Double-layer shielded ion transfer tube with in-situ nondestructive observation

Abstract

This invention relates to the field of ion migration technology and discloses a double-shielded ion migration tube for in-situ non-destructive observation. The ion migration tube includes an inner migration tube and an outer shielding tube. The inner migration tube includes multiple inner migration rings and multiple resistors; the inner migration rings are spaced apart along a first direction to form a migration cavity with an inner observation window; adjacent inner migration rings are connected by resistors to form a gradient electric field within the migration cavity with a gradually decreasing potential along the first direction. This gradient electric field drives ions entering the migration cavity to move along the first direction. The outer shielding tube is located outside the inner migration tube and forms a shielding gap with it; an outer observation window is formed on the wall of the outer shielding tube, corresponding to the inner observation window. This double-shielded ion migration tube for in-situ non-destructive observation enables accurate measurement of the actual ion migration behavior and non-destructive acquisition of ion mobility.

Description

Technical Field

[0001] This invention relates to the field of ion migration technology, and in particular to a double-shielded ion migration tube that allows for in-situ non-destructive observation. Background Technology

[0002] Accurate characterization of gas-phase ion transport properties is fundamental to improving the performance of ion mobility analysis. The actual ion movement behavior in a migration tube—including ion swarm diffusion, mobility distribution, and space charge effects—directly determines detection resolution, sensitivity, and the accuracy of mobility measurements. However, current research on these behaviors primarily relies on numerical simulations such as SIMION and COMSOL. Because simulations require assumptions such as ideal electric fields, neglecting space charge effects, and simplifying inter-ion interactions, systematic deviations exist between simulation results and actual ion behavior, making it difficult to completely replace direct experimental observation of real migration behavior. Therefore, achieving in-situ, non-destructive observation of ion movement within a migration tube is of significant research value.

[0003] like Figure 1 and Figure 2 As shown, ion migration tubes currently commonly employ a single-layer closed-loop stacked structure, consisting of multiple metal ring electrodes arranged axially at intervals and connected in series by resistors to create a gradient electric field within the tube, driving the directional migration of ions. This closed structure maintains the axial uniformity of the electric field through the continuous tube wall and isolates external electromagnetic interference through the shielding effect of the metal rings. It offers advantages such as compact structure and low power consumption in the design of portable and miniaturized instruments.

[0004] However, existing single-layer closed structures have inherent technical contradictions: to achieve in-situ observation of ion movement within the tube, observation windows must be opened in the tube wall; however, directly opening the window will cut off the electric field lines, leading to severe edge electric field distortion and disrupting the uniform electric field environment required for ion migration. Simultaneously, opening the window exposes the migration cavity directly to the external electromagnetic environment, and the penetration of the external electric field will interfere with the normal migration trajectory of ions, resulting in significant errors in mobility measurements. Attempting to reduce the tube diameter to accommodate the limited optical observation angle can reduce the radial diffusion blind zone, but it sacrifices ion transport efficiency and separation performance. Conversely, if the window area is increased to ensure a sufficient observation field, electric field distortion and external interference will be further exacerbated, making it impossible to guarantee the controllability and repeatability of ion migration conditions.

[0005] Therefore, existing single-layer structures cannot simultaneously meet the requirements of interference-free ion detection and high-performance migration condition control. On the one hand, the closed structure hinders direct observation of the actual ion migration behavior, forcing researchers to rely on indirect measurements or numerical simulations at the exit end, making it difficult to capture key physical phenomena such as dynamic diffusion and space charge effects during ion migration. On the other hand, if an observation window is directly introduced into the single-layer structure, it must be at the expense of electric field uniformity and electromagnetic shielding, leading to distorted measurement results. This structural contradiction between observational accessibility and electric field integrity has become a key bottleneck restricting fundamental research on ion migration and the improvement of instrument performance.

[0006] There is an urgent need for a novel ion migration tube structure that can achieve in-situ, non-destructive direct observation of ion movement within the migration cavity while maintaining a highly uniform axial electric field and effective electromagnetic shielding. This would allow for the establishment of a realistic physical model of ion transport and the accurate, non-destructive acquisition of ion mobility. Summary of the Invention

[0007] This invention provides an ion migration tube with double-layer shielding for in-situ, non-destructive observation. The ion migration tube of this invention enables precise measurement of the actual migration behavior of ions and non-destructive acquisition of ion mobility.

[0008] This invention provides an ion migration tube with double-layer shielding that allows for in-situ non-destructive observation, comprising an inner migration tube and an outer shielding tube; The inner migration tube includes multiple inner migration rings and multiple resistors; the multiple inner migration rings are arranged at intervals along a first direction to form a migration cavity with an inner observation window; two adjacent inner migration rings are connected by the resistors to form a gradient electric field in the migration cavity with a potential that gradually decreases along the first direction, and the gradient electric field is used to drive ions entering the migration cavity to move along the first direction. The outer shielding tube is sleeved on the outside of the inner migration tube and forms a shielding gap with the inner migration tube. The outer shielding tube is used to provide electromagnetic shielding. An external observation window is opened on the tube wall of the outer shielding tube, and the external observation window is correspondingly set with the inner observation window.

