so that the ions can be better concentrated in the curved region. In the embodiments of this application, the gas at a certain pressure is preferably nitrogen. Nitrogen is an inert gas, which can avoid unnecessary side reactions with ions and has the advantages of low acquisition cost and high energy transfer efficiency when colliding with ions.

[0080] The control method for the curved ion trap described above has the same beneficial effects as the curved ion trap, which will not be elaborated further here.

[0081] Based on the same concept, this application also provides a mass spectrometer, including the aforementioned curved ion trap. The mass spectrometer provided by this application can effectively improve the space utilization of the ion trap through the aforementioned curved ion trap, and improve the ion ejection efficiency and focusing ability, thereby significantly enhancing the mass analysis performance of the mass spectrometer, enabling the mass spectrometer to be applied to high-sensitivity or high-resolution mass spectrometry analysis scenarios.

[0082] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0083] From the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of computer software products plus necessary general-purpose hardware platforms, and of course, they can also be implemented by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.) and includes several instructions to cause the terminal or network-side device to execute the methods described in the various embodiments of this application.

[0084] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other implementations under the guidance of this application without departing from the spirit and scope of the claims. All of these implementations are within the protection scope of this application.

Claims

1. A curved ion trap, characterized in that, include: A curved quadrupole electrode assembly includes a curved first repulsion electrode (11), a second repulsion electrode (12), a first side electrode (13), and a second side electrode (14). The first repulsion electrode (11) and the second repulsion electrode (12) are parallel to each other and arranged opposite to each other. The first side electrode (13) and the second side electrode (14) are parallel to each other and arranged opposite to each other. The first repulsion electrode (11) and the second repulsion electrode (12) are perpendicular to the first side electrode (13) and the second side electrode (14). The first repulsion electrode (11), the second repulsion electrode (12), the first side electrode (13), and the second side electrode (14) surround a central axis of symmetry to form the quadrupole electrode assembly. The curved region inside the quadrupole electrode assembly is used to accommodate trapped ions. The second repulsion electrode (12) is provided with a radial outlet (121) for pushing the trapped ions out of the quadrupole electrode assembly radially. The capture electrode assembly includes a first end cap electrode (21) and a second end cap electrode (22). The first end cap electrode (21) is disposed at one end of the quadrupole electrode assembly, and the second end cap electrode (22) is disposed at the other end of the quadrupole electrode assembly. The first end cap electrode (21) is provided with an ion inlet for introducing ions into the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly, and the second end cap electrode (22) is provided with an ion outlet for leading ions out of the quadrupole electrode assembly along the axial direction of the quadrupole electrode assembly.

2. The curved ion trap according to claim 1, characterized in that, Also includes: The lens group (30) is disposed at the radial outlet (121) and includes a plurality of lenses arranged radially parallel to the quadrupole electrode group, the center of each lens being on the same straight line as the center of the radial outlet (121).

3. The curved ion trap according to claim 2, characterized in that, The diameters and voltages of the plurality of lenses decrease sequentially in a direction away from the radial outlet (121).

4. The curved ion trap according to claim 2, characterized in that, Also includes: A grounding ring (40) is directly or indirectly grounded and is disposed outside the quadrupole electrode group and the lens group (30), surrounding the path through which ions are pushed out radially along the quadrupole electrode group.

5. The curved ion trap according to claim 4, characterized in that, The grounding ring (40) is made of metal.

6. The curved ion trap according to claim 1, characterized in that, During the ion implantation into the quadrupole electrode group and the ion trapping stage of the quadrupole electrode group, the first repulsion electrode (11) and the second repulsion electrode (12) are loaded with a first radio frequency voltage, and the first side electrode (13) and the second side electrode (14) are loaded with a second radio frequency voltage. The first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase.

7. The curved ion trap according to claim 6, characterized in that, During the ion trapping stage of the quadrupole electrode group, the first end cap electrode (21) is loaded with a first DC voltage, and the second end cap electrode (22) is loaded with a second DC voltage. The first DC voltage and the second DC voltage are of the same magnitude, forming a potential trap along the axial direction of the quadrupole electrode group, which is used to trap ions in the curved region inside the quadrupole electrode group.

8. The curved ion trap according to claim 6, characterized in that, During the stage where the trapped ions are pushed out of the quadrupole electrode group radially, the first repulsion electrode (11) and the second repulsion electrode (12) are loaded with a third radio frequency voltage, and the first side electrode (13) and the second side electrode (14) are loaded with a fourth radio frequency voltage. The third radio frequency voltage and the fourth radio frequency voltage are equal in magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage.

9. The curved ion trap according to claim 8, characterized in that, During the stage where the trapped ions are pushed out of the quadrupole electrode group radially, the first repulsion electrode (11) is loaded with a third DC voltage and the second repulsion electrode (12) is loaded with a fourth DC voltage. The third DC voltage and the fourth DC voltage have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

10. The curved ion trap according to claim 9, characterized in that, The third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

11. A method for controlling a bent ion trap, characterized in that, Applied to the bent ion trap as described in any one of claims 1-10, the method comprises: The ion inlet is opened and the ion outlet is closed. A first DC voltage is applied to the first end cap electrode, a first radio frequency voltage is applied to the first and second repulsion electrodes, and a second radio frequency voltage is applied to the first and second side electrodes. Ions are injected into the quadrupole electrode group through the ion inlet according to a first preset time interval. The first radio frequency voltage and the second radio frequency voltage are equal in magnitude and 180° out of phase. The ion inlet is closed, a second DC voltage is applied to the second end cap electrode, and ions are trapped in the curved region inside the quadrupole electrode group according to a second preset time interval; wherein the first DC voltage and the second DC voltage are of the same magnitude. A radial outlet is opened, a third radio frequency voltage is applied to the first and second repulsion electrodes, a fourth radio frequency voltage is applied to the first and second side electrodes, a third DC voltage is applied to the first repulsion electrode in a specific timing sequence, and a fourth DC voltage is applied to the second repulsion electrode in a specific timing sequence. The trapped ions are then ejected radially from the quadrupole electrode group according to a third preset time interval. The third radio frequency voltage and the fourth radio frequency voltage are equal in magnitude and 180° out of phase. The third radio frequency voltage is less than the first radio frequency voltage. The third DC voltage and the fourth DC voltage have the same polarity, and the third DC voltage is greater than the fourth DC voltage.

12. The control method for the curved ion trap according to claim 11, characterized in that, The third radio frequency voltage is greater than or equal to 75% of the first radio frequency voltage.

13. The control method for the curved ion trap according to claim 11, characterized in that, While opening the radial outlet, the method further includes: Reduce the first DC voltage applied to the first end cap electrode and the second DC voltage applied to the second end cap electrode.

14. The control method for the curved ion trap according to claim 11, characterized in that, The third DC voltage and the fourth DC voltage have the same polarity as the trapped ions.

15. The control method for a curved ion trap according to claim 11, characterized in that, The method further includes: A gaseous medium is injected into the quadrupole electrode assembly to increase the pressure inside the quadrupole electrode assembly and reduce the kinetic energy of the ions through the gaseous medium.

16. The control method for a curved ion trap according to claim 15, characterized in that, The gaseous medium is nitrogen.

17. A mass spectrometer, characterized in that, Including the curved ion trap as described in any one of claims 1-10.

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