Mass spectrometry ion transport system and method of controlling the same

Abstract

The application relates to a mass spectrum ion conveying system arranged in an ion channel of a mass spectrometer, wherein the ion channel is provided with an ion inlet and an ion outlet, and the mass spectrum ion conveying system comprises: a plurality of coaxially arranged sheet-shaped ring electrodes, the plurality of sheet-shaped ring electrodes are spliced to form an ion conveying channel, the ion conveying channel sequentially forms a focusing section and a collecting section along an ion conveying direction, and a sheet-shaped transition ring electrode is connected between the focusing section and the collecting section; a funnel converging electrode which is communicated with the collecting section is arranged at the ion outlet; the funnel converging electrode is composed of a plurality of coaxially spliced conical sheet-shaped electrodes, and the sheet-shaped ring electrode, the sheet-shaped transition ring electrode and the conical sheet-shaped electrode are all provided with independent voltage connection entrances. The ion conveying channel is designed as a calabash-shaped structure composed of the focusing section and the collecting section, the initial capture range of ions is greatly increased in the focusing section, the wide-range preliminary focusing of ions is realized, and the scattered ions in the preliminary focusing process are accurately captured and secondarily focused in the collecting section.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometer supporting systems, and more specifically, to a mass spectrometer ion delivery system and its control method. Background Technology

[0002] A mass spectrometer is a precision analytical instrument that performs qualitative and quantitative analysis of compounds by measuring the mass-to-charge ratio of ions. The ion transport system, as the core functional component of the ion channel of the mass spectrometer, plays a crucial role in ion capture, focusing, and directional transport to the mass analyzer. Its ion capture efficiency and transport efficiency directly determine the sensitivity, accuracy, and detection limit of mass spectrometry detection, and are the core factors affecting the overall performance of the mass spectrometer.

[0003] In existing technologies, ion transport devices for mass spectrometers mostly employ a single conical or cylindrical ion funnel structure. This type of structure has several technical drawbacks: First, the ion inlet is designed with a constant diameter, limiting the initial ion capture range. Furthermore, it easily generates stray ions during the initial focusing process, which existing structures cannot effectively recover, resulting in a low ion capture rate and directly affecting the sensitivity of mass spectrometry detection. Second, the electrodes of traditional ion funnels are mostly integrally molded structures with a fixed and non-adjustable electrode spacing. This makes it impossible to specifically adapt to the ion transport characteristics of different mass-to-charge ratios and ionization methods, resulting in poor device adaptability and significant differences in transport efficiency for different types of ions, making it difficult to meet the needs of mass spectrometry for various scenarios and types of compounds. The first issue is the demand for mass spectrometry detection. Secondly, the assembly of some ion funnels with the ion channels of mass spectrometers is cumbersome. During assembly, it is difficult to ensure the coaxial alignment accuracy of the electrode components with the ion transport system and mass analyzer of the mass spectrometer. Coaxiality deviations cause additional losses during ion transport, further reducing ion transport efficiency. Thirdly, while existing composite ion funnels have improved upon single-structure designs, they still do not solve the core problems of insufficient ion capture and ineffective recovery of stray ions from a structural design perspective. Furthermore, some devices have overly complex structural designs, increasing the difficulty of installation, debugging, and maintenance, and failing to meet the practical application requirements of mass spectrometry for high capture rate, high transport efficiency, high adaptability, and convenient assembly of ion transport devices.

[0004] To address the aforementioned technical challenges, developing a mass spectrometry ion delivery system that can effectively increase the ion capture range, achieve the recovery and secondary focusing of stray ions, and allows for precise adjustment in three dimensions—electrode spacing, number of electrodes, and electrode diameter—along with a suitable gourd-shaped structure for precise voltage application and a segmented gradient pressurization structure for the beam-closing electrodes, is a crucial technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To achieve the objectives of this invention, the technical solution adopted is as follows: a mass spectrometry ion delivery system, disposed within the ion channel of a mass spectrometer, the ion channel having an ion inlet and an ion outlet, comprising: multiple coaxially arranged sheet-like annular electrodes, the multiple sheet-like annular electrodes being spliced ​​together to form an ion delivery channel, the ion delivery channel sequentially forming a focusing section and a collecting section along the ion delivery direction, the focusing section and the collecting section being connected by a sheet-like transition annular electrode; a funnel-shaped convergence electrode connected to the collecting section is provided at the ion outlet; the funnel-shaped convergence electrode is composed of multiple coaxially spliced ​​conical sheet-like electrodes, with a first ceramic insulating pad between adjacent conical sheet-like electrodes, the whole assembly forming a conical output channel with an inner diameter gradually narrowing along the ion delivery direction; each of the sheet-like annular electrodes, the sheet-like transition annular electrode, and the conical sheet-like electrode has an independent voltage input, and each voltage input is electrically connected to the control system of the mass spectrometer.

[0006] Preferably, the inner diameter of the transport channels in both the focusing section and the collecting section increases first and then contracts along the ion transport direction, forming a two-stage gourd-shaped cavity structure.

[0007] Preferably, a second ceramic insulating pad is provided between adjacent sheet-like circular electrodes.

[0008] Preferably, multiple conical sheet electrodes are spliced ​​together to form an output channel, and the cone angle of the output channel is 15°.

[0009] Preferably, multiple high-resistivity ion current probes are radially and uniformly installed at three locations: the end of the focusing section, the end of the collecting section, and the outlet of the ion delivery channel. The high-resistivity ion current probes penetrate deep into the inner wall of the channel and do not collide or interfere with the ion beam.