[0009] According to the present invention, the double-shielded ion migration tube for in-situ non-destructive observation has a standard region inside the migration cavity, and the cross-section of the standard region is a circle with a diameter of not less than 15 mm.

[0010] The double-layer shielded ion migration tube for in-situ non-destructive observation provided by the present invention includes an inner migration ring comprising: The arc segment is a semi-circular arc; Two straight line segments are arranged parallel to each other and spaced apart; the two ends of the arc segment extend along the tangent direction to form two straight line segments respectively, and the interval between the two straight line segments forms the inner observation window.

[0011] According to the double-layer shielded ion migration tube provided by the present invention, the inner diameter of the semi-circular arc is... Not less than 25 millimeters.

[0012] The length of the straight segment in the double-shielded ion migration tube for in-situ non-destructive observation provided by the present invention is... Not less than 70 mm.

[0013] The ion migration tube with double-layer shielding for in-situ non-destructive observation provided by the present invention, the spacing between two adjacent inner migration rings It ranges from 1 mm to 5 mm.

[0014] According to the double-layer shielded ion migration tube provided by the present invention, the thickness of the inner migration ring is... It ranges from 0.5 mm to 1 mm.

[0015] The double-layer shielded ion migration tube for in-situ non-destructive observation provided by the present invention further includes: An environmental control box, in which both the inner migration tube and the outer shielding tube are placed.

[0016] The double-layer shielded ion migration tube for in-situ non-destructive observation provided by the present invention further includes: An insulating connector is disposed in the shielding gap, and both ends of the insulating connector are respectively connected to the inner migration ring and the outer shielding tube.

[0017] This invention provides a double-shielded ion migration tube for in-situ non-destructive observation. The design, with an inner observation window on the inner migration tube and an outer observation window on the outer shielding tube, allows external detection equipment to directly observe ion movement within the migration cavity without disrupting the electric field or ion flow, thus achieving in-situ, non-destructive measurement of ion migration behavior. By placing a resistor between two adjacent inner migration rings, a gradient electric field with a gradually decreasing potential along a first direction (axial direction) can be configured within the migration cavity, ensuring that ions entering the migration cavity can migrate under the influence of this gradient electric field. Furthermore, by adjusting the resistance value or input voltage, the potential difference between two adjacent inner migration rings can be controlled, thereby generating a highly uniform axial electric field within the migration cavity. A uniform electric field is crucial for accurate ion mobility measurement, preventing deviations in ion trajectories due to electric field distortion. By selecting different resistor values, the electric field intensity distribution can be customized to suit the study of different ion migration characteristics. This invention not only resolves the contradiction between the inability of traditional migration tubes to simultaneously achieve electric field uniformity and non-destructive observation but also provides a controllable experimental platform for studying complex ion behavior. By adjusting the electric field strength and combining it with the ion movement time or trajectory recorded at the observation port, the true ion mobility can be directly calculated, avoiding the errors introduced by indirect measurement in traditional methods. The outer shielding tube, acting as a shielding layer, combined with the shielding gap, can shield the external electric field from the migration cavity, further improving measurement accuracy. In summary, the double-shielded, in-situ, non-destructive ion migration tube of this invention enables precise measurement of the true ion migration behavior and non-destructive acquisition of ion mobility. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of an existing ion migration tube.

[0020] Figure 2 yes Figure 1 The diagram shows the main structure of the ion migration tube.

[0021] Figure 3 This is a schematic diagram of the assembly structure of the inner migration tube and the outer shielding tube of the double-layer shielded ion migration tube that can be observed in situ without damage, provided by the present invention.

[0022] Figure 4 yes Figure 3 The diagram shown is a left-side view of the ion migration tube, which is double-shielded and can be observed in situ without damage.

[0023] Figure 5 This is a three-dimensional structural diagram of the inner migration tube of the double-layer shielded ion migration tube that can be observed in situ without damage, provided by the present invention.

[0024] Figure 6 yes Figure 5 The diagram shows the main view of the inner migration tube structure.

[0025] Figure 7 The process of ion cluster width change in COMSOL simulation; (a) Schematic diagram of simulation model structure; (b) Concentration change during simulated ion flow transport; (c) Electric field distribution between high-voltage and low-voltage plates; (d) Ion concentration on the starting and ending position lines.

