Ion cyclotron resonance device, control method, and mass spectrometer

Abstract

The application provides an ion cyclotron resonance device for mass spectrometry, a control method and a mass spectrometer. The device comprises a cylindrical space region for ion introduction, excitation and detection. In the ion excitation process, the ions are excited radially outward from the center of the cylindrical space region. A pair of magnets are arranged axially parallel to the cylindrical space region for generating a magnetic field in the space region. The magnets have opposite polarities. The opposite surfaces of the magnets are perpendicular to the axial direction. The magnetic field intensity of the central region of the space region is greater than that of the outer peripheral region along the radial direction. An electrode array is arranged between the pair of magnets. An alternating voltage is applied to the electrodes of the electrode array for exciting the ions. The ion cyclotron resonance device can solve multiple problems such as device miniaturization, resolution, equipment and manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of analytical technology, specifically to an ion cyclotron resonance device, a control method for the ion cyclotron resonance device, and a mass spectrometer having an ion cyclotron resonance device. Background Technology

[0002] Among currently commercially available mass spectrometry techniques, Fourier transform ion cyclotron resonance (FT-ICR) offers the highest achievable mass resolution. Consequently, due to the high resolution of ion cyclotron resonance devices, it is primarily used in testing scenarios requiring high mass resolution.

[0003] Magnetic field strength and uniformity are generally considered important parameters of ion cyclotron resonance (ICR) devices, directly affecting their resolution as mass analyzers. To achieve high resolution, a high vacuum environment (typically 10⁻⁶) is required for the ICR device. -7 Ion cyclotron resonance (ICR) devices operate in high vacuum environments on the order of Pa and in high-intensity magnetic fields (up to 10T or more). However, to achieve these high vacuum environments and high-intensity magnetic fields, the vacuum pump systems and superconducting magnet systems required for ICR devices are enormous and expensive. This undoubtedly limits the application of ICR technology in relatively compact or small mass spectrometers.

[0004] On the other hand, due to the inherent characteristics of ion cyclotron resonance devices, reducing the requirements for vacuum level, magnetic field strength, and uniformity will drastically decrease the resolution of the device, rendering it unsuitable for routine testing. For example, even a slight decrease in vacuum level (e.g., to 10) would significantly reduce its resolution. -4 (On the order of Pa) Because improving resolution requires maintaining the continuous periodic rotation of excited ions, a decrease in vacuum means that gas is introduced into the ion cyclotron resonance device. Even a small amount of gas molecules can easily collide with ions during the long-term continuous rotation of ions, causing the ions to dephasing rapidly and resulting in a sharp decrease in resolution.

[0005] Furthermore, the magnetic field of an ion cyclotron resonance device can only bind ions in the radial direction of ion cyclotron, but not in the axial direction. Currently, the common method for applying axial binding force to ions is to apply a DC electrostatic field to the two end caps of the ion cyclotron resonance device. This axial DC electrostatic field not only causes periodic ion movement in the axial direction but also generates so-called "magnetron motion" on the cyclotron resonance plane. Magnetron motion is a low-frequency precession that affects the frequency of the cyclotron resonance, and this effect is non-uniform in the axial direction, potentially leading to a decrease in resolution and quality accuracy. Additionally, the axial binding electric field also affects the radial excitation electric field. Specifically, for a cubic ion trap, applying a DC electrostatic field to the two end caps inevitably distorts the original excitation electric field. The uniformity of the excitation electric field also affects the final resolution. Several structures have been developed to address these issues. For example, multiple specially curved electrodes are used to form a so-called "harmony cell," decoupling axial and radial motion to reduce the influence of the axial confinement field (Eugene N. Nikolaev, J. Am. Soc. Mass Spectrom. (2011) 22: 1125-1133); or a so-called "infinity trap" technique using discrete excitation electrodes is employed to obtain a uniform excitation field (P. Caravatti, M. Allemann, Org. Mass Spectrom. 26, 1991, 514–518). However, these structures inevitably require complex and precise electrode designs, making manufacturing difficult.

[0006] In summary, there is a need for an ion cyclotron resonance device or mass spectrometer that can address multiple issues, including miniaturization, resolution, and equipment and manufacturing costs. For example, a mass spectrometer that uses an ion cyclotron resonance device as a mass analyzer could be provided, miniaturizing the mass spectrometer to a benchtop size or a portable size while ensuring that the resolution meets the requirements of daily testing. Summary of the Invention

[0007] To address the above problems, this invention provides an ion cyclotron resonance device, a control method for the ion cyclotron resonance device, and a mass spectrometer with an ion cyclotron resonance device, which can simultaneously solve multiple problems including equipment miniaturization, resolution, and equipment and manufacturing costs.