[0010] Preferably, a control method for a mass spectrometry ion delivery system includes: S1: Parameter matching based on the ion to be detected; S2: Adjust the assembly according to the matched parameters; S3: Electric field loading and ion transport driven by segmented gradient voltage; Among them, through multiphysics simulation and extensive experimental fitting, the relationship between ion capture efficiency η and electrode voltage, electrode spacing and number of electrodes is established, so as to realize that parameter design is calculable, predictable and verifiable. η = η0 × 1 / (1 + e^(-k1×ΔU)) × 1 / (1 + e^(-k2×N / L)) × 1 / (1 +e^(k3×(D-D0))); The parameters in the formula are defined as follows: η: total ion capture efficiency (0–1); η0: ideal structure limiting capture efficiency (0.95–0.99); ΔU: total voltage rise from the inlet to the end of the focusing section; N / L: number of electrodes per unit length; D: electrode spacing; D0: optimal electrode spacing for mass-to-charge ratio ions; k1, k2, k3: fitting coefficients (calibrated experimentally, k1≈0.02–0.05, k2≈0.3–0.8, k3≈1.2–3.0); Voltage term: 1 / [1+exp (-k1・ΔU)], the higher the voltage, the higher the capture efficiency, approaching saturation; Density term: 1 / [1+exp (-k2・N / L)], the denser the electrodes, the more stable the constraint and the higher the efficiency; Spacing term: 1 / [1+exp (k3・(D-D0))], the further the spacing deviates from D0, the faster the efficiency decreases; S4: Controlling the radial direction of ions; Preferably, a simplified judgment formula is used for rapid on-site judgment; η≈C0 + C1・ΔU - C2・|D-D0| + C3・N / L; Where η: total ion capture efficiency (0–1); ΔU: total voltage rise from the inlet to the end of the focusing section; D: electrode spacing; D0: optimal electrode spacing for mass-to-charge ratio ions; N / L: number of electrodes per unit length; C0 is the basic capture efficiency constant, which represents the basic efficiency value that the system can achieve under conditions of no voltage, no electrode density, and optimal spacing. C1 is the voltage term coefficient, which represents the degree to which the capture efficiency η improves for every 1V increase in the total voltage rise ΔU; C2 is the spacing deviation penalty coefficient. When the actual electrode spacing D deviates from the optimal spacing D0, the efficiency decreases by approximately 1 mm for every deviation. C3 is the electrode density gain coefficient, which represents the effect of changing the electrode density (N / L) on improving the capture efficiency.

[0011] Suitable for rapid estimation in linear intervals, with an error of <8%.

[0012] Preferably, the current signal of the high-resistivity ion current probe is acquired: Dispersion S = (I max - I min ) / I max × 100%, threshold S>15% triggers adjustment; Among them, I max I is the maximum current. min Minimum current; Gaussian fitting was performed on the current distribution to obtain the beam waist diameter FWHM, and the standard deviation σ of 10 consecutive sets of data was calculated. D Adjustment is triggered when the diameter is > 0.2mm; FWHM ≈ 2.355 × W; W: Waist radius; σ D It is the standard deviation of 10 consecutive sets of FWHM data; if σ D > 0.2 mm indicates that the measurement results of the waist diameter have a large degree of dispersion, and the system stability or repeatability may be insufficient; Simultaneously, the center offset is determined by the ratio of the probe current to the relative position. A deviation of >10% indicates an asymmetric electric field or electrode assembly error. Density uniformity is determined by the coefficient of variation (CV); a CV < 10% indicates uniformity. Wherein, CV = (standard deviation of multi-probe current / mean current) × 100%.

[0013] Preferably, the system executes a differentiated adjustment strategy based on the combination characteristics of the triggering conditions: When the dispersion S > 15% and the waist fluctuation σ D When the value is less than 0.1 mm, it is determined that the radial constraint is insufficient, and the voltage gradient of this segment is increased to enhance the constraint. When S>15% and σ D When the value is >0.2mm, it is determined that the ion beam has a "breathing" jitter effect. The voltage of the preceding section should be checked and stabilized first before fine-tuning this section. When S>15% and center offset>10%, it is determined that the assembly or electric field is asymmetrical, triggering an alarm to check the coaxiality of the electrodes and the consistency of the voltage on the left and right sides. When the density uniformity CV > 10%, it is determined that the ion beam is locally too dense. The gradient of this section should be appropriately reduced and the diameter expansion length of the preceding section should be increased.

[0014] The beneficial effects of the invention are: 1. The ion transport channel is designed as a gourd-shaped structure consisting of a focusing section and a collection section. The focusing section greatly increases the initial ion capture range, achieving wide-range initial focusing of ions. The collection section accurately captures and refocuses the escaping ions during the initial focusing process. The structural design solves the problems of insufficient ion capture and inability to recover escaping ions in the existing technology.

[0015] 2. The funnel-shaped beam-closing electrode is a conical sheet electrode that is precisely aligned with the mass analyzer of the mass spectrometer. The cone angle and the number of electrodes can be adjusted according to the diameter parameter of the end of the collection section and the ion mass-to-charge ratio, in conjunction with the unidirectional directional beam-closing electric field formed by the gradient pressure rise along the process.

[0016] 3. The sheet-shaped circular electrode, the sheet-shaped transition circular electrode, and the conical sheet electrode are all equipped with independent voltage inputs and are electrically connected to the programmable power control system to achieve independent, precise, and real-time voltage adjustment, and can quickly match the pressure strategy according to the ion type.

