Ion current collection structure with high collection efficiency and mass spectrometer

Abstract

This invention relates to a high-efficiency ion current acquisition structure and a mass spectrometer. The ion current acquisition structure includes: a collection chamber adapted to be installed between the ion source and the sampling cone of the mass spectrometer; a trumpet-shaped aperture disposed within the collection chamber at the end facing the ion source; an annular electrode disposed on the inner wall of the trumpet-shaped aperture; and a beam rod assembly comprising multiple rod-shaped electrodes uniformly arranged circumferentially along the outlet of the trumpet-shaped aperture, with adjacent rod-shaped electrodes spaced apart to form gaps; wherein, on the side away from the ion source, the ends of the multiple rod-shaped electrodes are all bent and converged towards the central axis of the collection chamber. This invention provides a high-efficiency ion current acquisition structure that can improve the technical problems of low ion acquisition efficiency before entering the vacuum system and high background noise caused by the inability to effectively filter neutral particles in the prior art.

Description

Technical Field

[0001] This invention relates to the field of analytical instrument technology, and more particularly to mass spectrometry analysis technology. More specifically, this invention relates to a high-efficiency ion current acquisition structure and a mass spectrometer. Background Technology

[0002] Atmospheric pressure ionization mass spectrometry, such as inductively coupled plasma mass spectrometry (ICP-MS), electrospray ionization mass spectrometry (ESI-MS), and atmospheric pressure chemical ionization mass spectrometry (APC-MS), has become an indispensable analytical tool in fields such as chemistry, biology, medicine, and the environment. A common characteristic of these techniques is that the ionization process of the sample is completed in the ion source at atmospheric or near-atmospheric pressure, while the mass analysis and detection of the ions must be performed in the high-vacuum environment where the mass analyzer and detector are located. Therefore, an efficient and reliable interface must exist between the ion source and the mass analyzer to overcome the huge pressure gradient and successfully transport ions from the atmospheric pressure region to the high-vacuum region. The performance of this interface, especially its ion transport efficiency, directly determines the sensitivity, signal-to-noise ratio, and detection limit of the entire mass spectrometer.

[0003] Currently, the interface technologies commonly used in the industry mainly face the following challenges: Existing technical solution 1: The traditional "Sampling Cone - Skimmer Cone" structure. This is the most basic and classic interface design. Its working principle is to utilize the huge pressure difference across the sampling cone to drive a mixed gas flow containing ions, neutral solvent molecules, and background gas molecules through a tiny aperture (typically sub-millimeter) at the center of the sampling cone into the first-stage vacuum chamber. Ions are passively carried forward by the gas flow during this process. The main drawback of this solution is fundamental and primal: 1. Extremely low initial acquisition efficiency: The ion cloud generated by the ion source is inherently divergent in all directions. Traditional sampling cones can only receive ions within a very small solid angle range directly opposite the tiny aperture. The vast majority of ions deviating from the central axis are lost before reaching the sampling cone due to collisions, diffusion, or edge effects of the electric field, and never enter the vacuum system. This passive "waiting" acquisition method results in more than 99% of ions being wasted at the source, which is the most significant factor contributing to the loss of mass spectrometer sensitivity.

[0004] 2. Non-selective introduction and high background noise: The pressure-driven gas flow treats charged ions and uncharged neutral particles (such as N2, Ar, solvent vapor, and unionized matrix molecules) equally, indiscriminately drawing them into the vacuum system. These massive amounts of neutral particles not only significantly increase the pumping load on each stage of the vacuum pump, but more seriously, they will severely reduce the signal-to-noise ratio and detection limit of the analysis during subsequent ion transport and analysis by colliding with ions (leading to ion scattering loss), forming adduct ions (interfering with the qualitative and quantitative analysis of target analytes), or directly acting as chemical noise (increasing the background signal).

[0005] Existing technical solution two: Multipole ion guide technology within the vacuum stage. To overcome the shortcomings of traditional solutions, advanced mass spectrometers introduce radio frequency (RF) ion guides based on multipole ions (such as quadrupole, hexapole, octapole, etc.) in the first or subsequent vacuum chamber after the sampling cone. However, while this technical solution optimizes the ion transport process after entering the vacuum, its operational location means it still fails to solve the aforementioned fundamental problem: 1. The problem of inlet collection efficiency remains: This type of ion guide is located after the sampling cone, and it cannot change the huge ion loss caused by passive collection at the sampling cone inlet. It can only efficiently transport the few ions that "luckily" enter the vacuum system, but it is powerless to address the huge waste at the source.