[0008] This invention provides an ion cyclotron resonance device for mass spectrometry analysis, comprising a cylindrical spatial region for ion introduction, excitation, and detection. During ion excitation, ions are excited radially outward from the center of the cylindrical spatial region; a pair of magnets are arranged parallel to the axial direction of the cylindrical spatial region to generate a magnetic field within the region, with their opposing surfaces perpendicular to the axial direction, and the magnetic field strength in the central region of the spatial region being greater than that in the radially peripheral region; an electrode array is disposed between the pair of magnets, and an alternating voltage is applied to the electrodes of the electrode array to excite ions.

[0009] According to the technical solution provided by the present invention, because the magnetic field strength in the central region of the spatial region is greater than that in the outer region, the magnetic field distribution of strong at the center and weak around the periphery will cause the ions to be bound by a force along the axial direction. In this way, the ion cyclotron resonance device provided by the present invention can eliminate the need for the DC electrostatic field used in the prior art to generate the axial binding force, avoiding the distortion of the excitation electric field and the change in the ion cyclotron frequency caused by applying an additional electric field.

[0010] In addition, the present invention confines ions within a planar region, and the electrode array for the excitation electric field can be arranged in parallel, which can generate a very uniform excitation electric field along the excitation direction, thus improving the resolution of the device.

[0011] Because there is no distortion of the excitation electric field and no broadening of the resonant frequency due to the axial electric field, the instrument's resolution can still meet the needs of daily testing even if the detection time, equipment vacuum level, and magnetic field strength are reduced. For example, simulation results show that by applying some of the technical solutions of this invention, the ion cyclotron resonance device can achieve a resolution of 10... -4 It operates normally under a vacuum of Pa, and under a magnetic field of 1T, a detection time of 50ms can achieve a resolution of 4k. Mass spectrometers operating under these magnetic field and vacuum conditions have the potential for miniaturization to benchtop or portable sizes.

[0012] Preferably, in the optional technical solution of the present invention, the magnet is a permanent magnet.

[0013] Using permanent magnets as the magnetic field provider has several advantages. First, for widely used cylindrical and disk-shaped permanent magnets that are uniformly magnetized along the axial direction, the field strength in the central region of their two end faces is usually stronger than that in the outer region. Simply placing the end faces of two permanent magnets of roughly the same shape and size facing each other can create a magnetic pole plane that meets the magnetic field strength distribution requirements, making pole fabrication very simple. Second, using permanent magnets to generate a rotating magnetic field for ions eliminates the need for external equipment such as a power supply, effectively reducing equipment and maintenance costs.

[0014] Preferably, in an optional embodiment of the present invention, the electrode array comprises two sets of electrode arrays arranged parallel to the circular surface of the cylindrical spatial region, each set of electrode arrays comprising multiple parallel and equally spaced wire electrodes. Using multiple parallel and equally spaced wire electrodes can generate a uniform excitation electric field, and these regular wire electrodes are also easy to manufacture, further reducing manufacturing costs.

[0015] Preferably, in an optional technical solution of the present invention, at least two detection electrodes disposed between a pair of magnets are further included for detecting the mirror current of ions.

[0016] Preferably, in an optional technical solution of the present invention, the detection electrode is a strip electrode, the extension direction of the strip electrode is perpendicular to the linear electrode, and the extension distance spans multiple linear electrodes. This arrangement is compact, reduces the overall space occupation, and is beneficial to the miniaturization of the ion cyclotron resonance device.

[0017] Preferably, in an optional technical solution of the present invention, the detection electrode comprises 2n arc-shaped electrodes, n≥1, wherein the arc lengths of the arc-shaped electrodes are equal and they form a ring, and the circular surface of the arc-shaped electrodes is parallel to the circular surface of the cylindrical spatial region. The ring electrode formed by multiple arc-shaped electrode plates arranged end-to-end can selectively detect harmonic frequencies of a specific order, thereby obtaining a higher resolution spectrum.

[0018] In the optional technical solution of the present invention, n=2. Using four arc-shaped electrode plates to form a ring electrode, only the second harmonic can be obtained, the resolution of the spectrum is further improved, and the device is less complex and easier to manufacture compared with the device for analyzing higher harmonics.

[0019] In an optional embodiment of the present invention, the central region of the opposing surfaces of the magnets has a protrusion. Creating a protrusion in the central region of the opposing surfaces of the magnets allows the magnetic field strength in the central region to be significantly stronger than that in the outer peripheral region, thereby making it more effective in trapping ions entering the central region and increasing the degree of ion aggregation in spatial position.

[0020] In an optional embodiment of the present invention, an opening is provided in the central region of one of the magnets in the pair of magnets, and the opening serves as the ion inlet of the ion cyclotron resonance device.