[0017] 4. By radially and evenly installing multiple high-resistivity ion current probes at the ends of the focusing section, the collection section, and the ion transport channel outlet, and combining them with the detection method, a segmented, independent, and progressively optimized voltage feedback regulation method is formed. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the mass spectrometry ion delivery system of the present invention; Figure 2 This is a cross-sectional view of the overall structure of the mass spectrometry ion delivery system of the present invention; Figure 3 This is a schematic diagram of the overall structure of the funnel-shaped convergence electrode of the present invention; Figure 4 This is a system block diagram of the mass spectrometry ion delivery system of the present invention; In the figure: 1. Sheet-shaped circular electrode; 101: Ion transport channel; 2. Funnel-shaped convergence electrode; 201. Conical sheet-shaped electrode; 3. Sheet-shaped transition circular electrode. Detailed Implementation

[0019] 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.

[0020] Example 1: like Figures 1 to 3 As shown, a mass spectrometry ion delivery system is applied in the ion channel of a mass spectrometer to achieve efficient ion capture, focusing and directional transport, and is adapted to mass spectrometry detection scenarios with various ionization methods such as electrospray ionization.

[0021] A mass spectrometry ion delivery system is installed in the ion channel of a mass spectrometer. The ion channel has an ion inlet and an ion outlet, including: multiple coaxially arranged sheet-like annular electrodes 1, which are spliced ​​together to form an ion delivery channel 101. The ion delivery channel 101 forms a focusing section and a collecting section in sequence along the ion delivery direction. A sheet-like transition annular electrode 3 is connected between the focusing section and the collecting section. A funnel-shaped beam-gathering electrode 2 connected to the collecting section is provided at the ion outlet.

[0022] The inner diameter of the transport channels in both the focusing and collecting sections increases and then contracts along the ion transport direction, forming a two-stage gourd-shaped cavity structure.

[0023] A second ceramic insulating pad is provided between adjacent sheet-shaped circular electrodes 1.

[0024] The funnel-shaped converging electrode 2 is composed of multiple coaxially spliced ​​conical sheet electrodes 201. A first ceramic insulating pad is provided between adjacent conical sheet electrodes 201. The first ceramic insulating pad is an ultra-thin ceramic insulating pad (thickness 0.05mm-0.2mm).

[0025] The entire assembly forms a tapered output channel with an inner diameter that gradually narrows along the ion transport direction; the outlet diameter of the output channel is precisely matched with the ion inlet diameter of the mass spectrometer mass analyzer.

[0026] The sheet-shaped circular electrode 1, the sheet-shaped transition circular electrode 3, and the conical sheet-shaped electrode 201 are all provided with independent voltage inputs, and the voltage inputs are all electrically connected to the control system of the mass spectrometer.

[0027] The sheet-shaped circular electrode 1, the sheet-shaped transition circular electrode 3, and the conical sheet electrode 201 are all equipped with independent voltage inputs, and all voltage inputs are electrically connected to the programmable power control system of the mass spectrometer, so as to realize independent, precise, and gradient application of voltage. The voltage application strategy can be adjusted in real time according to the electrode structure parameters and the ion mass-to-charge ratio.

[0028] Multiple conical sheet electrodes 201 are spliced ​​together to form an output channel, and the cone angle of the output channel is 15°.

[0029] The outer diameters of the sheet-like circular electrode 1, the conical sheet-like electrode 201, and the sheet-like transition circular electrode 3 are all integrally formed with positioning parts. The inner wall of the ion channel of the mass spectrometer is provided with an assembly part that mates with the positioning part. The assembly part can be a bolt structure, and the positioning part can be a through hole; positioning is not achieved through a nut and bolt engagement. The positioning structure in the assembly part and the positioning part reduces the possibility of misalignment during assembly.

[0030] The positioning part can be a pin protruding from the outer diameter of the sheet-like circular electrode 1, the sheet-like transition circular electrode 3, and the conical sheet-like electrode 201. The assembly part is a slot opened on the inner wall of the ion channel. The pin and the slot engage to realize the rapid assembly of the electrode.

[0031] The positioning part does not affect the adjustment of the spacing, number, or diameter of the sheet-like circular electrodes 1, nor does it affect the layout of the voltage inputs of each electrode, thus ensuring both the flexibility of device adjustment and the stability of electric field application.

[0032] Among them, the sheet-shaped circular electrode 1, the sheet-shaped transition circular electrode 3, and the conical sheet electrode 201 are all made of conductive metal material (preferably stainless steel or titanium alloy), which has good conductivity, structural stability and corrosion resistance, ensuring the electric field stability and service life of the electrode.

[0033] The thickness of the sheet-like circular electrode 1 is 0.2mm-1mm, and the thickness of the conical sheet-like electrode 201 is 0.3mm-1.2mm, which reduces the space occupied by the electrodes for ion transport while ensuring structural strength.

[0034] In order to detect and trigger feedback of the delivery system, multiple high-resistivity ion current probes are radially and evenly installed at the end of the focusing section, the end of the collecting section, and the outlet of the ion delivery channel 101. The high-resistivity ion current probes penetrate deep into the inner wall of the channel and do not collide or interfere with the ion beam.

[0035] Example 2: like Figures 1 to 4 As shown, based on the mass spectrometry ion transport system, by adjusting the spacing between adjacent sheet-like circular electrodes 1, the number of sheet-like circular electrodes 1 within the same length, and the diameter of the sheet-like circular electrodes 1, in conjunction with the segmented gradient voltage application method of the gourd-shaped ion transport channel 101, and utilizing the segmented structure of the funnel-shaped converging electrode 2 to achieve gradient pressure along the process, a fine adaptation to the transport characteristics of ions with different mass-to-charge ratios can be achieved.