[0006] 2. The problem of neutral particles has not been fundamentally solved: Neutral particles have also entered the vacuum system with the gas flow. Although the partially curved ion guide can separate ions and neutral particles by utilizing their different trajectories, this is a reactive measure. The neutral particles have already impacted the vacuum level of the first-stage vacuum chamber, and the separation process itself may not be thorough enough.

[0007] In summary, existing technologies still fail to provide an integrated solution that enables active, wide-range capture of ion streams, effective separation from neutral particles, and preliminary focusing of the ion beam at the atmospheric pressure end before ions enter the vacuum system of a mass spectrometer. Summary of the Invention

[0008] The purpose of this invention is to provide an ion flow acquisition structure with high acquisition efficiency, addressing the technical problems of low ion acquisition efficiency before entering the vacuum system and high background noise caused by the inability to effectively filter out neutral particles in the existing technology.

[0009] To achieve the above objectives, the core technical solution adopted by this invention is as follows: a high-efficiency ion current acquisition structure, comprising: A collection chamber, which is suitable for installation between the ion source and the sampling cone of a mass spectrometer; A funnel-shaped expansion aperture is located at the end of the collection chamber facing the ion source. An annular electrode is disposed on the inner wall of a funnel-shaped expanded aperture; and The beam rod assembly includes multiple rod-shaped electrodes, which are evenly arranged circumferentially along the horn-shaped aperture outlet, and adjacent rod-shaped electrodes are spaced apart to form gaps. On the side away from the ion source, the ends (52) of multiple rod-shaped electrodes all bend and converge toward the central axis of the collection chamber.

[0010] Furthermore, the beam assembly is connected to an radio frequency power supply.

[0011] Furthermore, the radio frequency power supply is used to apply radio frequency voltages with opposite phases to adjacent rod electrodes.

[0012] Furthermore, the ring electrode is connected to a DC power supply.

[0013] Furthermore, the DC power supply is used to apply a preset DC bias voltage between the ring electrode and the ion source.

[0014] Furthermore, the number of rod-shaped electrodes is 12 to 16.

[0015] Furthermore, the number of rod-shaped electrodes is 14.

[0016] Furthermore, the end of the rod-shaped electrode is configured to be smoothly bent toward the central axis.

[0017] Furthermore, the rod-shaped electrode is made of stainless steel or a conductive material with an inert metal plated on its surface.

[0018] Furthermore, a mass spectrometer is also provided, including the aforementioned high-efficiency ion flow acquisition structure.

[0019] Compared with the prior art, the beneficial effects of this invention are significant and multifaceted: 1. Significantly improved source acquisition efficiency and order-of-magnitude increase in sensitivity: This invention utilizes an active, wide-angle "electric field funnel" formed by a large-aperture funnel and annular electrodes to actively and extensively capture and guide the originally divergent ion cloud generated by the ion source towards the center. Compared to the passive reception of traditional sampling cones with tiny apertures, this approach fundamentally increases the number of ions captured at the source, providing an ion flux far exceeding existing technologies for subsequent analysis. This allows for an increase in the analytical sensitivity of the entire mass spectrometer by one or even several orders of magnitude.

[0020] 2. Achieving active solvent removal and noise reduction at the inlet, resulting in a significantly improved signal-to-noise ratio: This invention innovatively utilizes a spaced-out curved beam bar structure. This structure provides an "escape channel" for uncharged neutral particles (solvent molecules, background gas, matrix molecules, etc.) moving in a straight line, allowing them to be actively and efficiently separated and discharged as ions are confined by an electric field and travel along a curved path. This effectively prevents most noise sources from entering the subsequent vacuum system. This "source purification" mechanism greatly reduces the load on the vacuum system and chemical background noise, resulting in a significant improvement in the signal-to-noise ratio and detection limit of the analysis.