[0021] This technical solution provides a sample introduction structure for an ion cyclotron resonance device. Because the sample introduction structure introduces the sample along the axial direction in the central region, and the surfaces of the magnetic poles are perpendicular to the direction of ion transport, the length of the ion cyclotron resonance device along the axial direction of the mass spectrometry system is shortened, making it convenient for the ion cyclotron resonance device to be used in the mass spectrometry system with less axial space.

[0022] In an optional embodiment of the present invention, the magnetic field strength gradually decreases from the central region to the outer periphery within the cylindrical spatial region. According to this embodiment, by configuring the magnetic field strength to have a continuous gradient, the binding force of the magnetic field on ions along the axial direction can be further enhanced.

[0023] In an optional embodiment of the present invention, the ion cyclotron resonance device operates in absorption mode. According to this optional embodiment, a mass spectrometer equipped with the ion cyclotron resonance device, such as an FT-ICR mass spectrometer, can implement absorption mode using a simpler apparatus.

[0024] In an optional embodiment of the present invention, the operating gas pressure of the ion cyclotron resonance device is lower than 10. -4 Pa, the magnetic field strength in the central region is 0.5-1.5 T.

[0025] According to this optional technical solution, the ion cyclotron resonance device can operate under low pressure. Compared with existing ion cyclotron resonance devices that require high vacuum conditions, this simplifies the vacuum system, making the ion cyclotron resonance device easier to miniaturize and saving space. Furthermore, the magnetic field strength in the central region is only 0.5-1.5T. Compared with existing technologies that require high magnetic field strength and uniformity to achieve higher resolution (often requiring superconducting coils to generate uniform magnetic fields of 10T or higher), the lower magnetic field strength requirement facilitates cost reduction and miniaturization of the mass spectrometry system. While meeting the miniaturization requirements, the mass spectrometry system using this ion cyclotron resonance device can provide better resolution than ion cyclotron resonance devices using the same or similar pressure conditions and magnetic field strength in existing technologies, thus more effectively balancing pressure conditions, magnetic field strength, and resolution requirements.

[0026] The present invention also provides a control method for an ion cyclotron resonance device, comprising the following steps: continuously injecting ions into a cylindrical spatial region through an opening; reducing the kinetic energy of the injected ions to zero by applying a voltage to an electrode array; and applying an alternating voltage to the electrode array to excite the cyclotron orbit of the ions from the central region to the outer peripheral region.

[0027] According to this technical solution, ions are continuously injected along the axial direction. Then, through voltage control of the electrode array, such as controlling the applied DC deceleration voltage, the kinetic energy of a certain number of ions located in suitable internal positions is reduced to almost zero. The deceleration voltage is then removed and an alternating voltage is reapplied, exciting the ions' cyclotron trajectory from the central region to the outer periphery. Some ions are excited and detected (other ions are lost). The control program for this continuous ion injection is relatively simple to set.

[0028] The present invention also provides a control method for an ion cyclotron resonance device. The control method has multiple working cycles, and each working cycle performs the following steps: compressing ions into ion packets and injecting the ion packets into a cylindrical spatial region through an opening; reducing the kinetic energy of the ions in the injected ion packets to zero by applying a voltage to an electrode array; and applying an alternating voltage to the electrode array to excite the cyclotron orbit of the ions in the ion packets from the central region to the outer peripheral region.

[0029] According to this technical solution, ions are not continuously injected, but rather compressed into multiple ion packets according to different time intervals, and then pulsedly injected into the ion cyclotron resonance device. Specifically, firstly, the voltage on the electrode array can be controlled, for example, by controlling the applied DC deceleration voltage, so that the kinetic energy of the ions in the ion packets is reduced to almost zero. Then, the deceleration voltage is removed, and an alternating voltage is applied to excite and detect the cyclotron orbits of the ions from the central region to the outer periphery. By pulsedly injecting ions, more ions can be detected (theoretically, all ions can be detected), thereby increasing the duty cycle achievable by the mass spectrometry system composed of this ion cyclotron resonance device.

[0030] The present invention also provides a mass spectrometer having the aforementioned ion cyclotron resonance device. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the ion cyclotron resonance device in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram illustrating the relationship between the ion cyclotron motion trajectory and the second magnetic pole plane and the second electrode array in an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram showing the positional relationship between the flat plate electrode and the first electrode array and the second electrode array in an embodiment of the present invention.

[0034] Figure 4 This is a mass spectrum obtained by detection using a strip electrode in an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram showing the positional relationship between the annular electrode and the first electrode array and the second electrode array in an embodiment of the present invention.

[0036] Figure 6 This is a mass spectrum obtained by detection using a circular electrode in an embodiment of the present invention.