[0026] Figure 8 The effect of the inner diameter of the inner migration ring on the uniformity of the electric field in COMSOL simulation. (a) Schematic diagram of the simulation model structure; (b) Distribution of equipotential lines in the inner migration ring; (c) Variation of electric field intensity in the x-direction at the edge of the standard region; (d) Relationship between the variation of the inner diameter of the inner migration ring and the deviation of the electric field intensity in logarithmic coordinates.

[0027] Figure 9 The simulation results show the relationship between the length of the straight line segment and the relative error rate of the potential. (a) The structure and electric field distribution of the parallel electrode strip replacing the semicircular ring; (b) The relationship between the length change of the parallel electrode strip and the potential error rate of the plate in logarithmic coordinates; where the parallel electrode strip is two straight line segments of the inner migration ring.

[0028] Figure 10 A comparison of COMSOL products with and without an outer shielding tube.

[0029] Figure 11 This is a schematic diagram illustrating the principle of ion movement within an ion migration tube that can be observed in situ without damage, thanks to the double-layer shielding provided by this invention.

[0030] Figure label: 110. Inner migration tube; 111. Inner migration ring; 112. Migration cavity; 120. Outer shielding tube; 130. Shielding gap. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0033] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0035] In embodiments of the present invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0036] like Figure 1 and Figure 2As shown, existing migration tubes generally employ a single-layer, fully enclosed, stacked ring structure. While this offers certain advantages in portable, miniaturized instrument design, its limitations become increasingly apparent when faced with the demands for a balance between electric field uniformity, potential shielding, and observation window. Reducing the size of the migration tube helps decrease volume and energy consumption, but sacrifices ion transport efficiency and separation performance; enlarging the opening for observation, however, easily introduces electric field distortion and external interference, affecting the accuracy of experimental results. Therefore, the existing migration tube structure cannot simultaneously meet the requirements of interference-free ion detection and high-performance migration condition control.

[0037] The following is combined Figures 3 to 11 The present invention describes the double-shielded ion migration tube that enables in-situ non-destructive observation.

[0038] like Figures 3 to 6 As shown, a specific embodiment of the present invention provides an ion migration tube with double-layer shielding for in-situ non-destructive observation. This double-layer shielding ion migration tube includes an inner migration tube 110 and an outer shielding tube 120.

[0039] The inner migration tube 110 includes multiple inner migration rings 111 and multiple resistors; the multiple inner migration rings 111 are arranged at intervals along a first direction to form a migration cavity 112 with an inner observation window; two adjacent inner migration rings 111 are connected by resistors to form a gradient electric field in the migration cavity 112 with a gradually decreasing potential along the first direction, and the gradient electric field is used to drive ions entering the migration cavity 112 to move along the first direction.

[0040] The outer shielding tube 120 is sleeved on the outside of the inner migration tube 110, and a shielding gap 130 is formed between them. The outer shielding tube 120 is used to provide electromagnetic shielding. An external observation window is provided on the tube wall of the outer shielding tube 120, and the external observation window is set in correspondence with the internal observation window.

[0041] It should be noted that the first direction is the ion transport direction, which is also the axial direction of the inner migration tube 110 and the outer shielding tube 120. In other words, ions are transported along the axial direction of the inner migration tube 110 and the outer shielding tube 120.

[0042] In this embodiment, the design of an inner observation window on the inner migration tube 110 and an outer observation window on the outer shielding tube 120 allows external detection equipment to directly observe the ion movement in the migration cavity 112 without disrupting the electric field or ion flow, thus achieving in-situ, non-destructive measurement of ion migration behavior. By setting a resistor between two adjacent inner migration rings 111, a gradient electric field with a gradually decreasing potential along the first direction can be configured in the migration cavity 112, ensuring that ions entering the migration cavity 112 can migrate under the influence of this gradient electric field. Furthermore, the potential difference between two adjacent inner migration rings 111 can be controlled by adjusting the resistance value or the input voltage, thereby generating a uniform axial electric field within the migration cavity 112. A uniform electric field is crucial for accurate ion mobility measurement, preventing ion trajectory deviations from expectations due to electric field distortion. By selecting resistors with different resistance values, the electric field intensity distribution can be customized to suit the study of migration characteristics of different ions. This embodiment not only resolves the contradiction between the inability of traditional closed-loop migration tubes to simultaneously achieve electric field uniformity and non-destructive observation, but also provides an adjustable experimental platform for studying complex ion behavior. By adjusting the electric field strength and combining it with the ion movement time or trajectory recorded at the observation port, the true ion mobility can be directly calculated, avoiding the errors introduced by indirect measurement in traditional methods. The outer shielding tube 120, acting as a shielding layer, combined with the shielding gap 130, can shield the influence of the external electric field on the migration cavity 112, further improving measurement accuracy. The double-layer shielded ion migration tube of this embodiment, capable of in-situ non-destructive observation, enables precise measurement of the true ion migration behavior and non-destructive acquisition of ion mobility.