[0021] 3. Optimized ion beam quality for improved subsequent transmission efficiency: The structure of the beam rod end smoothly bending and converging towards the central axis achieves secondary focusing and collimation of the passing ion beam. It compresses the ion beam into a concentrated, highly directional ion stream with a smaller cross-section, allowing it to enter the sampling cone aperture in optimal shape and orientation. This not only reduces ion loss at the sampling cone entrance but also creates extremely favorable initial conditions for the efficient reception and transmission of ions by ion optics in the subsequent vacuum system.

[0022] 4. Integrated and modular design, easy to apply and upgrade: This invention cleverly integrates the three core functions of ion capture, neutral particle screening, and ion beam focusing into a compact, independent component located at the atmospheric pressure end. This modular design makes its installation, replacement, and maintenance extremely convenient. It can be easily applied to existing or new mass spectrometers as a "plug-and-play" upgrade component, making it highly practical in engineering applications. Attached Figure Description

[0023] To enable those skilled in the art to more clearly and comprehensively understand the technical solutions of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the accompanying drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings: Figure 1 This is a cross-sectional view illustrating the relative installation position of a high-efficiency ion current acquisition structure of the present invention in a mass spectrometer.

[0024] Figure 2 This is a three-dimensional structural diagram of the ion flow acquisition structure in a specific embodiment of the present invention.

[0025] Figure 3 yes Figure 2 A schematic diagram of the longitudinal section of the structure shown.

[0026] Figure 4 This is a trajectory diagram illustrating the working principle of the present invention, which vividly demonstrates the separation process of charged ions and neutral particles in this device using different trajectory lines.

[0027] In the above figures, the same reference numerals denote parts that have the same or similar functions. The names of the parts represented by each reference numeral are as follows: 100: High-efficiency ion current acquisition structure 10: Centralized Procurement Room 20: Horn-shaped enlarged hole 200: Ion source 300: Sampling cone 40: Ring electrode 50: Rod-shaped electrode 51: Gap 52: End 7: Ion trajectory 8: Trajectory of neutral particles. Detailed implementation method. The present invention will now be described in detail with reference to the accompanying drawings: To make the objectives, technical solutions, and advantages of this invention clearer, several preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described herein are merely for explaining the invention and do not constitute any limitation on its scope of protection. Any modifications, equivalent substitutions, or improvements made based on the spirit and principles of this invention should be included within the scope of protection of this invention.

[0028] Example 1 Please see Figures 1 to 4 This embodiment provides a high-efficiency ion flow acquisition structure 100. As a functionally independent and replaceable modular component, the core application scenario of this structure 100 is to be installed between the atmospheric pressure ionization ion source 200 of a mass spectrometer and the first-stage sampling cone 300 used to introduce ions into the vacuum system, i.e., to operate in an environment of atmospheric pressure or near-atmospheric pressure.

[0029] The high-efficiency ion current acquisition structure 100 of the present invention includes: a collection chamber 10, which is adapted to be installed between the ion source 200 and the sampling cone 300 of a mass spectrometer; a trumpet-shaped aperture 20 disposed at one end of the collection chamber 10 facing the ion source 200; an annular electrode 40 disposed on the inner wall of the trumpet-shaped aperture 20; and a set of beam rods 50, which includes multiple rod-shaped electrodes. The multiple rod-shaped electrodes are evenly arranged circumferentially along the outlet of the trumpet-shaped aperture 20, and adjacent rod-shaped electrodes are spaced apart to form gaps 51. On the side away from the ion source 200, the ends 52 of the multiple rod-shaped electrodes are all bent and converged towards the central axis of the collection chamber 10.

[0030] The collection chamber 10 serves as the structural base and environmental isolation cavity for all functional components of this invention. Its primary function is to provide a precise and stable mechanical platform, ensuring that the internal flared aperture 20, annular electrode 40, and a set of beam rods 50 can be accurately installed and positioned, achieving strict coaxial alignment with the external ion source 200 and sampling cone 300. Any misalignment will lead to electric field distortion and ion beam deflection, severely impacting transmission efficiency. Secondly, the cavity structure of the collection chamber 10 defines a relatively independent airflow region, helping to stabilize the airflow ejected from the ion source and providing a space for the separated neutral particles to collect and exit.