[0037] Figure 7 This is a schematic diagram showing the positional relationship between the dipole ring electrode and the first electrode array and the second electrode array in an embodiment of the present invention.

[0038] Figure 8This is a mass spectrum obtained by detection using a dipole circular electrode in an embodiment of the present invention.

[0039] Figure 9 This is a schematic diagram of a structure in an embodiment of the present invention, showing a protrusion in the central region of the first magnetic pole plane and the second magnetic pole plane.

[0040] Figure 10 This is a schematic diagram showing the positional relationship between the opening and the first magnetic pole plane in an embodiment of the present invention.

[0041] Figure 11 This is a schematic diagram of ion incident and excitation in an embodiment of the present invention.

[0042] Figure 12 This is a schematic diagram of a control method for an ion cyclotron resonance device in an embodiment of the present invention.

[0043] Figure 13 This is a schematic diagram of another control method for the ion cyclotron resonance device in an embodiment of the present invention.

[0044] Figure 14 This is a schematic diagram of the mass spectrometer in an embodiment of the present invention.

[0045] Figure label:

[0046] Cylindrical spatial region CS; magnet M1; magnet M2; first magnetic pole plane 1; opening 11; protrusion 12; second magnetic pole plane 2; first electrode array 3; linear electrode 30; second electrode array 4; linear electrode 40; flat plate electrode 51; ring electrode 52; dipole ring electrode 53; mass spectrometer 6; ion cyclotron resonance device 61; ion source 62; first ion guiding device 63; second ion guiding device 64; ion lens 65. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Please see Figure 1 , Figure 2 As shown, this embodiment provides an ion cyclotron resonance device for mass spectrometry analysis, including a cylindrical spatial region CS for ion introduction, excitation and detection. Figure 1 The image shows a longitudinal section of the cylindrical spatial region CS. Figure 2The image shows a cross-section of the cylindrical spatial region CS. During ion excitation, ions are excited radially outward from the center of the cylindrical spatial region CS. Figure 2 This is a schematic diagram of the trajectory of ions excited radially outward from the center of the cylindrical spatial region CS in this embodiment. It should be noted that the direction of the ion's movement path is not strictly defined by radial outward excitation, as long as the ion's movement path after being excited has a radial outward velocity component.

[0049] Regarding the magnetic field, the ion cyclotron resonance device in this embodiment includes a pair of magnets, namely magnet M1 and magnet M2. The opposing surfaces of these magnets, namely the first magnetic pole plane 1 and the second magnetic pole plane 2, are both perpendicular to the axial direction. The first magnetic pole plane 1 and the second magnetic pole plane 2 are parallel to each other and have opposite polarities. In other words, if the first magnetic pole plane 1 is the S pole of magnet M1, then the second magnetic pole plane 2 corresponds to the N pole of magnet M2; if the first magnetic pole plane 1 is the N pole of magnet M1, then the second magnetic pole plane 2 corresponds to the S pole of magnet M2. The magnetic field strength in the central region of the first magnetic pole plane 1 and the second magnetic pole plane 2 is greater than the magnetic field strength in the outer peripheral region.

[0050] Regarding the electric field, the ion cyclotron resonance device provided in this embodiment includes two sets of electrode arrays, namely a first electrode array 3 and a second electrode array 4. Both the first electrode array 3 and the second electrode array 4 are formed by multiple electrodes arranged along a specific plane. Figure 1 The diagram shows a cross-sectional view of the first electrode array 3 and the second electrode array 4. Figure 1 It can be seen that the first electrode array 3 is arranged on a plane perpendicular to the axial direction, and the second electrode array 4 is also arranged on a plane perpendicular to the axial direction, that is, the arrangement directions of the first electrode array 3 and the second electrode array 4 are parallel to each other. The number and placement of the electrodes included in the second electrode array 4 correspond to those of the first electrode array 3. Both the first electrode array 3 and the second electrode array 4 are disposed between the first magnetic pole plane 1 and the second magnetic pole plane 2.

[0051] refer to Figure 2 An alternating voltage is applied between the first electrode array 3 and the second electrode array 4. Ions located between the first electrode array 3 and the second electrode array 4 are excited by the alternating electric field formed by the alternating voltage, and their cyclotron orbits are excited from the central region to the outer peripheral region.

[0052] In this embodiment of the invention, the magnetic field strength in the central region is greater than that in the outer region. This magnetic field distribution, which is strong in the center and weak around the periphery, abandons the inherent bias that ion cyclotron resonance devices should use a uniform magnetic field. It utilizes the radial gradient of the magnetic field strength to bind ions along the axial direction, thereby eliminating the need for the DC electrostatic field used in the prior art to generate the axial binding force and avoiding the distortion of the excitation electric field caused by the additional DC electrostatic field.

