Ion mobility device, trace explosive detection apparatus, and x-ray security apparatus

Abstract

The application relates to the technical field of ion migration, and discloses an ion migration device, a trace explosive detection equipment and an X-ray security inspection machine, which are used to solve the problem that the migration tube in the prior art has poor focusing performance on ions entering a migration zone channel to a central area. The ion migration device comprises a base, an inner electrode and an outer electrode. The inner electrode is embedded in the base, and the part of the inner electrode exposed from the base is in a semispherical structure. The outer electrode is arranged at the outer periphery of the base, and the outer electrode has a cavity for accommodating the semispherical structure of the inner electrode. The gap between the inner wall of the cavity and the inner electrode forms an ion migration channel in a semicircular crown shape. The outer electrode is provided with an air inlet and an air outlet. An air inlet channel is arranged between the air inlet and the ion migration channel, and an air outlet channel is arranged between the air outlet and the ion migration channel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ion migration, in particular to an ion migration device, a trace explosive detection device and an X-ray security inspection machine. BACKGROUND

[0002] In recent years, in the field of trace explosive identification by gas detection, ion mobility spectrometers based on high-field asymmetric ion mobility spectrometry (FAIMS) are widely used, which can accurately distinguish and identify explosives. The migration tube is an important component of the high-field asymmetric ion mobility spectrometer. The existing migration tubes of the high-field asymmetric ion mobility spectrometer are generally divided into two types: one is a flat plate type migration tube, and the other is a cylindrical type migration tube. The flat plate type migration tube cannot realize ion focusing function. The ions close to the channel wall of the migration zone are more likely to touch the wall after entering the migration zone and lose electrons, which cannot reach the collection electrode, resulting in a large ion loss. The cylindrical type migration tube has ion focusing function, but the focusing performance is poor, which affects the passing rate of ions in the migration zone channel, reduces the ion intensity received by the collection electrode, and ultimately affects the detection performance of the ion mobility spectrometer. SUMMARY

[0003] The present application provides an ion migration device, a trace explosive detection device and an X-ray security inspection machine to solve the problem of poor focusing of ions entering the migration zone channel of the existing migration tube to the central region.

[0004] In a first aspect, an embodiment of the present application provides an ion migration device, which comprises a base, an inner electrode and an outer electrode.

[0005] The inner electrode is embedded in the base, and the part of the inner electrode exposed from the base is a hemispherical structure.

[0006] The outer electrode is arranged on the outer periphery of the base, and the outer electrode has a cavity for accommodating the hemispherical structure of the inner electrode. The gap between the inner wall of the cavity and the outer wall of the hemispherical structure forms an ion migration channel in the shape of a hemi-crown.

[0007] The outer electrode is provided with an air inlet and an air outlet. The air inlet and the ion migration channel are provided with an air inlet channel, and the air outlet and the ion migration channel are provided with an air outlet channel.

[0008] In the above embodiment, the ion migration device has an ion migration channel in the shape of a hemi-crown between the inner electrode and the outer electrode. The electric field in the ion migration channel is a non-uniform electric field, which has ion focusing function. Moreover, the electric field intensity at any position in the ion migration channel is proportional to the R value of the position.-2 Proportionally, this makes the electric field along the radial direction, the ion focusing effect is more significant, can improve the ion through the ion transfer channel, and then improve the detection accuracy and sensitivity of trace explosive substances.

[0009] Optionally, the gas inlet channel and the gas outlet channel are symmetrically arranged on both sides of the inner electrode and extend along the radial direction of the hemispherical structure of the inner electrode.

[0010] Optionally, the outer electrode comprises a first outer electrode and a second outer electrode, the first outer electrode is arranged on the top of the base, and the first outer electrode has the chamber;

[0011] The second outer electrode is connected with the first outer electrode and arranged around the base in the circumferential direction.

[0012] Optionally, the surface of the first outer electrode facing the second outer electrode is provided with a first groove, the surface of the second outer electrode facing the first outer electrode is provided with a second groove, and the surface of the base is provided with a third groove connected with the second groove and extending to the inner electrode, the first groove, the second groove and the third groove form the gas inlet channel and the gas outlet channel on both sides of the inner electrode.

[0013] Optionally, the second outer electrode is provided with a stepped hole, the stepped hole comprises a first hole section and a second hole section arranged in sequence in a direction away from the first outer electrode, and the aperture of the first hole section is larger than the aperture of the second hole section, and the base is at least partially located in the stepped hole and stopped at a stepped surface at the connection position of the first hole section and the second hole section;

[0014] The connecting end of the inner electrode penetrates out of the base.