[0031] Structurally, the collection chamber 10 is typically designed as a roughly cylindrical or truncated conical metal or ceramic cavity open at both ends. The end facing the ion source 200 has a larger diameter to accommodate the flared orifice 20; the other end has a flange interface that matches the base of the sampling cone 300. This interface typically has an O-ring groove to form an airtight or near-airtight connection when docked with the sampling cone 300, preventing the intrusion of ambient air. Regarding material selection, considering the need to withstand certain temperatures (thermal radiation from the ion source) and chemical environments (solvent vapors), and the requirement for good electrical insulation and machinability, 304 or 316L stainless steel or aluminum alloy is preferred. Alternatively, machinable ceramics (such as alumina ceramics) can be used in applications requiring higher electrical insulation performance. Its inner walls typically require electropolishing or precision machining to reduce surface roughness and prevent charge accumulation and adsorption effects.

[0032] The funnel-shaped aperture 20 is the first-stage core structure for achieving large solid angle ion capture. Its working principle utilizes its geometry to significantly expand the effective receiving area of ​​the acquisition entrance. The ion cloud emitted from the ion source 200 exhibits an approximately Lambertian or Gaussian distribution in space, with a significant divergence angle. Traditional sampling cone apertures can only receive ions within a very small central angle. However, the funnel-shaped geometry of the funnel-shaped aperture 20 allows it to intercept and receive ions within a very large solid angle range, "catching" ions that would otherwise disperse to distant locations and guiding them into the subsequent electric field region.

[0033] Its geometric profile can be a simple linear conical surface, a smooth exponential curve, a hyperbola, or a complex freeform surface optimized by computational fluid dynamics (CFD) and ion trajectory simulation. A smooth surface profile, compared to a simple linear conical surface, is more conducive to creating a smooth airflow and electric field, reducing turbulence and ion loss near the wall. The diameter of its large-aperture end is typically designed to be on the order of several centimeters, for example, 1-3 centimeters, to match the ion cloud size of a typical atmospheric pressure ion source; the diameter of the small-aperture end matches the inscribed circle diameter of the inlet of the subsequent set of beam bars 50, typically 5-10 millimeters. It is usually integrally formed with the collection chamber 10, or precisely embedded as a separate component at the inlet end of the collection chamber 10.

[0034] The annular electrode 40 is a key component for achieving the first-stage active electrostatic pre-focusing. Its function is to apply a radial, centrally oriented constraint force as ions just enter the funnel-shaped aperture 20, thus initially converging the diverging ion beam. This is equivalent to adding an electrostatic lens at the collection entrance. It complements the geometric trapping effect of the funnel-shaped aperture 20, forming a dual trapping mechanism of "geometry + electric field," ensuring that a maximum number of ions can be effectively collected and guided to the subsequent beam rod region, rather than being lost on the inner wall of the funnel-shaped aperture due to excessive initial kinetic energy or collisions.

[0035] Structurally, it is a thin, conformally fitted metal ring to the inner wall of the flared aperture 20. It must maintain good electrical insulation from the wall of the flared aperture 20 (if the wall is conductive) or the cavity of the acquisition chamber 10 via an insulating component such as a high-temperature ceramic gasket or a sapphire ball. Its surface needs to be highly polished to prevent tip discharge. Its leads pass through a high-voltage vacuum insulator out of the wall of the acquisition chamber 10 and connect to an external DC power supply.

[0036] Beam rod assembly and rod electrode 50: This is a composite functional ion optical system that simultaneously undertakes three core tasks: radio frequency confinement transmission, neutral particle screening, and secondary focusing and collimation.

[0037] 1. Radio Frequency Confined Transmission: By applying radio frequency voltages with opposite phases to adjacent rod electrodes, a pseudopotential well is generated in the central region surrounded by the rod system. This potential well provides effective radial confinement for ions within a certain mass-to-charge ratio range, forcing the ions to travel stably only near the central axis, forming a controlled ion beam.