[0053] Furthermore, the strong magnetic field in the central region can effectively bind and compress a certain amount of ions in the central region of the ion cyclotron resonance device without the application of an excitation electric field, making the ion aggregation effect more obvious and facilitating detection by the detection electrode. Moreover, because the first magnetic pole plane 1, the second magnetic pole plane 2, the first electrode array 3, and the second electrode array 4 are all planar structures arranged parallel to each other, this structure of the ion cyclotron resonance device is easy to manufacture, effectively reducing processing costs.

[0054] Because there is no distortion of the excitation electric field, even with reductions in detection time, equipment vacuum level, and magnetic field strength, the detection resolution of the ion cyclotron resonance device can still meet the needs of daily testing. In particular, this ion cyclotron resonance device can be used as a detector for benchtop or portable mass spectrometers, satisfying the aforementioned requirements of mass spectrometers for detection time, vacuum level, magnetic field strength, and resolution.

[0055] In this embodiment, the first magnetic pole plane 1 and the second magnetic pole plane 2 have opposite polarities, namely N pole and S pole, or S pole and N pole, respectively. The magnetic pole plane can be a planar portion with a single polarity at the end of the magnet. Preferably, both magnets M1 and M2 are permanent magnets. In some embodiments, magnets M1 and M2 can also be electromagnets or single-sided magnets, and the first magnetic pole plane 1 and the second magnetic pole plane 2 can also be the magnetic pole plane of an electromagnet or the magnetic pole plane of a single-sided magnet with stronger magnetism. This embodiment of the invention does not impose any limitations on these aspects.

[0056] The first magnetic pole plane 1 and the second magnetic pole plane 2 are preferably magnetic pole planes of permanent magnets, specifically the end faces of permanent magnets with a single polarity. On one hand, for widely used cylindrical permanent magnets and disk-shaped permanent magnets that are uniformly magnetized along the axial direction, the field strength in the central region of their two end faces is usually stronger than that in the outer peripheral region. Therefore, by simply placing the end faces of opposite magnetic poles of two permanent magnets of essentially the same shape and size facing each other, a magnetic pole plane that satisfies the magnetic field strength distribution conditions defined in the embodiments of this invention can be formed, making the magnetic pole fabrication very simple. Furthermore, using permanent magnets to generate the ion rotation magnetic field eliminates the need for separate power supplies and other external equipment, effectively reducing equipment and maintenance costs. Compared to the prior art of obtaining a uniform strong magnetic field through large-volume superconducting magnets, using permanent magnets to generate the magnetic field makes it possible to miniaturize FT-ICR to tabletop or even portable sizes.

[0057] Furthermore, in the above-described structure where permanent magnets are arranged opposite each other, the magnetic field strength in the cylindrical spatial region CS gradually decreases from the central region to the outer periphery. That is, along the direction from the central region to the outer periphery, the magnetic field strength is configured with a continuous gradient, which can further enhance the magnetic field's binding force on ions in the axial direction.

[0058] Continue to refer to Figure 1 and Figure 2 In this embodiment, both the first electrode array 3 and the second electrode array 4 are aligned with the circular surface of the cylindrical spatial region CS (i.e., Figure 1 The left and right end faces of the cylindrical spatial region are parallel. The first electrode array 3 and the second electrode array 4 each include multiple parallel and equally spaced linear electrodes 30 and 40. The first electrode array 3 and / or the second electrode array 4 can be constructed from metal lines on the surface of a PCB circuit board. Fabricating the first electrode array 3 and / or the second electrode array 4 using PCB technology can reduce the manufacturing cost of the first electrode array 3 and / or the second electrode array 4, and is particularly convenient for the production of miniaturized ion cyclotron resonance devices.

[0059] Specifically, multiple linear electrodes 30 are arranged parallel to each other and with equal spacing, and multiple linear electrodes 40 are also arranged parallel to each other and with equal spacing. Furthermore, the linear electrodes of the parallel first electrode array 3 and the second electrode array 4 are arranged in pairs. This arrangement of electrodes helps to provide a more uniform excitation electric field. Moreover, these regular linear electrodes are easy to process, especially easy to form using PCB technology or gold finger technology, further reducing processing costs.

[0060] like Figure 3As shown, in this embodiment, the ion cyclotron resonance device further includes a detection electrode disposed between the first electrode array 3 and the second electrode array 4. The detection electrode is used to detect the mirror current and consists of two opposing strip electrodes 51. The extension direction of the strip electrode 51 is perpendicular to the linear electrodes 30 and 40, and the strip electrode 51 spans multiple linear electrodes 30 and 40. In some embodiments, the strip electrode 51 may also be disposed between two adjacent linear electrodes, for example, between the two middle linear electrodes.