[0043] Optionally, the number of internal observation windows is at least one. When there are multiple internal observation windows, they can be arranged along the first direction or around the first direction.

[0044] Preferably, the number of external observation windows is equal to the number of internal observation windows, and the external observation windows are set in a one-to-one correspondence with the internal observation windows.

[0045] Optionally, the inner migration ring 111 may be made of at least one material selected from stainless steel, gold, silver, aluminum, and copper. Preferably, the inner migration ring 111 is made of 316L stainless steel.

[0046] Optionally, the outer shielding tube 120 can be made of plastic. The cross-section of the outer shielding tube 120 is U-shaped. That is, the outer shielding tube 120 can be a plastic U-shaped plate.

[0047] It should be noted that, if the dimension along the first direction is defined as length, in some embodiments, the length of the inner observation window can be less than the length of the inner migration tube 110. That is, the inner observation window may not penetrate the inner migration tube 110 in the first direction. In other embodiments, the length of the inner observation window is equal to the length of the inner migration tube 110. That is, the inner observation window penetrates the inner migration tube 110 in the first direction, such as... Figure 3 and Figure 5 As shown.

[0048] In some embodiments of the present invention, the double-shielded ion migration tube for in-situ non-destructive observation further includes an insulating connector; the insulating connector is disposed in the shielding gap 130, and both ends of the insulating connector are respectively connected to the inner migration ring 111 and the outer shielding tube 120.

[0049] In this embodiment, the insulating connector serves to fix the inner migration tube 110 and the outer shielding tube 120 in the shielding gap 130, and can also ensure electrical isolation between the inner migration tube 110 and the outer shielding tube 120, avoid electric field interference, and maintain the stability of the electric field inside the inner migration tube 110.

[0050] Optionally, the insulating connector can be a plastic connecting rod. The two ends of the connecting rod are connected to the inner migration ring 111 and the outer shielding tube 120, respectively.

[0051] In some embodiments of the present invention, the migration cavity 112 has a standard region with a circular cross-section. The diameter of the circle is configured to ensure that the electric field uniformity within the standard region is sufficient for accurate measurement of ion mobility. Optionally, the cross-section of the standard region is a circle with a diameter of not less than 15 mm.

[0052] Because ion transport along the axial direction (i.e., the first direction) is accompanied by radial divergence, the design parameters of the inner diameter of the standard region need to allow sufficient space to avoid the ion cluster being affected by the limited radial area, thus preventing the ion cluster from being affected by the limited radial area. In this embodiment, the cross-section of the standard region is designed as a circle with a diameter of not less than 15 mm, which can prevent the ion cluster from being affected by the limited radial area, thus preventing the ion cluster from being affected by the limited radial area.

[0053] The design process for the standard area is as follows: The standard region refers to the area within the migration tube where the electric field performance meets the design standards for uniformity and shielding, including the ion transport distance and cross-section. According to relevant literature, the length of the migration region in a migration tube under ambient pressure is generally 40 mm to 200 mm. In the simple environment set up in the preliminary experiments, a migration distance of 70 mm was sufficient to observe the divergent transport of ions; therefore, the distance did not need to be too long, and 200 mm was initially selected. Because ion transport along the axial direction is accompanied by radial divergence, the design parameters of the inner diameter of the standard region need to have sufficient space to avoid the ion cluster being constrained by the radial area. The initial area of ​​the ion cluster is determined by a pre-set mask, which is a thin metal sheet with a central cutout, equivalent to the aperture of the ion flow. Considering the shape of the spray plume of the electrospray ionization source, the size of the laser spot, and the camera's imaging area, the initial cross-section of the ion cluster is set to a circle with a diameter of 3 mm. Previous studies estimated the size of the ion swarm termination cross section passing through the migration tube using COMSOL simulation software. In a uniform electric field of 50 V / mm generated by infinitely large parallel plates, an ion current of 1 nA continuously flows in from the center position, with an ion diffusion coefficient of 3.10. -6 m 2 / s, taking into account the combined effects of diffusion and space charge density coupling, the resulting ion transport results are as follows: Figure 7 As shown, the width of the ion cluster at the termination position is 13.35 mm. Considering the actual situation, the ion current is even smaller and it flows in in the form of pulses. Setting the cross-sectional diameter of the standard area to be no less than 15 mm in a circle can meet the requirements.

[0054] Traditional migration tubes typically employ a single-layer, fully enclosed, stacked ring structure. To enable external observation, observation windows must be created in the tube wall, forming a semi-open structure. However, once a window is opened in the single-layer structure, the continuous shielding of the tube wall against external stray electric fields is disrupted. External interference potentials will directly affect the uniformity of the electric field within the migration cavity through the opening, causing ion trajectories to deviate from expectations and resulting in distorted observation results. This contradiction indicates that a single-layer structure alone cannot simultaneously meet the requirements of both windowed observation and electric field shielding. Therefore, an independent outer shielding structure is needed to decouple the observation and shielding functions, with the inner and outer layers handling these functions respectively.