[0038] 2. Neutral particle screening: This is one of the key innovations of this invention. For example... Figure 4As shown, the charged ion trajectory 7 is forced to move along a curved channel under the combined influence of the radio frequency electric field and the curved geometry. Meanwhile, the uncharged neutral particle trajectory 8 is unaffected by the electric field and maintains approximately a straight line. They pass directly through the physical gap 51 between the rod-shaped electrodes, as if passing through a sieve, thus being effectively separated from the ion beam.

[0039] Each one is an independent, slender metal rod with a precise circular or hyperboloid cross-section. Hyperboloid cross-sections can generate the most ideal quadrupole field, but they are difficult to manufacture, and circular cross-sections are usually used as an approximation in engineering.

[0040] Arrangement: Multiple rod-shaped electrodes are evenly arranged along a virtual circumference with extremely high precision (typically better than 0.02 mm). They are fixed on a high-precision support made of insulating material (such as PEEK or ceramic) to ensure the long-term stability of their relative positions.

[0041] Gap 51: The physical distance between adjacent rod electrodes. A gap that is too small will hinder the effective expulsion of neutral particles; a gap that is too large will disrupt the integrity of the radio frequency field, creating field distortion at the gap and leading to a decrease in ion confinement capability or even ion loss. Typical gap sizes are between 0.5 and 1.5 mm.

[0042] The bending and contraction of the end 52 is the second key innovation for achieving secondary focusing and ion beam collimation. As the ion beam advances along the bent rod-shaped electrodes, the equipotential surface of the pseudopotential trap is compressed towards the center due to the contraction of the geometric boundaries. This process is gradual and smooth, in which the ions undergo an adiabatic compression process, effectively converting their radial kinetic energy into axial kinetic energy without causing heating or chaotic motion of the ion beam. Ultimately, at the exit, the originally wider ion beam is focused into a collimated ion stream with a smaller diameter, higher density, and better directionality. Further, this beam rod assembly can also act as a highly efficient ion lens, further optimizing ion beam quality through a collisional cooling mechanism. When all rod-shaped electrodes 50 are applied with the same or very close DC voltage (e.g., a positive voltage of +5V to +50V relative to the ion source to focus positive ions), its function transforms into that of a purely electrostatic ion focuser. In this operating mode, its main operating principle is as follows: Radial focused ion beam: The applied DC voltage creates a region of lowest potential (potential trap) near the central axis inside the beam. Ions entering this region experience an electrostatic force (Coulomb force) pointing towards the central axis, causing their trajectory to bend towards the axis.

[0043] Collision cooling or thermalization: As ions oscillate and advance within the potential trap, they undergo frequent low-energy collisions with residual background gas molecules (such as N2) within the device. These collisions effectively dissipate (or "cool") the radial kinetic energy of the ions, gradually reducing their oscillation amplitude and ultimately concentrating them strongly into a very small region near the central axis. The final effect of this process is that the initially dispersed ion beam with varying kinetic energies is transformed into a high-quality ion beam with a more concentrated spatial distribution and a narrower kinetic energy distribution that more closely approximates thermal velocity.

[0044] This process significantly reduces the radial dimension of the ion beam, improves the spatial density of the ion beam and subsequent transmission efficiency, and provides an ideal ion source for subsequent mass analysis, especially for time-of-flight mass spectrometers (TOF) which have demanding initial conditions.

[0045] A smooth curve is key to achieving efficient focusing and avoiding ion scattering, requiring the rod electrode to have extremely high continuity and precision in its fabrication process.

[0046] To achieve effective confinement and transport of ions, in a preferred embodiment of the present invention, a set of beam rods 50 are connected to a radio frequency (RF) power supply. More specifically, the RF power supply is used to apply RF voltages with opposite phases to adjacent rod electrodes.

[0047] This RF power supply is an electronic device capable of outputting a high-frequency (typically in the range of 0.5 MHz to 3 MHz) and high-voltage (peak-to-peak voltage Vp-p typically between 100V and 500V, or even higher) sine wave. Its output is split into two signals with exactly opposite phases (180° out of phase) by a center-tapped transformer or resonant circuit, each fed to two sets of staggered rod electrodes. For example, for 12 rod electrodes, electrodes numbered 1, 3, 5, 7, 9, and 11 are connected to the +Vrfsin(ωt) output, while electrodes numbered 2, 4, 6, 8, 10, and 12 are connected to the -Vrfsin(ωt) output. This alternating potential creates a rapidly changing saddle-shaped electric field at the center of the rod system. Although at any given instant the electric field is focused in one direction and divergent in another perpendicular direction, due to the rapid oscillation of the electric field, ions, due to their inertia, cannot follow the instantaneous electric field. Ultimately, they experience a time-averaged effective force pointing towards the center in all radial directions; this is the principle of the pseudopotential well. The depth of this potential well is proportional to (Vrf / ω). 2 And inversely proportional to the square of the radial distance, it can stably confine ions that satisfy the Matthew stability condition.