[0015] Optionally, the base is provided with a connecting hole, the inner electrode comprises a first electrode part and a second electrode part, the first electrode part is at least partially exposed from the surface of the base to form the hemispherical structure, the second electrode part is connected with the first electrode part, and the second electrode part is a column penetrating the connecting hole.

[0016] Optionally, the surface of the base is provided with a sink, the sink is in communication with the connecting hole, the first electrode part comprises the hemispherical structure and an assembly structure connected with each other, wherein the hemispherical structure is the part exposed from the surface of the base, and the assembly structure is accommodated in the sink.

[0017] Optionally, the gas inlet channel and the gas outlet channel are provided with an arc-shaped transition zone at one end close to the inner electrode.

[0018] In a second aspect, the embodiments of the present application also provide a trace explosive detection device, which comprises an ionization device, the ion migration device according to any one of the above technical solutions, and an ion detection device, wherein the ionization device is arranged at an air inlet of the ion migration device, and the ion detection device is arranged at an air outlet of the ion migration device.

[0019] In the above embodiments, the ion migration device of the trace explosive detection device has the ion migration channel in the shape of a semi-crown, so that the focusing effect of ions is more significant in the screening stage of ions, the passing rate of ions through the ion migration channel can be improved, and the detection accuracy and sensitivity of trace explosive substances are further improved.

[0020] In a third aspect, the embodiments of the present application also provide an X-ray security inspection machine, which comprises a security inspection machine body and a trace explosive detection device, wherein the security inspection machine body has a security inspection channel, and the trace explosive detection device is arranged on the security inspection machine body and faces the security inspection channel.

[0021] In the above embodiments, the trace explosive detection device is applied to the X-ray security inspection machine, so that the X-ray security inspection machine can realize explosive trace detection of specific suspicious substances in a bag while realizing traditional X-ray image detection of forbidden and limited items such as guns and knives, and realizes one-time bag passing and multiple detection. In addition, the ion migration device of the trace explosive detection device has the ion migration channel in the shape of a semi-crown, the ion migration channel in the shape of a semi-crown has a good focusing effect on ions, can reduce ion loss of the sample to be detected, and can better realize detection and identification of explosive ions. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A structure schematic diagram of the ion migration device provided by the embodiments of the present application is shown in FIG. 1;

[0023] Figure 2 A cross-sectional view of the ion migration device shown in FIG. 2 is shown in FIG. 3; Figure 1

[0024] A cross-sectional structure schematic diagram of the ion migration device shown in FIG. 4 is shown in FIG. 5; Figure 3 Figure 1 A cross-sectional structure schematic diagram of the first outer electrode in the ion migration device shown in FIG. 6 is shown in FIG. 7;

[0025] Figure 4 Figure 3 A cross-sectional structure schematic diagram of the second outer electrode in the ion migration device shown in FIG. 8 is shown in FIG. 9;

[0026] Figure 5 A cross-sectional structure schematic diagram of the second outer electrode in the ion migration device shown in FIG. 8 is shown in FIG. 9; Figure 3

[0027] A cross-sectional structure schematic diagram of the second outer electrode in the ion migration device shown in FIG. 8 is shown in FIG. 9;​​Figure 6 for Figure 3 A schematic cross-sectional view of the internal electrode structure in the ion migration device shown.

[0028] Figure 7 for Figure 3 A schematic cross-sectional view of the base in the ion migration device shown.

[0029] Figure 8 for Figure 1 The diagram shows an ion channel formed by the combination of an inlet channel, an ion migration channel, and an outlet channel in the ion migration device shown.

[0030] Figure 9 A schematic diagram of an ion channel formed by the combination of an inlet channel, an ion migration channel, and an outlet channel in another ion migration device provided for an embodiment of the invention;

[0031] Figure 10 This is a schematic diagram of the composition of the trace explosives detection device provided in an embodiment of the present invention;

[0032] Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 The scan voltage waveform and the ion signal waveform of the test sample obtained during the test of the trace explosive detection device provided in the embodiments of the present invention are shown.