[0061] The detection electrode is used to detect the mirror current. The detection electrode structure composed of two strip electrodes 51 is simpler, and the overall structure of the ion cyclotron resonance device is more compact, occupies less space, and is easy to miniaturize.

[0062] Interference caused by the shielding effect of the electric field Figure 4 The mass spectrum obtained using strip electrode 51 is from... Figure 4 As can be seen, in addition to the first harmonic corresponding to the main peak, the spectrum also contains higher-order harmonics such as the second and fourth harmonics. To eliminate interference from higher-order harmonics and simplify the spectrum data for easier analysis, such as... Figure 5 As shown, in a preferred embodiment of the present invention, the detection electrode can also be a ring electrode 52. Specifically, the ring electrode 52 is formed by arranging 2n (n≥1) arc-shaped electrodes of equal arc length end-to-end. Each arc-shaped electrode has an equal arc length and forms a ring, with the circular surface of the arc-shaped electrode parallel to the circular surface of the cylindrical spatial region CS. Using a ring electrode 52 formed by arranging multiple arc-shaped electrodes end-to-end, harmonic frequencies of a specific order can be detected, resulting in a spectrum with higher resolution.

[0063] More preferably, refer to Figure 5 The annular electrode 52 consists of four arc-shaped electrode plates, i.e., n = 2. Figure 6 yes Figure 5 The mass spectrum obtained from the ion cyclotron resonance device structure shown. (Reference) Figure 6 It can be seen that the detection electrode of this ion cyclotron resonance device can detect only the second harmonic, with high resolution.

[0064] In some embodiments, a higher-order annular electrode 52 can be used as the detection electrode to obtain a higher resolution mass spectrum, but this results in a more complex structure for the ion cyclotron resonance device and increased manufacturing costs. In comparison, the annular electrode 52 composed of four arc-shaped electrodes is a more preferred solution, which can balance the requirements of resolution and device cost.

[0065] like Figure 7 , Figure 8As shown, in some other embodiments, the detection electrode can also be composed of a dipole ring electrode 53, i.e., n=1. The detection electrode composed of the dipole ring electrode 53 can remove higher harmonics in the obtained mass spectrum, and only the first harmonic is obtained.

[0066] Figure 9 This is a schematic diagram of the structure of an ion cyclotron resonance device according to a preferred embodiment of the present invention. Specifically, as shown... Figure 9 As shown, in a preferred embodiment of the present invention, the central region of magnet M1 or magnet M2 has a protrusion 12. Specifically, in this embodiment, the first magnetic pole plane 1 of magnet M1 is provided with a protrusion 12 protruding towards the second magnetic pole plane 2. The provision of the protrusion 12 can reduce the spacing between the magnetic pole planes in the central region, increase the magnetic flux density, and make the magnetic field strength significantly stronger than that in the outer region. This is more conducive to confining ions entering the central region, ensuring that the ions are relatively concentrated in space and have good phase uniformity. Simulation results show that, using the ion cyclotron resonance device with this structure, the cyclotron trajectory of ions can be effectively confined within a thin plane of a limited size, and a spectral resolution of 4k can be achieved under the conditions of a magnetic field strength of 1T and a detection time of 50ms.

[0067] like Figure 10 As shown, in a preferred embodiment of the present invention, an opening 11 is provided in the central region of the first magnetic pole plane 1 or the second magnetic pole plane 2, and the opening 11 serves as the ion inlet of the ion cyclotron resonance device. Specifically, the opening 11 can be a through hole with a large diameter, or a vacuum interface such as a conical hole or orifice.

[0068] In some embodiments of the present invention, the ion cyclotron resonance device operates in absorption mode.

[0069] In Fourier transform-cyclotron resonance mass spectrometry (FT-ICR), the actual measured signal is a time-domain signal (time-ion current signal). This time-domain signal is converted to a frequency-domain signal (frequency-ion current signal) through Fourier transform. Because frequency and mass-to-charge ratio (m / z) have a one-to-one correspondence, a mass spectrum (i.e., m / z-ion current signal) is obtained. The default operating mode of FT-ICR is amplitude mode, which directly represents the converted ion current using the amplitude (the ion current obtained after Fourier transform is a complex number containing real and imaginary parts; the amplitude is the square root of the real and imaginary parts).

[0070] Fourier transform-cyclotron resonance mass spectrometers also include absorption mode, which uses the real part to represent the converted ion current. Theoretically, absorption mode can achieve higher resolution than amplitude mode (1.5 to 2 times the resolution of amplitude mode), but this is on the premise that all ions are in the same phase at the beginning (i.e. before detection). Therefore, in order to use absorption mode, FT-ICR must perform relatively complex phase correction, which increases the complexity of the device.