[0048] Preferably, in order to achieve preliminary ion capture and guidance, in a preferred embodiment of the present invention, the annular electrode 40 is connected to a DC power supply. More specifically, the DC power supply is used to apply a preset DC bias voltage between the annular electrode 40 and the ion source 200.

[0049] The DC power supply is a device capable of providing a stable, adjustable DC voltage (typically ranging from -300V to +300V). Its output is connected to the annular electrode 40. By applying a DC bias voltage relative to the ion source 200 (typically considered as ground potential or a reference potential) to the annular electrode 40, a stable electrostatic field can be established in the entrance region of the funnel-shaped aperture 20. For example, when analyzing positive ions, a negative DC bias voltage (e.g., -50V) is typically applied to the annular electrode 40. This negative potential attracts positive ions, forming a funnel-shaped electrostatic potential trap pointing towards the central axis. This potential trap acts as a "soft confinement," gently guiding ions with large divergence angles towards the center, unlike the strong repulsive barrier provided by a radio frequency field, thus "guiding" them into the receiving region of the subsequent set of beam bars 50. The magnitude of this DC bias voltage is adjustable and can be optimized according to different ion source types and gas flow conditions to achieve the best pre-focusing effect.

[0050] In a preferred embodiment, the number of rod electrodes is 12 to 16. This range is the result of a trade-off optimization between field quality, neutral particle removal efficiency, and engineering implementation difficulty. From the perspective of electric field quality, the higher the number of poles in a multipole, i.e., the more rod electrodes, the flatter the pseudopotential well formed in its central region, the wider the linear region, and the better the ion acceptance and transport quality. For example, a dodecole (12 rods) has a higher central field quality than an octole (8 rods). However, when the number of rods increases to a certain extent, such as exceeding 16, the marginal benefit of the improved field quality diminishes. From another perspective, the more rods there are, the smaller the gap 51 between adjacent rod electrodes becomes, with the total diameter remaining constant, which affects the neutral particle removal efficiency. In addition, a larger number of rods also means higher manufacturing and assembly precision requirements, as well as more complex drive circuitry. Therefore, 12 to 16 rods are considered an ideal engineering choice, providing a sufficiently high-quality RF field for efficient ion confinement, while retaining a sufficiently large gap for efficient neutral particle removal, while keeping manufacturing costs and difficulty within a controllable range.

[0051] In a preferred embodiment, the number of rod-shaped electrodes is 14. Further, the ends 52 of the rod-shaped electrodes are configured to be smoothly curved towards the central axis.

[0052] This means that the transition from the straight section to the curved section of the rod electrode, and the curvature change throughout the curved section, must be continuous, without any sharp inflection points or geometric abrupt changes. This is typically achieved through high-precision CNC machining or electrical discharge machining (EDM). The physical significance is that a smooth geometric boundary ensures that the equipotential surface of the RF pseudopotential well formed on it also changes smoothly. As the ion beam advances along this smoothly contracting channel, the radial compressive force it experiences gradually increases, and the entire focusing process is quasi-static and reversible. If there are uneven inflection points, the electric field will be distorted and abruptly changed at those points. Ions passing through will experience nonlinear scattering forces, similar to a high-speed car encountering a sharp turn, easily leading to "derailment" or chaos, resulting in increased ion energy (increased beam temperature) and transmission loss. Therefore, a smooth curved structure is the physical guarantee for achieving low-loss, high-quality secondary focusing.

[0053] In a preferred embodiment, the rod-shaped electrode is made of stainless steel or a conductive material with an inert metal coating.

[0054] The choice of materials directly affects the performance, lifespan, and applicability of the device.