[0033] Figure label:

[0034] 1-Ion migration device;

[0035] 10-Base; 101-Connecting hole; 102-Sink; 103-Third groove;

[0036] 20 - Inner electrode; 201 - Hemispherical structure; 202 - Assembly structure; 21 - First electrode section; 22 - Second electrode section;

[0037] 30-External electrode; 301-Cavity; 302-Air inlet; 303-Air outlet; 31-First external electrode; 310-First groove; 32-Second external electrode; 320-Second groove; 321-Stepped hole; 3211-First hole section; 3212-Second hole section;

[0038] 40 - Ion migration channel; 50 - Inlet channel; 60 - Outlet channel; 70 - Arc-shaped transition zone;

[0039] 2-Ionization device; 3-Ion detection device; 4-Asymmetrical high voltage generator; 5-Compensation voltage generator. Detailed Implementation

[0040] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part instead of all of the embodiments of the present application. Based upon the embodiments in the present application, all the other embodiments obtained by those ordinarily skilled in the art without creative effort belong to the scope of the present application.

[0041] The embodiments of the present application provide an ion migration device to solve the problem that the migration tube in the prior art has poor focusing performance on ions entering the migration zone channel to the central area.

[0042] Referring to Figures 1-7 The ion migration device 1 comprises a base 10, an inner electrode 20 and an outer electrode 30. The inner electrode 20 is embedded in the base 10, and the part of the inner electrode 20 exposed from the base 10 is a hemispherical structure 201. The outer electrode 30 is arranged on the outer periphery of the base 10, and the outer electrode 30 has a cavity 301 for accommodating the hemispherical structure 201 of the inner electrode 20. The gap between the inner wall of the cavity 301 and the outer wall of the hemispherical structure 201 forms an ion migration channel 40 in the shape of a hemi-crown. The outer electrode 30 is provided with an air inlet 302 and an air outlet 303. An air inlet channel 50 is arranged between the air inlet 302 and the ion migration channel 40, and an air outlet channel 60 is arranged between the air outlet 303 and the ion migration channel 40.

[0043] Specifically, the base 10 of the ion mobility device 1 is made of insulating material, which supports the inner electrode 20 and insulates the inner electrode 20 and the outer electrode 30; the inner electrode 20 of the ion mobility device 1 is embedded in the base 10 and includes a hemispherical structure 201, which is the part of the inner electrode 20 exposed from the base 10; the outer electrode 30 of the ion mobility device 1 is arranged outside the base 10 and has a hemispherical cavity 301, which can accommodate the hemispherical structure 201 of the inner electrode 20 exposed from the base 10, and the inner wall of the cavity 301 and the outer wall of the hemispherical structure 201 have a gap therebetween, which forms an ion mobility channel 40 in the shape of a hemispherical crown, the outer electrode 30 is further provided with a gas inlet 302 and a gas outlet 303, the gas inlet 302 is communicated with the ion mobility channel 40 through a gas inlet channel 50, and the gas outlet 303 is communicated with the ion mobility channel 40 through a gas outlet channel 60, in the detection process, a high-voltage high-frequency asymmetric voltage and a compensation voltage are applied to the inner electrode 20, the outer electrode 30 is grounded, and the compensation voltage is scanned in a certain range, so that a high-frequency asymmetric electric field and a direct-current scanning electric field are formed between the inner electrode 20 and the outer electrode 30, the ion current generated by ionization enters the ion mobility channel 40 through the gas inlet 302 and the gas inlet channel 50 in sequence, in the ion mobility channel 40, different types of ions are separated mainly by the different characteristics of the ion mobility of different types of ions under high electric field varying with the electric field strength, and under the joint action of the high-frequency asymmetric electric field and the direct-current scanning electric field, only the ions meeting a certain scanning voltage can pass through the ion mobility channel 40 to reach the ion detection device 3, while other types of ions are neutralized by hitting the inner electrode 20 or the outer electrode 30, therefore, at the gas outlet 303 of the outer electrode 30, the ion current spectrum varying with the scanning voltage can be obtained by the ion detection device 3, that is, the high-frequency asymmetric waveform ion mobility spectrum spectrum, simply referred to as FAIMS spectrum, based on the obtained FAIMS spectrum of the to-be-detected substance, the corresponding relationship between the scanning voltage and the ion type stored in the database can be used to determine the type of the to-be-detected substance.

[0044] As can be seen from the foregoing, the ion migration device 1 has an ion migration channel 40 in the shape of a semi-circular crown, in the ion migration channel 40, the electric field along the radial direction is a non-uniform electric field, the electric field intensity at different positions is different, and gradually decreases from the inner electrode 20 to the outer electrode 30, under the joint action of the high-frequency asymmetric electric field and the direct-current scanning electric field, when the ion passes through the ion migration channel 40, if the ion is close to the inner electrode 20, the electric field force will force it to move to the central region between the two electrodes to be away from the inner electrode 20, if the ion is close to the outer electrode 30, the electric field force will force it to move to the central region between the two electrodes to be away from the outer electrode 30, that is, the focusing effect of the ion is generated, under the focusing effect of the ion, the ion can be gathered to the central region between the two electrodes, so that the ion separation ability is enhanced, and the separated ions are more concentrated, which is beneficial to the detection of the subsequent ion detection device 3, and can improve the sensitivity and accuracy of the ion detection device 3.