[0055] However, even with a double-layer structure, where the outer layer is dedicated to shielding, the migration cavity still faces lateral electric field distortion at the window location of the inner migration tube. Due to the lack of a continuous conductor constraining the window edge, the equipotential surface bends near the window, causing local electric field inhomogeneity and affecting ion migration behavior within the standard region. Therefore, simply truncating the window is insufficient; a targeted design of the electrode structure at the window edge is necessary. By appropriately extending the electrodes on both sides of the window, the edge electric field distortion can be compensated, thereby maintaining a high degree of electric field uniformity within the standard region while preserving the observation window.

[0056] like Figures 4 to 6 As shown, in some embodiments of the present invention, the inner migration ring 111 includes an arc segment and two straight segments. The arc segment is a semi-circular arc. The two straight segments are arranged parallel to each other and spaced apart. The two ends of the arc segment extend tangentially to form two straight segments, and the gap between the two straight segments forms an inner observation window. In other words, the two straight segments are formed by the two ends of the arc segment extending outward tangentially and are arranged parallel to each other to constitute the inner observation window; the straight segments are equivalent to parallel electrode strips. That is, the inner migration ring 111 forms a U-shaped cross-section structure, and its two straight segments are equivalent to two parallel electrode strips. This ensures that the electric field in the standard region is consistent with the unwindowed portion, reduces the relative potential error, and maintains the continuity of the electric field shielding at the inner observation window.

[0057] For example, the inner migration ring 111 can be formed by bending a single electrode into a U-shape, which is equivalent to cutting a ring electrode in half and then extending the left and right ends to form an electrode strip that is parallel to the top and bottom.

[0058] like Figure 4 As shown, optionally, the inner diameter of the semicircular arc is adapted to the inner diameter of the outer shielding tube 120 to form a reasonable electric field distribution between the migration cavity 112 and the shielding gap 130. Specifically, the arc segment is a semicircular arc, and the inner diameter of the semicircular arc... Not less than 25 mm. Preferably, the inner diameter of the semicircular arc. It can be 25 mm, 35 mm, or 45 mm.

[0059] Optional, length of the line segment It is configured to extend the electric field shielding to the vicinity of the outer shielding tube 120 to maintain the shielding at the inner observation window; specifically, the length of the straight segment... All should be no less than 70 millimeters. Preferably, the length of the straight segment... It can be 70 mm, 80 mm, or 100 mm.

[0060] Optional, the thickness of the inner migration ring The thickness is 0.5 mm to 1 mm. Preferably, the thickness of the inner migration ring is... It can be 0.5 mm, 0.8 mm, or 1 mm.

[0061] Design process of inner migration ring 111 in this embodiment of the invention: The main function of the inner migration ring 111 is to create a uniform electric field environment, and space needs to be reserved for the excitation light to pass through between the rings (i.e., the migration cavity). Its main design parameters are spacing, material, thickness, and inner diameter. Considering the diameter of the migration tube and the shooting area of ​​the camera, a spacing of 5 mm is selected. The thinner the inner migration ring 111, the better for the uniformity of the electric field. However, an excessively thin inner migration ring 111 is prone to deformation, which will produce large assembly errors. Taking all factors into consideration, a thickness of 0.5 mm is selected, and the material is 316L stainless steel.

[0062] Previous research estimated the influence of the inner diameter of the inner migration loop in COMSOL simulation software (i.e., COMSOL multiphysics simulation software), among which the design structure was as follows. Figure 8 As shown in (a), the spatial structure design requirements of the inner migration ring are the same as those described above. By applying a gradient potential to the inner migration ring, a migration electric field (i.e., gradient electric field) of 50V / mm is generated in the standard area at the center of the inner migration tube 110. Since the uniformity of the electric field gradually decreases from the center to the periphery, as long as the inner diameter of the inner migration ring is designed appropriately, the problem can be solved. That is, the inner diameter of the semicircle. This ensures that the electric field uniformity at the boundary of the standard region meets the requirements, thus guaranteeing the electric field in the intermediate region. The model extracted four inner migration loops at the center, with equipotential lines distributed as follows: Figure 8 As shown in (b), the component (Ex) of the electric field along the x-axis at the boundary of the standard region, i.e., the line y = 7.5 mm, is extracted, and the result is presented in... Figure 8 In (c), it can be seen that the electric field intensity Ex along the ion transport direction (i.e., the first direction) exhibits a periodic variation with the x-coordinate consistent with the structure. This is due to the stacked ring structure. The larger the value, the smaller the electric field strength deviation (fluctuation amplitude). The summary results are as follows: Figure 8 As shown in (d) in the figure, when When the value is greater than 25 mm, the electric field strength deviation is less than 10. -2 Using the V / mm order of magnitude and incorporating the average value of ion characteristic properties, with a total migration time of 40ms, it can be deduced from the migration rate formula that, under this deviation condition, the migration time difference between ions located at the edge and center of the standard region will not exceed 0.01ms, and the relative error is less than 1‰.