[0036] Therefore, a control method for a mass spectrometry ion delivery system is proposed. S1: Parameter matching based on the ion to be detected; Specifically, by coordinating the inner diameter of the inlet sheet-like circular electrode 1 of the focusing section and the initial applied voltage, a large-aperture, low-field-strength radial trapping electric field is constructed. This expands the effective ion trapping cross-section from φ3-φ5 mm in the traditional structure to φ6-φ8 mm, and increases the effective ion incident trapping angle from the conventional 15° to over 30°, significantly widening the ion entry range and reducing the initial loss caused by the incident angle shift. The inlet electrode voltage gradient is controlled at 1-3 V / mm to ensure low disturbance and wide coverage.

[0037] Among them, low-energy ion capture regulation: For low-energy, weakly ionized ions with a mass-to-charge ratio <500u and kinetic energy below 5 eV, the voltage gradient of the first three electrode groups in the focusing section is reduced to 0.5-2 V / mm. This reduces the forced deflection and rebound effect of the electric field on low-energy ions, preventing collisional annihilation of ions in the entrance region. Simultaneously, a gradually increasing voltage mode is employed to allow ions to smoothly enter the transport channel, improving the weakly ionized ion capture rate by over 30%.

[0038] Among them, high-energy ion capture regulation: For high-energy ions with ionization kinetic energy >20 eV, the field strength of the front-stage electrode in the focusing section is increased to 10-30 V / mm to construct a strong confinement and deceleration electric field. This rapidly confines and decelerates the high-energy ions radially, preventing them from directly penetrating the electrode gap and escaping. The first three stages of electrodes employ stepped voltage boosting to reduce the ion kinetic energy to below 5 eV within a 5 mm stroke, achieving stable capture of high-energy ions.

[0039] S2: Adjust the assembly according to the matched parameters; S3: Electric field loading and ion transport driven by segmented gradient voltage; Among them, through multiphysics simulation and extensive experimental fitting, the relationship between ion capture efficiency η and electrode voltage, electrode spacing and number of electrodes is established, so as to realize that parameter design is calculable, predictable and verifiable; η = η0 × 1 / (1 + e^(-k1×ΔU)) × 1 / (1 + e^(-k2×N / L)) × 1 / (1 +e^(k3×(D-D0))) The parameters in the formula are defined as follows: η: Total ion capture efficiency (0–1); η0: Ideal structure limit capture efficiency (0.95–0.99); ΔU: Total voltage rise from the inlet to the end of the focusing section (V); N / L: Number of electrodes per unit length (electrodes / cm); D: Electrode spacing (mm); D0: Optimal electrode spacing for mass-to-charge ratio ions (mm, determined by looking up a table of m / z). k1, k2, k3: Fitting coefficients (calibrated experimentally, k1≈0.02–0.05, k2≈0.3–0.8, k3≈1.2–3.0); Voltage term: 1 / [1+exp (-k1・ΔU)], the higher the voltage, the higher the capture efficiency, approaching saturation; Density term: 1 / [1+exp (-k2・N / L)], the denser the electrodes, the more stable the constraint and the higher the efficiency; Spacing term: 1 / [1+exp (k3・(D-D0))], the further the spacing deviates from D0, the faster the efficiency decreases; Among them, a simplified judgment formula is used for rapid on-site judgment; η≈C0 + C1・ΔU - C2・|D-D0| + C3・N / L; Where η: total ion capture efficiency (0–1); ΔU: total voltage rise from the inlet to the end of the focusing section (V); D: electrode spacing (mm); D0: optimal electrode spacing for mass-to-charge ratio ions (mm, determined by looking up a table from m / z); N / L: number of electrodes per unit length (electrodes / cm). C0 is the basic capture efficiency constant, which represents the basic efficiency value that the system can achieve under conditions of no voltage, no electrode density, and optimal spacing. C1 is the voltage term coefficient, which represents the degree to which the capture efficiency η improves for every 1V increase in the total voltage rise ΔU; C2 is the spacing deviation penalty (loss) coefficient. When the actual electrode spacing D deviates from the optimal spacing D0, the efficiency decreases by approximately 1 mm for every deviation. C3 is the electrode density gain coefficient; Suitable for rapid estimation in linear intervals, with an error of <8%.

[0040] Among them, the parameter threshold formulas for different mass-to-charge ratio ranges Small molecules (m / z < 500u): D0 = 0.1–0.3mm, N / L ≥ 8 molecules / cm, ΔU ≥ 50V Medium molecular weight (500≤m / z≤2000u): D0=0.3–1.0mm, N / L=4–8 particles / cm, ΔU=80–200V Macromolecules (m / z > 2000u): D0 = 1.0–2.0 mm, N / L ≤ 3 molecules / cm, ΔU ≥ 200V Where, when η≥0.9, the following condition is met: ΔU ≥ (1 / k1) × ln ( (η / η0) / (1 - η / η0) ); N / L ≥ (1 / k2) × ln ( (η / η0) / (1 - η / η0) ); |D - D0| ≤ (1 / k3) × ln ( (1 - η / η0) / (η / η0) ); S4: Controlling the radial direction of ions; Among them, radial constraint strength adjustment: By adjusting the electrode density in conjunction with the voltage gradient, the radial constraint field strength can be continuously adjusted from 0 to 500 V / cm.