[0045] The effect of the ion focusing effect depends on the gradient change of the electric field along the radial direction in the ion migration channel 40, the greater the attenuation of the electric field intensity, the more ideal the focusing effect, in the ion migration channel 40, the electric field intensity at any position can be calculated by the following formula:

[0046]

[0047] In the formula, E is the electric field intensity at any position, Q is the total charge, ε0 is the dielectric constant, and R is the distance from the position to the center, it can be seen that under the condition that other parameters are unchanged, the electric field intensity E at any position is proportional to R-2 of the position, which makes the electric field in the ion migration channel 40 in the shape of a semi-circular crown along the radial direction produce a greater attenuation, and the focusing effect of the ion is more significant.

[0048] In order to more easily understand the advantages of the ion focusing effect of the ion migration device 1 based on the ion migration channel 40 in the shape of a semi-circular crown, the ion migration device 1 is compared with a cylindrical ion migration tube, the cylindrical ion migration tube includes a columnar inner electrode and a ring-shaped outer electrode, the gap between the columnar inner electrode and the ring-shaped outer electrode forms a cylindrical ion migration channel, in the ion migration channel, the electric field between the columnar inner electrode and the ring-shaped outer electrode along the radial direction is also a non-uniform electric field, the electric field intensity at any position can be calculated by the following formula:

[0049]

[0050] In the formula, E is the electric field intensity at any position, Q is the total charge, ε0 is the dielectric constant, R is the distance from the position to the center, and L is the axial length of the ion migration channel, it can be seen from the above formula that under the condition that other parameters are unchanged, the electric field intensity at any position is proportional to R -1Proportional, while in the embodiment of the present application, the electric field intensity E at any position in the ion migration channel 40 in the shape of a hemispherical crown is proportional to the R of the position where it is located -2 Proportional, thus, along the radial direction, the attenuation of the electric field generated in the ion migration channel 40 in the shape of a hemispherical crown is more significant than that in the ion migration channel in the shape of a cylinder.

[0051] Therefore, in the embodiment of the present application, the ion migration device 1 has a better ion focusing effect based on the ion migration channel 40 in the shape of a hemispherical crown than the ion focusing effect generated by the ion migration tube in the shape of a cylinder, reduces the probability of collision between ions and the inner electrode 20 or the outer electrode 30, reduces ion loss, and is more conducive to detection by the ion detection device 3, which can improve the sensitivity and accuracy of the ion detection device 3.

[0052] In the ion migration device 1, the outer electrode 30 is formed outside the inner electrode 20 to shield the influence of the external electric field on the internal electric field, and also reduces the radiation interference of the internal electric field on the external circuit of the system; and since the ion migration channel 40 is in the shape of a hemispherical crown structure, the space volume is small, which is more conducive to the miniaturization design of the whole.

[0053] In order to more clearly understand the ion migration device 1 provided by the embodiment of the present application, the present application will be described in detail in combination with the drawings.

[0054] In some embodiments, as shown in Figure 2 , Figure 3 The inlet and outlet of the ion migration channel 40 are located at the bottom edge of the ion migration channel 40 and are symmetrically arranged on both sides of the hemispherical structure 201 of the inner electrode 20.

[0055] Specifically, when the carrier gas pushes the ions to move, the ions will move along the shortest path between the inlet and the outlet with the carrier gas, and since the inlet and the outlet are located at the bottom edge of the ion migration channel 40 and are symmetrically arranged on both sides of the hemispherical structure 201 of the inner electrode 20, a plurality of ion migration paths of equal length and not affecting each other can be formed between the inlet and the outlet, and the migration path of the ions is close to half a circumference, so that the detection error caused by the length difference of the ion migration path is avoided, and the overall flow of the ions is increased, which is convenient for the detection and identification of trace ions.