[0071] In the embodiments of the present invention, since all ions enter through opening 11 and are immediately bound by the high magnetic field strength in the central region, the ions are relatively concentrated in space, resulting in good phase uniformity. Even without phase correction, the absorption mode can be used in a limited way, such as when the mass range is narrow and the ion phase difference is small. Through this method, although the ion cyclotron resonance device adopts a very simplified structure, it can still use the absorption mode without phase correction.

[0072] In the above embodiments of the present invention, the operating gas pressure of the ion cyclotron resonance device is lower than 10. -4 The magnetic field strength in the central region of the first magnetic pole plane 1 and the second magnetic pole plane 2 is 0.8-1.5T.

[0073] Through the above method, the ion cyclotron resonance device can operate under low pressure. Compared with existing ion cyclotron resonance devices that require high vacuum conditions, this simplifies the vacuum system, making the ion cyclotron resonance device easier to miniaturize and saving space. Furthermore, the magnetic field strength in the central region of the first magnetic pole plane 1 and the second magnetic pole plane 2 is only 0.8-1.5T. Compared with existing technologies that require high magnetic field strength and uniformity to achieve higher resolution (often requiring superconducting coils to generate uniform magnetic fields of 10T or higher), the lower magnetic field strength requirement also facilitates cost reduction and miniaturization of the mass spectrometry system. While meeting the miniaturization requirements, the mass spectrometry system using this ion cyclotron resonance device can provide a higher resolution than ion cyclotron resonance devices using the same or similar pressure conditions and magnetic field strengths in existing technologies, thus more effectively balancing pressure conditions, magnetic field strength, and resolution requirements.

[0074] like Figure 12 As shown, an embodiment of the present invention further provides a control method for an ion cyclotron resonance device, applicable to an ion cyclotron resonance device having an opening 11 in the central region of a first magnetic pole plane 1 or a second magnetic pole plane 2, comprising the following steps:

[0075] S1, through opening 11, continuously injects ions into the cylindrical space region CS between the first electrode array 3 and the second electrode array 4;

[0076] S2, by applying a voltage between the first electrode array 3 and the second electrode array 4, the kinetic energy of the injected ions is reduced to zero;

[0077] S3, applying an alternating voltage between the first electrode array 3 and the second electrode array 4 to excite the ions to rotate from the central region to the outer peripheral region.

[0078] Specifically, such as Figure 11 As shown and combined Figure 2 Ions enter the central region of the magnetic field through opening 11. Under the influence of the alternating electric field, the ions are excited and undergo cyclotron motion. Figure 11 The circles between the first electrode array 3 and the second electrode array 4 indicate the possible locations where ions may appear.

[0079] In this method, ions are continuously implanted along the axial direction. Then, at a certain moment, a reverse DC voltage along the axial direction is applied, causing the kinetic energy of a certain number of ions located in suitable internal positions to slow down or decrease to zero. The reverse DC voltage used for deceleration is then removed, and an alternating voltage is applied, exciting the ions' cyclotron trajectory from the central region to the outer periphery. Some ions will be excited and detected. The advantage of continuous ion implantation is that the operation is very simple.

[0080] like Figure 13 As shown, this invention also provides a control method for an ion cyclotron resonance device, applicable to ion cyclotron resonance devices with an opening 11 in the central region of a first magnetic pole plane 1 or a second magnetic pole plane 2. One analysis process of this control method includes multiple working cycles, each working cycle executing the following steps:

[0081] S4, ions are compressed into ion packets and injected into the cylindrical space region CS between the first electrode array 3 and the second electrode array 4 through the opening 11.

[0082] S5, by applying a voltage between the first electrode array 3 and the second electrode array 4, the kinetic energy of the ions in the injected ion pack is reduced to zero;

[0083] S6, an alternating voltage is applied between the first electrode array 3 and the second electrode array 4 to excite the ions in the ion pack to rotate from the central region to the outer peripheral region.

[0084] In this method, ions are not injected continuously, but rather compressed into multiple ion packets according to different time intervals, and then injected into the magnetic field in a pulsed manner. One continuous time interval corresponds to one ion packet, and multiple time intervals can be of equal or unequal length.

[0085] Specifically, firstly, a reverse DC voltage is applied along the axial direction to reduce the kinetic energy of the ions within the ion pack until it reaches zero. Then, the reverse DC voltage used to decelerate the ions is removed, and an alternating voltage is applied to excite the ions' cyclotron orbits from the central region to the outer periphery. These ions are then excited and detected. The advantage of pulsed ion implantation is that almost all incoming ions can be detected, and the duty cycle of mass spectrometry analysis is high.