[0041] For every increase of 1 electrode / cm, the radial field gradient decreases by 10%-15%, adapting to the confinement requirements of ion beams with different diameters. Small molecule ion beams are subject to moderate confinement of 50-150 V / cm, while large molecule ion beams are subject to strong confinement of 200-500 V / cm, ensuring that the ion beam maintains a stable beam waist radius throughout the transmission process.

[0042] The voltage offset of each sheet-like annular electrode 1 is corrected in real time by a programmable power supply, compensating for the coaxiality error of the electrode assembly and dynamically correcting the center trajectory of the ion beam.

[0043] The system acquires ion position signals every 10 ms and automatically adjusts the voltage difference between adjacent electrodes to ensure that the deviation between the ion beam center and the channel geometric axis is ≤0.01 mm, thus avoiding adsorption loss caused by the ion beam deviating from the tube wall.

[0044] For mixed mass-to-charge ratio ion systems, a segmented radial field strength differential setting is adopted: the field strength of the light ion segment is reduced by 20%-40% to avoid scattering caused by excessive confinement, while the field strength of the heavy ion segment is increased by 30%-60% to enhance the traction and confinement capabilities.

[0045] By matching radial field strength zones, space charge interference between ions with different mass-to-charge ratios is eliminated, enabling synchronous and stable focusing of multi-component ions.

[0046] By finely adjusting the slope of the four-segment voltage gradient, the average axial velocity of ions is precisely matched within the range of 10-200 m / s. Small molecular ions are transported at a high speed of 80-200 m / s to reduce diffusion loss, while large molecular ions are transported at a low speed of 10-60 m / s to ensure sufficient focusing.

[0047] For every 1 V / mm change in voltage gradient, the ion velocity can be stably adjusted by 5-15 m / s, with an adjustment linearity >98%.

[0048] To achieve precise and stable control of axial velocity within the range of 10-200 m / s, this embodiment does not rely on a single parameter, but rather employs a collaborative method of dynamic configuration of a four-segment voltage gradient slope and real-time calibration via a time-of-flight observation window, as specifically implemented below: The operator sets the target axial velocity according to the type of ion to be measured (e.g., 120 m / s for small molecules), and the system automatically converts the target velocity into the voltage gradient slope (V / mm) required for the four segments (focusing segment, sheet-like transition ring electrode, collection segment, and funnel-shaped closing electrode).

[0049] Based on extensive experimental fitting, the voltage gradient slope k (V / mm) and the average axial velocity of ions v (m / s) satisfy: v = α·k·√(z / m), where z is the charge number, m is the mass number, and α is the calibration coefficient related to the gas pressure in the channel and the electrode structure (preset before leaving the factory).

[0050] Focusing section: A gradually changing slope (e.g., 1-3 V / mm·cm) is used to smoothly accelerate ions from zero velocity (or low initial velocity) at the inlet, avoiding radial diffusion caused by sudden velocity changes; Transition electrode: Maintain a constant slope to ensure a smooth speed transition; Collection section: The slope is increased to a medium-high value (e.g., 5-15 V / mm·cm) to provide the axial driving force required for secondary focusing, while compressing the ion beam; Funnel-shaped converging electrode 2: The slope is further increased (e.g., 15-30 V / mm·cm), forming a "terminal sprint" effect, which enables ions to be injected into the mass analyzer at a precise target velocity.

[0051] To overcome the interference of factors such as ion quantity fluctuations and space charge effects on velocity, the system integrates a pair of grid electrodes (or uses two specific pieces from the existing sheet-like ring electrodes 1) at the inlet and outlet of the ion transport channel 101 to form a time-of-flight observation window.

[0052] Measurement steps: 1. A brief voltage pulse (pulse width ≤ 0.5 μs) is applied to the inlet grid electrode to generate a perturbation mark on the ion beam passing through at that moment.

[0053] 2. The outlet grid electrode continuously monitors the ion flow signal and records the time difference Δt when a marked ion cluster is detected passing through.

[0054] 3. Given the fixed distance L between the two grid electrodes (e.g., the entire collection section length), calculate the actual average axial velocity v. actual = L / Δt.

[0055] Closed-loop regulation: v actual With the preset target speed v target Compare and calculate the deviation Δv = v target - v actual If Δv > 0 (actual speed is too low), the system automatically increases the slope of the four voltage gradients by Δk (step size 0.2 V / mm·cm) synchronously to increase the driving force.

[0056] If Δv < 0 (actual speed is too high), then Δk is reduced synchronously. This adjustment is performed every 50 ms until |Δv| < 2 m / s, ensuring that the axial speed remains stable within ±2% of the preset value over a long period, and the measured linearity of the adjustment is >98%.

[0057] By optimizing the axial electric field distribution globally, the ion transport time from the inlet to the outlet can be set and repeated from 10 to 1000 μs.

[0058] The low field strength long delay mode (500-1000 μs) is suitable for high-precision focusing; the high field strength short delay mode (10-100 μs) is suitable for high-throughput rapid detection.

[0059] The transmission delay repeatability error is less than 3%, which meets the requirements for timing synchronization detection.

[0060] Based on the four-segment gradient voltage application, a real-time ion beam dispersion detection module and a voltage closed-loop feedback self-learning system are added to solve the problems of poor ion dispersion effect and inaccurate electric field matching.

[0061] Ion beam profile sensors are installed at three locations: the outlet of ion delivery channel 101, the end of the collection section, and the end of the focusing section. These sensors collect data in real time on four parameters: ion beam diameter, divergence angle, center offset, and density uniformity. When the ion beam dispersion exceeds a preset threshold (dispersion > 15%, beam waist diameter fluctuation > 0.2 mm), the system immediately triggers voltage feedback regulation.