[0055] Stainless steel (such as 304L or 316L): This is the most cost-effective option. It has good mechanical strength, corrosion resistance, and vacuum performance, and is easy to precision machine. For most common applications, stainless steel is perfectly adequate and reliable.

[0056] Conductive materials coated with inert metals: This is a higher-performance option. Typically, a layer of gold (Au) or rhodium (Rh) several micrometers thick is deposited onto a substrate such as stainless steel or oxygen-free copper through electroplating or physical vapor deposition (PVD). This approach offers three advantages: First, gold and rhodium have higher conductivity than stainless steel, reducing RF power loss at the electrode surface; second, they are chemically extremely stable noble metals with strong resistance to oxidation and corrosion, maintaining a smooth surface even in harsh chemical environments (such as analyzing strong acid samples) and preventing reaction with sample ions; third, the smooth inert metal surface reduces surface collisions and charge neutralization effects, further improving transmission efficiency. This option is particularly suitable for trace and ultra-trace analysis applications requiring extremely high sensitivity and stability.

[0057] In a preferred embodiment, the horn-shaped aperture 20, the annular electrode 40, and a set of beam rods 50 are fixed together in the collection chamber 10 to form an integral component.

[0058] This is a key feature of the engineering implementation and productization of this invention. It emphasizes the modular design concept of this device. During the manufacturing process, all core optical components, including the horn-shaped aperture, annular electrode, and beam rod, are pre-installed and fixed inside the collection chamber 10 on a high-precision assembly platform, forming an independent module where all internal relative positions are fixed and have passed offline testing. The advantages of this are significant: for mass spectrometer manufacturers, they can directly assemble this pre-calibrated module, greatly simplifying the assembly process and improving production efficiency and product consistency. For end users, when this component needs cleaning, maintenance, or upgrading, it can be easily disassembled from the instrument as a whole and quickly replaced with a new or cleaned spare module. The entire process may only take a few minutes, greatly reducing instrument downtime and improving instrument efficiency and maintainability. Example 2: To verify the actual effect of the high-collection-efficiency ion current collection structure 100 described in this invention, the following comparative experiment was conducted. The experiment employed inductively coupled plasma mass spectrometry (ICP-MS) to analyze standard solutions containing multiple elements under both conditions: without the device of this invention (i.e., using a conventional sampling cone-truncation cone structure) and with the device of this invention. Key performance indicators were compared. Test conditions (such as plasma power, gas flow, and detector voltage) remained consistent in both cases. The experimental results are shown in Table 1 below: Table 1: Performance Comparison Test Before and After Using the Device of This Invention The experimental data in Table 1 clearly show that: 1. The response value (representing sensitivity) is significantly improved: After installing the device of this invention, the response values ​​of all tested elements are greatly increased. For example, the response value of 55Mn increases from approximately 7.1 x 10⁻⁶. 5 cps / ppb increased to approximately 1.1x10 6 The increase in cps / ppb exceeds 50%. This directly demonstrates that the ion current acquisition structure of this invention greatly improves the overall ion transmission efficiency from the ion source to the detector.

[0059] 2. Effective reduction of background noise: Since the curved structure of the present invention effectively removes noise sources such as neutral particles, the background noise of most elements is significantly reduced.

[0060] 3. Significantly Improved Limit of Detection (Core Instrument Performance): Thanks to the combined effects of increased sensitivity and reduced noise, the instrument's ultimate analytical performance—the limit of detection (LOD)—has been significantly improved. For example, the LOD for 7Li decreased from 0.62 ng / L to 0.33 ng / L, and the LOD for 208Pb decreased from 0.83 ng / L to 0.68 ng / L. This indicates that the instrument can detect analytes at much lower concentrations, representing a qualitative leap in performance.

[0061] The experimental results demonstrate that, through its unique structural design, this invention successfully addresses the pain points of existing technologies in practice, achieving active and efficient ion capture at the inlet while effectively filtering noise, thereby comprehensively improving the core analytical performance of the mass spectrometer.

[0062] Example 3 This embodiment provides a mass spectrometer designed to achieve unprecedented high sensitivity and high signal-to-noise ratio analysis. According to claim 10, the mass spectrometer is characterized in that it includes the high-efficiency ion current acquisition structure 100 of any of the preceding embodiments.