[0063] The parallel electrode strips (i.e., the two straight segments) of the inner migration ring 111 serve to ensure that the electric field in the standard region is consistent with that in the unwindowed region. Due to space constraints imposed by structures such as the outer shielding tube 120, the length of the parallel electrode strips (i.e., the two straight segments) should be as short as possible while still meeting certain conditions. To facilitate quantification of the impact of the parallel electrode strip length on performance, this embodiment defines the relative error rate of the potential of the parallel electrode strips (i.e., the two straight segments) of the inner migration ring 111. ,in and These are the potentials at the inner and outer poles of the standard region, respectively. In the inner migration tube 110 with the side-opening window, the symmetry of the structure indicates... and It is the location with the greatest potential difference within the standard area, such as Figure 9 As shown in (a) of the simulation, the length of the parallel electrode strip is... (i.e., the lengths of the two straight line segments) )and Relationship such as Figure 9 As shown in (b) of the figure, it can be seen from the simulation results that with the development of the simulation, the simulation results show that ... Increase By reducing the length and selecting 70 mm, the error rate can be less than 1‰.

[0064] like Figure 6 As shown, in some embodiments of the present invention, the spacing between two adjacent inner migration rings 111 It is configured to maintain the continuity of the gradient electric field while ensuring structural strength. Specifically, the spacing between two adjacent inner migration rings 111 The spacing is 1 mm to 5 mm. This small spacing (1 mm to 5 mm) allows for a denser voltage distribution between the inner migration rings 111, resulting in a nearly continuous axial electric field. This avoids the stepped electric field distortion caused by excessive spacing, improving the stability of ion migration velocity and reducing mobility calculation errors. The dense electric field lines formed by the small-spacing inner migration rings constrain the radial diffusion of the ion beam, keeping the ion cloud close to the axial center. Ions, constrained by the electric field, have less contact with the tube wall, avoiding signal attenuation caused by adsorption or neutralization. The small spacing also allows for high field strength at a lower total voltage, reducing the size and energy consumption of the high-voltage power supply.

[0065] Optionally, the spacing between two adjacent inner migration rings 111 The spacing can be 1 mm, 5 mm, or 3 mm. Preferably, the spacing between two adjacent inner migration rings 111 is 5 mm.

[0066] In some embodiments of the present invention, the thickness of the inner migration ring 111 It is configured to ensure mechanical support strength without significantly distorting the electric field distribution. Specifically, the thickness of the inner migration ring 111... The thickness ranges from 0.5 mm to 1 mm. A thin inner migration ring of 0.5 mm to 1 mm reduces electric field distortion at the electrode edges, ensuring a highly uniform axial electric field along the ion migration path. The thin inner migration ring has a low heat capacity, allowing for faster temperature equilibrium in an environmental control chamber. The thin inner migration ring also allows for the placement of more electrodes per unit length, improving migration path resolution without increasing the overall length.

[0067] Optionally, the thickness of the inner migration ring 111 It can be 0.5 mm, 1 mm, or 0.7 mm.

[0068] In some embodiments of the present invention, the thickness of the outer shielding tube 120 is 4 mm to 6 mm. This can prevent tube deformation caused by pressure fluctuations and prevent external electromagnetic fields from disrupting the electric field uniformity within the migration cavity 112.

[0069] Optionally, the thickness of the outer shielding tube 120 can be 4 mm, 6 mm, or 5 mm.

[0070] The design process of the outer shielding tube in this embodiment of the invention is as follows: The primary function of the outer shielding tube 120 and the outer diameter of the inner migration ring 111 is to shield potential interference. The main design parameters are the width and thickness of the outer shielding tube 120, the radial distance of the shielding gap 130, the width of the inner migration ring 111, and the outer diameter of the outer shielding tube 120. To ensure the shielding effect, the width of the outer shielding tube 120 should be the maximum value. Considering processing errors and air pressure resistance, the width W of the outer shielding tube 120 is set to 4.5 mm. Considering that the outer shielding tube 120 needs to be drilled during assembly, the thickness of the outer shielding tube 120 is set to 6 mm. The radial distance L of the shielding gap 130 is selected as 30 mm to provide sufficient space for the reflector. Through the above settings, it can be observed in the simulation that the width of the inner migration ring 111 has a minimal impact on the potential shielding effect (exceeding the maximum accuracy of the simulation). Therefore, setting the minimum value that meets the requirements is sufficient. Figure 10 The difference in shielding performance between double-layer and single-layer migration tubes is shown. The central area shows the potential penetration. It can be seen that the double-layer migration tube of this invention has a much stronger shielding ability against the outside world than the single-layer migration tube with the same design parameters. It can almost make the electric field in the standard area unaffected by the external interference potential.