[0056] The inlet of the ion migration channel 40 is located at the intersection position of the ion migration channel 40 and the gas inlet channel 50, and the outlet of the ion migration channel 40 is located at the intersection position of the ion migration channel 40 and the gas outlet channel 60. For example, as shown in Figure 8 The gas inlet channel 50 and the gas outlet channel 60 are symmetrically arranged on both sides of the inner electrode 20 and extend along the radial direction of the hemispherical structure 201 of the inner electrode 20; or, as shown in Figure 9As shown, the gas inlet channel 50 and the gas outlet channel 60 extend along the tangential direction of the hemispherical structure 201.

[0057] For the outer electrode 30, in some embodiments, as shown in Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, the outer electrode 30 includes a first outer electrode 31 and a second outer electrode 32, the first outer electrode 31 is arranged on the top of the base 10, and the first outer electrode 31 has a hemispherical cavity 301 which can accommodate the hemispherical structure 201 of the inner electrode 20 and form a hemispherical crown-shaped ion migration channel 40 with the hemispherical structure 201; the second outer electrode 32 is connected with the first outer electrode 31 and arranged circumferentially around the base 10, and the second outer electrode 32 and the first outer electrode 31 can be electrically connected through welding connection, flange connection, or through the use of conductive glue to bond the contact surface between the two, so that when the second outer electrode 32 is grounded, the first outer electrode 31 also has the effect of grounding.

[0058] From the structure, the second outer electrode 32 is provided with a hole structure for accommodating the base 10, and the base 10 is located in the hole structure and is surrounded circumferentially by the second outer electrode 32, for example, as shown in Figure 3 、 Figure 5 As shown, the second outer electrode 32 is provided with a stepped hole 321, the stepped hole 321 includes a first hole section 3211 and a second hole section 3212 arranged in sequence away from the first outer electrode 31, and the hole diameter of the first hole section 3211 is larger than that of the second hole section 3212, and the base 10 is at least partially located in the stepped hole 321 and stopped at the stepped surface at the connection position of the first hole section 3211 and the second hole section 3212; the inner electrode 20 is embedded in the base 10, and the connecting end of the inner electrode 20 passes out of the base 10.

[0059] Specifically, the first hole section 3211 and the second hole section 3212 are coaxially arranged, and since the hole diameter of the first hole section 3211 is larger than that of the second hole section 3212, the first hole section 3211 and the second hole section 3212 form a stepped surface at the connection position, and the base 10 can be arranged as a whole in the first hole section 3211 of the stepped hole 321 and stopped at the stepped surface, or part of the base 10 can be arranged in the first hole section 3211 of the stepped hole 321 and part of the base 10 can be arranged in the second hole section 3212 of the stepped hole 321, and the part of the base 10 located in the first hole section 3211 is stopped at the stepped surface, the stepped surface forms a support and a limit for the base 10, and the stepped surface and the base 10 can be bonded and fixed by glue.

[0060] The top surface of the base 10 can be flush or substantially flush with the top surface of the second outer electrode 32.

[0061] With continued reference to Figure 3 , Figure 5 The stepped hole 321 is a through hole, i.e. the stepped hole 321 penetrates the top surface and the bottom surface of the second outer electrode 32, so that when the connecting end of the inner electrode 20 is passed out of the base 10, the passed-out part will be located in the second hole section 3212, and in the second hole section 3212, a wire harness can be arranged to connect the inner electrode 20 with the asymmetric high-voltage generator 4 and the compensation voltage generator 5.

[0062] As known from the foregoing, the gas inlet channel 50 can communicate the gas inlet port 302 on the surface of the outer electrode 30 with the ion migration channel 40, and the gas outlet channel 60 can communicate the gas outlet port 303 on the surface of the outer electrode 30 with the ion migration channel 40. On the basis of the outer electrode 30 including the first outer electrode 31 and the second outer electrode 32, the formation of the gas inlet channel 50 and the gas outlet channel 60 is as shown in Figure 3 , Figure 4 , Figure 5 , Figure 7 The surface of the first outer electrode 31 facing the second outer electrode 32 is provided with a first groove 310, the surface of the second outer electrode 32 facing the first outer electrode 31 is provided with a second groove 320, and the surface of the base 10 is provided with a third groove 103 connected with the second groove 320 and extending towards the inner electrode 20, and the first groove 310, the second groove 320 and the third groove 103 form the gas inlet channel 50 and the gas outlet channel 60 on both sides of the inner electrode 20.

[0063] As can be seen from the cross-sectional view of the ion migration device shown in Figure 2 , the central axis of the gas inlet channel 50 and the central axis of the gas outlet channel 60 coincide and pass through the center of the hemispherical structure 201, so that after the ions enter the ion migration channel 40 from the gas inlet channel 50, the movement trajectories of the ions in the ion migration channel 40 are all close to half a circle, and finally the ions are emitted from the gas outlet channel 60, and the length difference of the movement trajectories of the ions is small.