[0086] like Figure 14 As shown, in this embodiment of the invention, a mass spectrometer 6 is also provided, which has the aforementioned ion cyclotron resonance device 61.

[0087] Furthermore, the mass spectrometer 6 provided in this embodiment of the invention also includes an ion source 62, a first ion guiding device 63, a second ion guiding device 64, and an ion lens 65. The structures of the ion source 62, the first ion guiding device 63, the second ion guiding device 64, and the ion lens 65 are common applications in the art and will not be described in detail here. Additionally, the vacuum level required for the operation of the ion cyclotron resonance device 61 of this invention is generally still below 10. -4 Therefore, a series of vacuum devices are needed in the pre-stage to gradually reduce the gas pressure, but this is still less than the 10 Pa required by existing FT-ICR mass spectrometers. -7 Under the pressure conditions of Pa, the FT-ICR mass spectrometer provided in this embodiment of the invention still has very low requirements for vacuum, which can save manufacturing costs and floor space.

[0088] It should be noted that in this disclosure, terms such as "perpendicular" and "parallel" used to describe positional relationships do not represent a strict mathematical geometric relationship; it is sufficient that the two are substantially perpendicular or substantially parallel as a whole.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ion cyclotron resonance device for mass spectrometry analysis, characterized in that, include A cylindrical spatial region for ion introduction, excitation and detection, wherein during the ion excitation process, ions are excited radially outward from the center of the cylindrical spatial region; A pair of magnets are placed parallel to the axial direction of the cylindrical spatial region to generate a magnetic field within the spatial region. The opposing surfaces of the magnets are perpendicular to the axial direction, and the magnetic field strength in the central region of the spatial region is greater than the magnetic field strength in the radially peripheral region. An electrode array is disposed between the pair of magnets, and an alternating voltage is applied to the electrodes of the electrode array to excite ions.

2. The ion cyclotron resonance device as described in claim 1, characterized in that, The magnet is a permanent magnet.

3. The ion cyclotron resonance device as described in claim 1, characterized in that, The electrode array comprises two sets of electrode arrays arranged parallel to the circular surface of the cylindrical spatial region, each set of electrode arrays comprising multiple parallel and equally spaced linear electrodes.

4. The ion cyclotron resonance device as described in claim 3, characterized in that, It also includes at least two detection electrodes disposed between the pair of magnets for performing mirror current detection of ions.

5. The ion cyclotron resonance device as described in claim 4, characterized in that, The detection electrode is a strip electrode, the extension direction of which is perpendicular to the linear electrode, and the extension distance spans multiple linear electrodes.

6. The ion cyclotron resonance device as described in claim 4, characterized in that, The detection electrode includes 2n arc-shaped electrodes, n≥1, the arc lengths of the arc-shaped electrodes are equal and they form a ring, and the circular surface of the arc-shaped electrodes is parallel to the circular surface of the cylindrical spatial region.

7. The ion cyclotron resonance device as described in claim 6, characterized in that, n＝2。 8. The ion cyclotron resonance device as described in claim 1, characterized in that, The central region of the opposing surfaces of the pair of magnets has a protrusion.

9. The ion cyclotron resonance device as described in claim 1 or 8, characterized in that, An opening is provided in the central region of one of the pair of magnets, which serves as the ion inlet of the ion cyclotron resonance device.

10. The ion cyclotron resonance device as described in claim 1, characterized in that, Within the cylindrical spatial region, the magnetic field strength gradually decreases from the central region to the outer periphery.

11. The ion cyclotron resonance device as described in claim 1, characterized in that, The ion cyclotron resonance device operates in absorption mode.

12. The ion cyclotron resonance device as described in claim 1, characterized in that, The operating pressure of the ion cyclotron resonance device is below 10. -4 Pa, the magnetic field strength of the central region is 0.5-1.5T.

13. A control method for an ion cyclotron resonance device as described in claim 9, characterized in that, Includes the following steps: Ions are continuously injected into the cylindrical space region through the opening; By applying a voltage to the electrode array, the kinetic energy of the injected ions is reduced to zero; An alternating voltage is applied to the electrode array to excite ions to rotate from the central region to the outer peripheral region.

14. A control method for an ion cyclotron resonance device as described in claim 9, characterized in that, The control method has multiple working cycles, and each working cycle executes the following steps: Ions are compressed into ion packets, and the ion packets are injected into the cylindrical space region through the opening; By applying a voltage to the electrode array, the kinetic energy of the ions in the injected ion pack is reduced to zero; An alternating voltage is applied to the electrode array to excite the ions in the ion pack to rotate from the central region to the outer peripheral region.

15. A mass spectrometer, characterized in that, The mass spectrometer has an ion cyclotron resonance device as described in any one of claims 1-12.

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