[0071] To further verify the physical performance of the double-shielded ion migration tube with in-situ non-destructive observation capability proposed in this embodiment of the invention, Figure 1 The consistency of the traditional single-layer closed-loop structure migration tube shown demonstrates that it achieves visual observation without sacrificing key electric field parameters. This embodiment also discloses numerical calculation verification based on electrostatic field theory: 1. Verification of the theoretical consistency of electric field uniformity: like Figure 1 and Figure 2 The conventional single-layer closed-loop structure migration tube shown uses a circular ring electrode, and its internal electric field can be considered an ideal uniform field. The U-shaped opening structure used in this embodiment of the invention has an edge effect at the opening, which is the main factor affecting the uniformity of the electric field. According to the exponential decay theory of the edge effect of the electrostatic field, for a spacing of... In a parallel electrode system, at a depth x from the electrode edge (i.e., at the opening of the inner migration ring 111 in this embodiment), the relative deviation of the electric field intensity caused by the edge structure is... The following attenuation formula is approximately satisfied: .

[0072] In the design parameters of this embodiment, the spacing between adjacent inner migration rings 111 The inner diameter of the semi-circular arc of the inner migration ring 111 is set to 5 mm. The minimum distance (x) from the center of the standard area to the edge of the opening is set to be at least 25 mm. Substituting these parameters into the formula, the calculation is as follows: ; .

[0073] Theoretical calculations show that the relative error of the electric field distortion introduced by the open structure has decreased to [value missing] by the time it reaches the central standard region. The magnitude is significantly lower than the typical requirements for electric field uniformity error in precision ion mobility spectrometers. to The order of magnitude. This is mathematically proven, as long as the ratio of the inner diameter to the ring spacing is maintained. The size is large enough that the electric field uniformity of the semi-open structure in this embodiment is physically consistent with that of the traditional closed ring structure within the standard area, fully meeting the requirements of high-precision measurement.

[0074] 2. Verification of the theoretical consistency of shielding effectiveness: To address potential external electric field interference introduced by the external viewing window on the outer shielding tube 120, this embodiment utilizes the "cutoff waveguide" effect formed by the double-layer structure for shielding. External interference electric field. When the field strength attenuation occurs inside a channel with a depth of L (i.e., the radial distance of the shielding gap 130) and a characteristic aperture of D (i.e., the equivalent aperture of the external observation window), it can be estimated using the small-aperture coupling theory: .

[0075] Where k is the geometric attenuation constant (typically around 3 for electrostatic field shielding structures). In this embodiment, the radial distance L of the shielding gap 130 is set to 30 mm, and the width D of the external observation window is set to no more than 15 mm (consistent with the effective cross-sectional size of the standard area), then the aspect ratio... Substitute the values ​​into the formula to calculate the shielding effectiveness: .

[0076] Calculations show that the intensity of the external interference electric field decreases to less than 0.25% of its original intensity after passing through the shielding gap in this embodiment (i.e., the decrease exceeds 50 dB). This result proves that by setting a shielding gap 130 of sufficient depth (e.g., 30 mm), this embodiment physically constructs a "Faraday cage" effect similar to that of a traditional fully enclosed metal tube. Although there is a physical opening in the structure, its electromagnetic properties are highly consistent with those of a traditional closed structure, ensuring the accuracy of ion mobility measurements.

[0077] In some embodiments of the present invention, the double-shielded ion migration tube for in-situ non-destructive observation also includes an environmental control box; the inner migration tube 110 and the outer shielding tube 120 are both disposed inside the environmental control box.

[0078] In this embodiment, by placing both the inner migration tube 110 and the outer shielding tube 120 inside an environmental control box, the environmental control box can maintain a constant temperature, eliminating the influence of temperature fluctuations on ion mobility. By filling with inert gas or precisely adjusting humidity, water molecules or other gases are prevented from interfering with the collision process between ions and neutral molecules. The environmental control box can provide a constant temperature, humidity, and pressure migration environment for ions, providing stable migration conditions and ensuring a standard environment for ion migration.

[0079] In some embodiments of the present invention, the double-shielded ion migration tube for in-situ non-destructive observation further includes a high-voltage electrode and a low-voltage electrode. The high-voltage electrode is located outside the migration cavity and abuts against the ion inlet end of the inner migration tube 110. The low-voltage electrode is located outside the migration cavity and abuts against the ion outlet end of the inner migration tube 110.