[0064] Alternatively, in other embodiments, only the surface of the first outer electrode 31 facing the second outer electrode 32 can be provided with the first groove 310 to form the gas inlet channel 50, or only the surface of the second outer electrode 32 facing the first outer electrode 31 can be provided with the second groove 320, and the surface of the base 10 can be provided with the third groove 103 connected with the second groove 320 and extending towards the inner electrode 20 to form the gas inlet channel 50.

[0065] As shown in Figure 8As shown, when the ions enter the ion migration channel 40 from the gas inlet channel 50, the trajectory of the ions will change greatly at the intersection of the two, in order to ensure that the ions can smoothly pass through this area, reduce the head-on collision with the surface of the inner electrode 20, the end of the gas inlet channel 50 close to the inner electrode 20 is provided with an arc-shaped transition area 70, the arc-shaped transition area 70 makes the end of the gas inlet channel 50 close to the inner electrode 20 gradually transition to the surface of the inner electrode 20 in an arc surface, thereby reducing the head-on collision between the ions and the surface of the inner electrode 20, guiding the ions to pass smoothly, reducing ion loss, and for the same reason, the end of the gas outlet channel 60 close to the inner electrode 20 is also provided with an arc-shaped transition area 70.

[0066] For the base 10, the base 10 is made of an insulating material and plays a role of insulation between the inner electrode 20 and the outer electrode 30, and the base 10 can be made of polytetrafluoroethylene material, which can meet the high voltage insulation of about 10000V; the base 10 also plays a supporting role for the inner electrode 20, in some embodiments, as shown in Figure 3 、 Figure 6 、 Figure 7 As shown, the base 10 is provided with a connecting hole 101, the inner electrode 20 includes a first electrode part 21 and a second electrode part 22, the first electrode part 21 is at least partially exposed from the surface of the base 10 to form a hemispherical structure 201, and the second electrode part 22 is connected with the first electrode part 21, and the second electrode part 22 is a columnar body penetrating the connecting hole 101.

[0067] That is, the first electrode part 21 can only include the hemispherical structure 201, and the hemispherical structure 201 can be exposed from the surface of the base 10, or the first electrode part 21 can include a part that is not exposed from the surface of the base 10 in addition to the hemispherical structure 201, and this part is embedded in the base 10, thereby enhancing the stability of the hemispherical structure 201.

[0068] The second electrode part 22 is a columnar body and penetrates the connecting hole 101 of the base 10, as shown in Figure 7 The connecting hole 101 is a through hole, that is, the connecting hole 101 penetrates the top surface and the bottom surface of the base 10, and on the basis of the second outer electrode 32 provided with the stepped hole 321 for accommodating the base 10 introduced in the foregoing, the end of the second electrode part 22 can penetrate out of the connecting hole 101 and extend to the second hole section 3212 of the stepped hole 321, and in the second hole section 3212, by arranging a wire harness, the second electrode part 22 of the inner electrode 20 can be connected with the asymmetric high-voltage generator 4 and the compensation voltage generator 5.

[0069] Continuing to refer to Figure 3 、 Figure 6 、 Figure 7The surface of the base 10 is provided with a sink groove 102, the sink groove 102 is communicated with the connecting hole 101, the first electrode part 21 comprises a half-spherical structure 201 and an assembly structure 202 connected with each other, wherein the half-spherical structure 201 is exposed from the surface of the base 10, and the assembly structure 202 is accommodated in the sink groove 102.

[0070] The peripheral surface of the assembly structure 202 can be a part of a spherical surface, the spherical surface has the same surface curvature as the half-spherical structure 201, or the peripheral surface of the assembly structure 202 can also be a cylindrical surface. The assembly structure 202 can be accommodated in the sink groove 102 on the surface of the base 10, wherein the sink groove 102 and the connecting hole 101 form a stepped surface at the connecting position, the assembly structure 202 is stopped on the stepped surface, the stepped surface can support and limit the assembly structure 202, so that the inner electrode 20 is relatively stable.

[0071] Based on the same technical concept, the embodiment of the present application also provides a trace explosive detection device, which comprises an ionization device 2, the ion migration device 1 in any one of the above technical solutions, and an ion detection device 3.