[0063] The overall structure of the mass spectrometer, such as Figure 1 As shown, the system sequentially includes: an ion source 200 for converting sample molecules into gaseous ions at atmospheric pressure; followed by the core component of the invention—a high-efficiency ion flow acquisition structure 100; then a sampling cone 300 with a small aperture for introducing ions into the first-stage vacuum chamber; inside the vacuum system, subsequent ion optical systems such as radio frequency multipole or ion funnels for further ion transport and cooling, mass analyzers such as quadrupole mass analyzers, time-of-flight mass analyzers or orbital trap mass analyzers, and an ion detector such as an electron multiplier are arranged sequentially.

[0064] Workflow and Synergistic Effects: In the overall workflow of the mass spectrometer, the high-efficiency ion flow acquisition structure 100 of this invention plays a crucial role.

[0065] 3. Highly efficient entry: Ions generated by ion source 200 are first efficiently captured by structure 100, ensuring that the number of ions entering the subsequent system is much greater than that of existing technologies.

[0066] 4. Source "security check": During transmission, neutral noise particles are actively separated and removed, ensuring that the airflow entering the vacuum system is a "pure" ion flow, fundamentally purifying the analytical environment.

[0067] 5. Optimize the "formation": Before leaving structure 100, the ion beam is focused into a high-quality collimated ion stream to pass through the "narrow gate" of sampling cone 300 in the best possible condition.

[0068] Overall Performance Improvement: Due to the revolutionary improvements brought about by Structure 100 at the source, the performance of the entire mass spectrometer is comprehensively enhanced. Higher ion flux directly translates into higher signal intensity and analytical sensitivity; lower background noise directly translates into a higher signal-to-noise ratio and a lower detection limit; and optimized ion beam initial conditions also result in higher efficiency and less transmission loss for all subsequent ion optics. Therefore, a mass spectrometer equipped with Structure 100 of this invention can exhibit superior performance far exceeding existing technologies when analyzing trace or ultra-trace targets in complex matrix samples.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency ion current collection structure (100), characterized in that, include: A collection chamber (10) is installed between the ion source (200) and the sampling cone (300) of the mass spectrometer; A funnel-shaped expansion hole (20) is disposed at one end of the collection chamber (10) facing the ion source (200); An annular electrode (40) is disposed on the inner wall of the flared aperture (20); and The beam rod assembly includes multiple rod-shaped electrodes (50), which are evenly arranged circumferentially along the outlet of the horn-shaped aperture (20), and adjacent rod-shaped electrodes (50) are spaced apart to form a gap (51). In particular, on the side away from the ion source (200), the ends (52) of the multiple rod-shaped electrodes all bend and converge toward the central axis of the collection chamber (10).

2. The high-efficiency ion current acquisition structure (100) according to claim 1, characterized in that, The beam arm assembly is connected to an radio frequency power supply.

3. The high-efficiency ion current acquisition structure (100) according to claim 2, characterized in that, The radio frequency power supply is used to apply radio frequency voltages with opposite phase to adjacent rod electrodes.

4. The high-efficiency ion current acquisition structure (100) according to claim 1, characterized in that, The annular electrode (40) is connected to a DC power supply.

5. The high-efficiency ion current acquisition structure (100) according to claim 4, characterized in that, The DC power supply is used to apply a preset DC bias voltage between the ring electrode (40) and the ion source (200).

6. The high-efficiency ion current acquisition structure (100) according to claim 1, characterized in that, The number of rod-shaped electrodes (50) is 12 to 16.

7. The high-efficiency ion current acquisition structure (100) according to claim 6, characterized in that, The number of rod-shaped electrodes (50) is 14.

8. The high-efficiency ion current acquisition structure (100) according to claim 1, characterized in that, The end (52) of the rod electrode (50) is configured to be smoothly bent toward the central axis.

9. The high-efficiency ion current acquisition structure (100) according to claim 1, characterized in that, The rod-shaped electrode is made of stainless steel or a conductive material with an inert metal coating.

10. A mass spectrometer, characterized in that, Includes the high-efficiency ion flow acquisition structure (100) according to any one of claims 1 to 9.

Images