[0062] To address the issue of how to specifically detect and provide feedback when "dispersion > 15% and waist diameter fluctuation > 0.2 mm", this embodiment designs a detection method based on a multi-position ion current probe array and a segmented, independent, and progressively optimized voltage feedback adjustment method.

[0063] At the three locations of the ion beam profile sensor—the end of the focusing section, the end of the collecting section, and the outlet of the ion delivery channel 101—a high-resistivity ion current probe array consisting of eight micron-sized (Φ0.1mm) tungsten needles is installed, uniformly distributed radially, with the needle tips penetrating approximately 0.5mm into the inner wall of the channel without colliding or interfering with the ion beam.

[0064] Real-time acquisition of 8-channel current signals: Dispersion S = (I max - I min ) / I max × 100%, threshold S>15% triggers adjustment; Among them, I max I is the maximum current. min Minimum current; Threshold S > 15% triggers regulation; Gaussian fitting was performed on the current distribution to obtain the beam waist diameter FWHM, and the standard deviation σ of 10 consecutive sets of data was calculated. D Adjustment is triggered when the diameter is > 0.2mm; FWHM ≈ 2.355 × W; W: Waist radius; σ D It is the standard deviation of 10 consecutive sets of FWHM data; if σ D > 0.2 mm indicates that the measurement results of the waist diameter have a large degree of dispersion, and the system stability or repeatability may be insufficient; Simultaneously, the center offset (deviation >10%) is determined by the ratio of the relative position probe currents, indicating electric field asymmetry or electrode assembly error. Density uniformity is determined by the coefficient of variation (CV) (CV < 10% indicates uniformity). Wherein, CV = (standard deviation of multi-probe current / mean current) × 100%.

[0065] When any metric exceeds the threshold, the system initiates a feedback process with a total time of less than 100ms: First, freeze the transition and funnel-shaped convergence electrodes, then slightly perturb (±2V) the voltage at the end of the focusing segment and the beginning of the collecting segment in sequence, and locate the problem segment by observing the changes in the dispersion of the three sensors. After positioning, the voltage gradient of the section is increased in steps of 1V / mm (keeping the input voltage constant), and S is recalculated after waiting 10ms for each step.

[0066] If S continues to decrease, continue until S < 10% or the cumulative adjustment exceeds 8V / mm. If S decreases first and then increases, back off one step to lock the optimal gradient.

[0067] For special cases: when over-focusing causes beam divergence (S is too high but the beam waist is too small), reduce the gradient of the preceding section by 0.5V / mm; when edge divergence is the main issue, increase the transition electrode voltage by 5-10V to strengthen the recovery electric field.

[0068] After adjustment, when the dispersion of the three sensors is stable within 10%, the waist fluctuation σ_D < 0.1 mm, and the center offset < 5%, the adjustment is stopped and the case is recorded for the system to learn from.

[0069] The feedback system aims to minimize dispersion by finely adjusting the voltage gradient segment by segment in the order of "focusing section → transition electrode → collection section → funnel-shaped closing electrode 2". If the dispersion is too high: gradually increase the voltage gradient of the corresponding segment to enhance the radial constraint, with an adjustment range of 0.5-2V / mm per step; If over-focusing causes beam divergence: gradually reduce the voltage gradient of the corresponding segment to weaken the constraint, with an adjustment range of 0.3-1V / mm per step; If edge dissipation is the main cause: increase the voltage difference between the transition electrode and the initial voltage of the collection section to strengthen the recovery electric field.

[0070] Among them, the self-learning output format generates a stable adaptive model for each type of ion: U opt = f (m / z, D, N, L, S) In the formula: U opt The optimal four-segment voltage sequence is defined as follows: m / z is the mass-to-charge ratio; D is the electrode spacing; N is the number of electrodes; L is the channel length; and S is the ion dispersion threshold.

[0071] The system executes differentiated adjustment strategies based on the combination characteristics of trigger conditions: When the dispersion S > 15% and the waist fluctuation σ D When the value is less than 0.1 mm, it is determined that the radial constraint is insufficient, and the voltage gradient of this segment is increased to enhance the constraint. When S>15% and σ D When the value is >0.2mm, it is determined that the ion beam has a "breathing" jitter effect. The voltage of the preceding section should be checked and stabilized first before fine-tuning this section. When S>15% and center offset>10%, it is determined that the assembly or electric field is asymmetrical, triggering an alarm to check the coaxiality of the electrodes and the consistency of the voltage on the left and right sides. When the density uniformity CV > 10%, it is determined that the ion beam is locally too dense. The gradient of this section should be appropriately reduced and the diameter expansion length of the preceding section should be increased.

[0072] By using a programmable power control system, voltage is applied to the independent voltage input of each electrode according to the above strategy, and the electric field distribution is monitored in real time to ensure that the electric field gradient changes gradually without abrupt changes in each segment. A uniform unidirectional electric field is formed in the conical output channel of the funnel-shaped converging electrode 2 along the conveying direction.

[0073] Based on the ions to be detected, parameter matching is performed. For small molecule ions, the electrode spacing is adjusted by selecting a 0.1mm ceramic insulating pad to reduce the electrode spacing and improve the sensitivity of the electric field response of small molecule ions.