[0072] The functional block diagram of the trace explosive detection device is shown in Figure 10 Some modules such as pump driving, flow detection, temperature detection, ion concentration detection are omitted, the trace explosive detection device can correspondingly complete the three core links of ion signal generation, screening and detection through the ionization device 2, the ion migration device 1 and the ion detection device 3, wherein the ionization device 2 can specifically use corona technology to ionize the sample gas which may contain explosives, the ion flow formed after ionization enters the ion migration device 1, in the ion migration device 1, the inner electrode 20 and the outer electrode 30 form a hemi-crown-shaped ion migration channel 40, after the ion flow enters the ion migration channel 40, different types of ions are separated mainly by using the different characteristics that the migration rate of different types of ions changes with the electric field strength under high electric field, and under the joint action of high-frequency asymmetric electric field and direct-current scanning electric field, only the ions meeting certain scanning voltage can pass through the ion migration channel 40 to reach the ion detection device 3, and other types of ions are neutralized by hitting the inner electrode 20 or the outer electrode 30, therefore, at the outlet 303 of the outer electrode 30, the ion detection device 3 can obtain the spectrum of the ion flow changing with the scanning voltage, that is, the high-frequency asymmetric waveform ion mobility spectrum, simply referred to as FAIMS spectrum, based on the obtained FAIMS spectrum of the to-be-detected substance, the FAIMS spectrum of various explosive ions known in advance is compared, if the comparison result is the same, it is determined that the to-be-detected substance contains explosive ions, if the comparison result is different, it is determined that the to-be-detected substance does not contain explosive ions.

[0073] Moreover, based on the structural features of the ion migration channel 40 in the form of a semi-crown, the ion migration channel 40 has a good ion focusing effect, so that the ion separation capability is enhanced, and the separated ions are more concentrated, which is conducive to the detection of the subsequent ion detection device 3, and can improve the sensitivity and accuracy of the ion detection device 3.

[0074] In order to verify the effectiveness of the trace explosive detection device with the ion migration channel 40 in the form of a semi-crown, the device is tested, and the experimental parameters used in the test are as follows:

[0075] (1) Asymmetric high-voltage waveform Vs: Vpp=6000V, f=167KHz;

[0076] (2) Compensated voltage sweep waveform Vc: initial voltage 0V, final voltage 18V, triangular wave duration 500ms;

[0077] (3) Air pump: speed 30mL / s, converted to ion drift speed 1m / s;

[0078] (4) Corona module: voltage -4000V DC, needle tip 0.07mm diameter carbon needle;

[0079] (5) Test sample: trinitrotoluene (TNT), nitroglycerin (NG), pentaerythritol tetranitrate (PETN), hexogen (RDX), and the sampling amount of the four samples is 100ng.

[0080] The test result graph is shown in Figures 11-15 , wherein, Figure 11 , the line graph is a scanning voltage waveform graph, and the curve graph is an ion signal waveform graph when the explosive ions are not contained in the measured sample; Figure 12 , the line graph is a scanning voltage waveform graph, and the curve graph is an ion signal waveform graph when trinitrotoluene (TNT) is contained in the measured sample, Figure 13 , the line graph is a scanning voltage waveform graph, and the curve graph is an ion signal waveform graph when nitroglycerin (NG) is contained in the measured sample; Figure 14 , the line graph is a scanning voltage waveform, and the curve graph is an ion signal waveform graph when pentaerythritol tetranitrate (PETN) is contained in the measured sample; Figure 15 , the line graph is a scanning voltage waveform graph, and the curve graph is an ion signal waveform graph when hexogen (RDX) is contained in the measured sample, Figures 11-15 , the abscissa of the line graph is time, and the ordinate is voltage, and the abscissa of the curve graph is time, and the ordinate is ion signal intensity.

[0081] From the test results, it can be seen that the corona ionization can effectively ionize the molecules of the sample under test, and can be used in cooperation with the semi-hemispherical crown ion migration channel 40. Since the sample under test used in the test is in the order of 100 ng, which belongs to the category of trace detection, the amplitude of the final signal is in the range of 200 mV-300 mV, indicating that the focusing effect of the semi-hemispherical crown ion migration channel 40 is good, and a large amount of sample ions are not lost, and the system can better realize the detection and identification of explosive molecules.

[0082] Based on the same technical concept, the embodiment of the present application also provides an X-ray security inspection machine, which comprises a security inspection machine body and a trace explosive detection device, the security inspection machine body has a security inspection channel, and the trace explosive detection device is arranged on the security inspection machine body and faces the security inspection channel.