[0080] In this embodiment, a high-voltage electrode is provided at the inlet end of the inner migration tube 110, and a low-voltage electrode is provided at the outlet end, forming a strong electric field gradient along the axial direction. The high-voltage electrode (inlet end) applies a high voltage, creating a strong electric field attraction region at the inlet, which can capture and accelerate externally introduced ions, reducing ion diffusion loss at the inlet and improving ion utilization, especially suitable for low-concentration samples. The low-voltage design of the low-voltage electrode (outlet end) creates a smooth outlet electric field, avoiding scattering or accumulation of ions due to sudden deceleration. The strong electric field of the high-voltage electrode allows ions to quickly enter the inner migration tube, shortening the initial cloud width and reducing peak broadening caused by diffusion. The low-voltage electrode prevents secondary diffusion of ions due to abrupt changes in the electric field, ensuring symmetrical peak shape of the detection signal.

[0081] Figure 11 This is a schematic diagram illustrating the principle of in-situ, non-destructive observation of ion movement within an ion migration tube provided by the present invention, using a double-layer shield. Two detection points are randomly selected within the migration cavity 112, with detection point 1 and detection point 2 arranged along a first direction. The arrival time of the ion pulse at detection point 1 is recorded. And the time when the ion pulse arrives at detection point 2. Based on the known distance between the two detection bits The ion migration rate can be calculated according to formula (1). .

[0082] Formula (1).

[0083] Furthermore, by combining the known electric field strength E and gas environment parameters, the ion mobility K can be calculated using formulas (2) and (3).

[0084] Formula (2).

[0085] Formula (3).

[0086] In formula (3), The potential difference between detection point 1 and detection point 2.

[0087] Since the detection process does not consume ions, the same ion pulse can be further detected by subsequent instruments (such as a mass spectrometer), supporting multidimensional information coupling analysis. Furthermore, by adjusting the laser excitation wavelength and the detection filter, the double-shielded ion migration tube provided by this invention, which allows for in-situ non-destructive observation, can be used for simultaneous multi-channel non-destructive detection of different types of ions.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-layer shielded ion mobility tube for in-situ non-destructive observation, characterized in that, It includes an inner migration tube (110) and an outer shielding tube (120). The inner migration tube (110) includes a plurality of inner migration rings (111) and a plurality of resistors; the plurality of inner migration rings (111) are arranged at intervals along a first direction to form a migration cavity (112) with an inner observation window; two adjacent inner migration rings (111) are connected by the resistors to form a gradient electric field in the migration cavity (112) with a potential that gradually decreases along the first direction, the gradient electric field being used to drive ions entering the migration cavity (112) to move along the first direction; The outer shielding tube (120) is sleeved on the outside of the inner migration tube (110) and forms a shielding gap (130) between them. The outer shielding tube (120) is used to provide electromagnetic shielding. An external observation window is provided on the tube wall of the outer shielding tube (120), and the external observation window is correspondingly provided with the inner observation window.

2. The dual-layer shielded in-situ nondestructive observable ion transfer tube of claim 1, wherein, The migration cavity (112) has a standard area, and the cross-section of the standard area is a circle with a diameter of not less than 15 mm.

3. The dual-layer shielded in-situ nondestructive observable ion transfer tube of claim 1, wherein, The inner migration ring (111) includes: The arc segment is a semi-circular arc; Two straight line segments are arranged parallel to each other and spaced apart; the two ends of the arc segment extend along the tangent direction to form two straight line segments respectively, and the interval between the two straight line segments forms the inner observation window.

4. The dual-layer shielded in-situ nondestructive observable ion transfer tube of claim 3, wherein, The inner diameter of the semicircular arc Not less than 25 millimeters.

5. The double-layer shielded ion migration tube for in-situ non-destructive observation according to claim 3, characterized in that, length of the straight line segment not less than 70 mm.

6. The double-layer shielded ion migration tube for in-situ non-destructive observation according to claim 1, characterized in that, The distance between two adjacent inner migration rings (111) is 1 to 5 mm.

7. The double-layer shielded ion migration tube for in-situ non-destructive observation according to claim 1, characterized in that, The thickness of the inner migration ring (111) It ranges from 0.5 mm to 1 mm.

8. The double-layer shielded ion migration tube capable of in-situ non-destructive observation according to any one of claims 1 to 7, characterized in that, Also includes: The environmental control box contains both the inner migration tube (110) and the outer shielding tube (120).

9. The double-layer shielded ion migration tube for in-situ non-destructive observation according to any one of claims 1 to 7, characterized in that, Also includes: An insulating connector is disposed in the shielding gap (130), and the two ends of the insulating connector are respectively connected to the inner migration ring (111) and the outer shielding tube (120).

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