[0074] Electrode quantity / density: The focusing section is designed to be 5cm long and has 50 sheet-like circular electrodes, with a density of 10 electrodes / cm; the collecting section is designed to be 3cm long and has 30 sheet-like circular electrodes, with a density of 10 electrodes / cm. The high density forms a gentle electric field gradient.

[0075] Electrode diameter: The inner diameter of the focusing section is slowly increased from 8mm to 12mm (2.5cm for the increasing section), and then slowly reduced to 6mm (2.5cm for the shrinking section), with a change rate of 0.8mm / cm; the inner diameter of the collecting section is slowly increased from 6mm to 8mm (1.5cm for the increasing section), and then slowly reduced to 4mm (1.5cm for the shrinking section), with a change rate of 0.67mm / cm. The slow diameter change avoids the escape of small molecule ions.

[0076] Funnel-shaped converging electrode 2: 6 conical sheet electrodes 201, spliced ​​together with a conical angle of 15°, the inner diameter of the output channel is reduced from 4mm to 2mm, precisely docking with the ion inlet (2mm) of the mass spectrometer mass analyzer.

[0077] Assemble the electrode assembly according to the above parameters, and assemble the sheet-like transition ring electrode 3 (6mm in diameter) using a positioning hole + positioning post structure. Fine-tune the coaxiality to an error of ≤0.02mm. Assemble the six conical sheet-like electrodes 201 into a funnel-shaped converging electrode 2 using a 0.08mm ultra-thin insulating pad, and assemble it at the ion outlet, ensuring that its coaxiality error with the sheet-like ring electrode 1 assembly is ≤0.02mm, and that the output channel is precisely connected to the end of the collection section.

[0078] The increased focusing section (2.5cm / 25 electrodes) uses a low-gradient voltage boost, from 0V to 50V, with a gradient of 2V per electrode; The focusing section's contraction segment (2.5cm / 25 electrodes) features a high-gradient voltage boost, from 50V to 100V, with a gradient of 2V per electrode; the overall electric field strength is 50V / cm. Transition electrode: A fixed voltage of 75V is applied separately (the average of 100V at the end of the focusing section and 50V at the beginning of the collecting section) to achieve a smooth transition of the electric field; In the enlarged section of the collection section (1.5cm / 15 electrodes), the voltage is increased by gradient, from 50V to 80V, with a gradient of 2V per electrode; The collecting section's contraction section (1.5cm / 15 electrodes) features an ultra-high gradient voltage boost, from 80V to 120V, with a gradient of 2.67V per electrode; the overall field strength is 80V / cm (1.6 times that of the focusing section). Funnel-shaped converging electrode 2: The voltage is increased at equal intervals along the ion transport direction. The initial voltage is matched with the end of the collection section at 120V. The following voltages are applied sequentially to the six conical sheet electrodes 201: 120V→126V→132V→138V→144V→150V. The voltage gradient between adjacent electrodes is 6V / electrode. The field strength at the end is 100V / cm (1.25 times that at the end of the collection section, which is within the range of 1.5-2.5 times). This forms a gentle unidirectional directional converging electric field to prevent the escape of small molecule ions.

[0079] To adapt to methanol ions (mass-to-charge ratio 150u) and perform multi-parameter coordinated adjustment, the insulating pad of the sheet-like circular electrode 1 was replaced with a 0.08mm pad, the focusing section was increased to 60 electrodes per 5cm, the collecting section was increased to 36 electrodes per 3cm, and the diameter change rate was reduced to 0.5mm / cm; the funnel-shaped converging electrode 2 was increased to 8 conical sheet electrodes 201, the ultra-thin insulating pad was replaced with a 0.05mm pad, and the cone angle was maintained at 15°; Voltage adjustment: The increasing segment of the focusing section is 0V→40V (gradient 1.33V / each), and the contraction segment of the focusing section is 40V→80V (gradient 1.33V / each); the transition electrode is 60V; the increasing segment of the collecting section is 40V→64V (gradient 1.6V / each), and the contraction segment of the collecting section is 64V→96V (gradient 2.13V / each); the funnel-shaped converging electrode 2 starts at 96V, and 96V→99V→102V→105V→108V→111V→114V→120V are applied sequentially to the 8 conical sheet electrodes 201, with a voltage gradient of 3V / each between adjacent electrodes, and a terminal field strength of 80V / cm, which is precisely matched to the characteristics of small molecule ions; After adjustment, the methanol ion capture efficiency reached 96.5%, and the transport efficiency reached 94.1%.

[0080] The embodiments disclosed herein are preferred embodiments, but are not limited thereto. Those skilled in the art can readily grasp the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A mass spectrometry ion delivery system, disposed within the ion channel of a mass spectrometer, the ion channel having an ion inlet and an ion outlet, comprising: Multiple coaxially arranged sheet-like annular electrodes are spliced ​​together to form an ion transport channel. The ion transport channel sequentially forms a focusing section and a collecting section along the ion transport direction. A sheet-like transition annular electrode connects the focusing section and the collecting section. A funnel-shaped converging electrode connected to the collecting section is provided at the ion outlet. The funnel-shaped converging electrode is characterized in that it is composed of multiple coaxially spliced ​​conical sheet-like electrodes, with a first ceramic insulating pad between adjacent conical sheet-like electrodes, and the whole assembly forms a conical output channel with an inner diameter that gradually narrows along the ion transport direction. Each sheet-like annular electrode, sheet-like transition annular electrode, and conical sheet-like electrode has an independent voltage inlet, and each voltage inlet is electrically connected to the control system of the mass spectrometer.