[0083] In the trace explosive detection device used by the X-ray security inspection machine, the ion migration device 1 has a semi-hemispherical crown ion migration channel 40, the semi-hemispherical crown ion migration channel 40 has a good focusing effect on ions, can reduce the ion loss of the sample under test, and thus better realizes the detection and identification of explosive ions, and since the ion migration channel 40 has a semi-hemispherical crown structure, the space volume is small, which is more conducive to the miniaturization design of the whole, and the volume of the original sensor can be reduced to 1 / 3. By applying the trace explosive detection device to the X-ray security inspection machine, at least two disadvantages of the existing trace explosive device are solved, one is that the focusing effect of the ion generated by different types of substances is poor, which leads to that the time difference of the ions of different types of substances reaching the receiving end is too close, and the curve waveform of the ion migration spectrum generated is not significant, thereby affecting the comparison effect with the pre-known FAIMS spectrum of various explosives; the other is that the volume is too large, which is not convenient to install on the X-ray security inspection machine.

[0084] The X-ray security inspection machine applies the nonlinear ion migration spectrum trace substance detection technology to the inspection of related articles in the line and the bag, so that the X-ray security inspection machine can not only realize the traditional X-ray image detection of prohibited and restricted articles such as guns and knives, but also can realize the trace explosive detection of specific suspicious substances in the bag, realizes one-time bag passing and multiple detection, and has important value in places such as airports, customs and anti-terrorism departments.

[0085] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. An ion migration device, characterized in that, Includes base, inner electrode, and outer electrode; The inner electrode is embedded in the base, and the portion of the inner electrode protruding from the base is a hemispherical structure; The outer electrode is disposed on the outer periphery of the base, and the outer electrode has a cavity with a hemispherical structure for accommodating the inner electrode. The gap between the inner wall of the cavity and the outer wall of the hemispherical structure forms an ion migration channel in the shape of a hemispherical crown. The external electrode is provided with an air inlet and an air outlet. An air inlet channel is provided between the air inlet and the ion migration channel, and an air outlet channel is provided between the air outlet and the ion migration channel. The external electrode includes a first external electrode and a second external electrode, the first external electrode being disposed on the top of the base and having the cavity; The second external electrode is connected to the first external electrode and is arranged circumferentially around the base; The surface of the first outer electrode facing the second outer electrode has a first groove, the surface of the second outer electrode facing the first outer electrode has a second groove, and the surface of the base has a third groove that connects to the second groove and extends to the inner electrode. The first groove, the second groove, and the third groove form the air inlet channel and the air outlet channel on both sides of the inner electrode. The base is provided with a connection hole, and the inner electrode includes a first electrode part and a second electrode part. The first electrode part is at least partially exposed from the surface of the base to form the hemispherical structure. The second electrode part is connected to the first electrode part, and the second electrode part is a column that passes through the connection hole. The second external electrode is provided with a stepped hole, the stepped hole including a first hole segment and a second hole segment arranged sequentially in a direction away from the first external electrode, and the diameter of the first hole segment is larger than the diameter of the second hole segment. The base is at least partially located in the stepped hole and stops at the stepped surface at the connection position of the first hole segment and the second hole segment; the base and the stepped surface are fixedly connected. The connecting end of the internal electrode protrudes from the base; The stepped hole is a through hole, and the stepped hole penetrates the top and bottom surfaces of the second external electrode; The second external electrode is electrically connected to the first external electrode.

2. The ion migration device as described in claim 1, characterized in that, The air intake channel and the air outlet channel are symmetrically arranged on both sides of the inner electrode, and both extend in the radial direction along the hemispherical structure of the inner electrode.

3. The ion migration device as described in claim 1 or 2, characterized in that, The base surface is provided with a recessed groove, which communicates with the connecting hole. The first electrode part includes the hemispherical structure and the assembly structure connected to each other, wherein the hemispherical structure is the part exposed from the base surface, and the assembly structure is accommodated in the recessed groove.

4. The ion migration device as described in claim 1 or 2, characterized in that, An arc-shaped transition zone is provided at one end of the air intake channel and the air outlet channel near the inner electrode.

5. A trace explosive detection device, characterized in that, It includes an ionization device, an ion migration device as described in any one of claims 1 to 4, and an ion detection device, wherein the ionization device is disposed at the inlet of the ion migration device, and the ion detection device is disposed at the outlet of the ion migration device.

6. An X-ray security inspection machine, characterized in that, The device includes a security inspection machine body and a trace explosive detection device as described in claim 5, wherein the security inspection machine body has a security inspection channel, and the trace explosive detection device is disposed on the security inspection machine body and faces the security inspection channel.

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