2. The mass spectrometry ion delivery system according to claim 1, characterized in that, The inner diameter of the transport channels in both the focusing and collecting sections increases first and then contracts along the ion transport direction, forming a two-stage gourd-shaped cavity structure.

3. The mass spectrometry ion delivery system according to claim 1, characterized in that, A second ceramic insulating pad is provided between adjacent sheet-like circular electrodes.

4. The mass spectrometry ion delivery system according to claim 1, characterized in that, Multiple tapered sheet electrodes are spliced ​​together to form an output channel, and the tapered angle of the output channel is 15°.

5. The mass spectrometry ion delivery system according to claim 1, characterized in that, Multiple high-resistivity ion current probes are radially and uniformly installed at three locations: the end of the focusing section, the end of the collecting section, and the outlet of the ion transport channel. The high-resistivity ion current probes penetrate deep into the inner wall of the channel and do not collide or interfere with the ion beam.

6. A control method for the mass spectrometry ion delivery system according to any one of claims 1 to 5, characterized in that, include: S1: Parameter matching based on the ion to be detected; S2: Adjust the assembly according to the matched parameters; S3: Electric field loading and ion transport driven by segmented gradient voltage; Among them, through multiphysics simulation and extensive experimental fitting, the relationship between ion capture efficiency η and electrode voltage, electrode spacing and number of electrodes is established, so as to realize that parameter design is calculable, predictable and verifiable. η = η0 × 1 / (1 + e^(-k1×ΔU)) × 1 / (1 + e^(-k2×N / L)) × 1 / (1 + e^(k3×(D-D0))); The parameters in the formula are defined as follows: η: total ion capture efficiency (0–1); η0: Ideal structure limiting capture efficiency (0.95–0.99); ΔU: Total voltage rise from the inlet to the end of the focusing section; N / L: Number of electrodes per unit length; D: Electrode spacing; D0: Optimal electrode spacing for mass-to-charge ratio ions; k1, k2, k3: Fitting coefficients (experimentally calibrated, k1≈0.02–0.05, k2≈0.3–0.8, k3≈1.2–3.0); Voltage term: 1 / [1+exp (-k1・ΔU)], the higher the voltage, the higher the capture efficiency, approaching saturation; Density term: 1 / [1+exp (-k2・N / L)], the denser the electrodes, the more stable the constraint and the higher the efficiency; Spacing term: 1 / [1+exp (k3・(D-D0))], the further the spacing deviates from D0, the faster the efficiency decreases; S4: Controls the radial direction of ions.

7. The control method for the mass spectrometry ion delivery system according to claim 6, characterized in that, include: Rapid on-site judgment is achieved through simplified judgment formulas; η≈C0 + C1・ΔU - C2・|D-D0| + C3・N / L; Where η: total ion capture efficiency (0–1); ΔU: total voltage rise from the inlet to the end of the focusing section; D: Electrode spacing; D0: Optimal electrode spacing for mass-to-charge ratio ions; N / L: Number of electrodes per unit length; C0 is the basic capture efficiency constant, which represents the basic efficiency value that the system can achieve under conditions of no voltage, no electrode density, and optimal spacing. C1 is the voltage term coefficient, which represents the degree to which the capture efficiency η improves for every 1V increase in the total voltage rise ΔU; C2 is the spacing deviation penalty coefficient. When the actual electrode spacing D deviates from the optimal spacing D0, the efficiency decreases by approximately 1 mm for every deviation. C3 is the electrode density gain coefficient, which represents the effect of changing the electrode density (N / L) on improving the capture efficiency. Suitable for rapid estimation in linear intervals, with an error of <8%.

8. The control method for the mass spectrometry ion delivery system according to claim 7, characterized in that, include: Acquire the current signal from the high-resistivity ion current probe: Dispersion S = (I max - I min ) / I max × 100%, threshold S>15% triggers adjustment; Among them, I max I is the maximum current. min Minimum current; Gaussian fitting was performed on the current distribution to obtain the beam waist diameter FWHM, and the standard deviation σ of 10 consecutive sets of data was calculated. D Adjustment is triggered when the diameter is > 0.2mm; FWHM ≈ 2.355 × W; W: Waist radius; σ D It is the standard deviation of 10 consecutive sets of FWHM data; if σ D > 0.2 mm indicates that the measurement results of the waist diameter have a large degree of dispersion, and the system stability or repeatability may be insufficient; Simultaneously, the center offset is determined by the ratio of the probe current to the relative position. A deviation of >10% indicates an asymmetric electric field or electrode assembly error. Density uniformity is determined by the coefficient of variation (CV); V < 10% indicates uniformity. Wherein, CV = (standard deviation of multi-probe current / mean current) × 100%.

9. The control method for the mass spectrometry ion delivery system according to claim 8, characterized in that, The system executes differentiated adjustment strategies based on the combination characteristics of trigger conditions: When the dispersion S > 15% and the waist fluctuation σ D When the value is less than 0.1 mm, it is determined that the radial constraint is insufficient, and the voltage gradient of this segment is increased to enhance the constraint. When S>15% and σ D When the value is >0.2mm, it is determined that the ion beam has a "breathing" jitter effect. The voltage of the preceding section should be checked and stabilized first before fine-tuning this section. When S>15% and center offset>10%, it is determined that the assembly or electric field is asymmetrical, triggering an alarm to check the coaxiality of the electrodes and the consistency of the voltage on the left and right sides. When the density uniformity CV > 10%, it is determined that the ion beam is locally too dense. The gradient of this section should be appropriately reduced and the diameter expansion length of the preceding section should be increased.

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