Coaxial dielectric barrier discharge micro-plasma multi-dimensional element compound detection device

Abstract

The invention discloses a coaxial dielectric barrier discharge micro-plasma multi-dimensional element compound detection device which comprises a capillary column assembly and a capillary column interface assembly, the capillary column assembly is provided with a gas transmission channel extending in the axial direction of the capillary column assembly, one end of the capillary column assembly is a capillary gas inlet end, and the other end of the capillary column assembly is connected to the capillary column interface assembly. A conical contraction connector is arranged in the capillary column connector assembly, and the conical contraction connector is gradually transited from the large section to the small section in the gas flowing direction. The plasma discharge cavity is communicated with the capillary column interface assembly and extends along the axial direction; and a first electrode and a second electrode are wound outside the plasma discharge cavity. And a medium tube is arranged between the first electrode and the second electrode. And the first electrode and the second electrode are electrically connected with a high-voltage converter power supply. One end of the plasma discharge cavity away from the capillary column interface assembly is provided with a plasma lighting window; an optical detection assembly is arranged on the outer side of the plasma discharge cavity.

Description

Technical Field

[0001] This invention belongs to the field of gas analysis and plasma detection technology, specifically relating to a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device. Background Technology

[0002] Gas chromatography, as a mature separation and analysis technique, is widely used in environmental monitoring, industrial process control, electrochemical system safety assessment, and material failure analysis due to its high separation efficiency and wide applicability. In a gas chromatography system, after the sample gas is separated by a capillary column, each component flows out sequentially from the capillary column outlet and enters the detector for response signal acquisition and analysis. Therefore, the detector's structure, response mechanism, and matching method with the capillary column directly affect the detection sensitivity, repeatability, and stability of the gas chromatography system.

[0003] There are many types of gas chromatography detectors available, including thermal conductivity detectors, flame ionization detectors, electron capture detectors, and plasma-based optical detectors. Among them, dielectric barrier discharge plasma detectors have gained increasing attention in recent years because they do not require additional fuel gas, can operate under atmospheric or near-atmospheric pressure conditions, and are responsive to a variety of gas components.

[0004] However, when applying dielectric barrier discharge detection technology to gas chromatography systems, especially in scenarios where it is coupled with capillary columns, existing technologies still face a series of engineering problems that have not yet been effectively solved.

[0005] First, from the perspective of gas flow characteristics, the gas flow rate at the output end of a capillary column is typically small, and the gas channel diameter is extremely narrow, resulting in a near-laminar flow. When this trace amount of gas directly enters a relatively large discharge cavity, it often forms a suddenly expanding flow channel structure in the interface region, causing a sharp drop in gas velocity and generating local eddies or stagnant zones. This instability in the flow state directly affects the uniformity of gas concentration distribution within the discharge region, leading to fluctuations in discharge intensity and instability in the optical signal.

[0006] Secondly, from the perspective of discharge structure, existing dielectric barrier discharge detection devices mostly adopt relatively open or large discharge cavity structures. Their design intention is often to ensure that the discharge is easy to establish, without fully considering the flow rate and spatial scale of the gas output from the capillary column. When the discharge cavity volume is too large, it is difficult to accurately control the residence time of the gas in the discharge region, which can easily lead to memory effects or gas residue, thereby reducing detection repeatability and being particularly unfavorable for the accurate detection of continuous elution peaks.

[0007] Furthermore, from a structural matching perspective, the connection between the capillary column and the discharge cavity in existing technologies is usually quite simple, often employing a straight-through connection or a short straight tube connection, lacking a transitional structural design tailored to the characteristics of the gas output from the capillary column. This abrupt connection not only easily causes instability in the gas flow field but may also create an electric field distortion region at the discharge cavity inlet, making it difficult to control the position and shape of the discharge region.

[0008] Furthermore, regarding electrode structure design, while existing dielectric barrier discharge detectors offer various electrode configurations, a systematic structural design solution is still lacking for applications using capillary columns. This solution addresses the challenge of simultaneously achieving stable discharge, effective electrode isolation, and smooth gas flow within a limited space. While some devices can achieve discharge, their complex structures and large size make it difficult to integrate them into a compact, unified structure with the capillary column.

[0009] Finally, from a functional perspective, existing detectors for gas chromatography-plasma emission detectors (GC-PEP detectors) often only acquire signals for single elements, with few reports on the detection of small molecule gaseous compounds such as hydrogen, oxygen, and nitrogen. Finding the emission lines of hydrogen, oxygen, and nitrogen in the ultraviolet region is crucial.

[0010] Therefore, in summary, existing technologies still have shortcomings in the following aspects: Firstly, there is a lack of a discharge cavity inlet structure that can be effectively matched with the output end of the capillary column, making it difficult to ensure a smooth transition of gas from the capillary column to the discharge region. Secondly, the design of the discharge cavity volume and structure is unreasonable, making it difficult to ensure both stable discharge and rapid gas passage and signal repeatability. Third, the arrangement of electrodes and dielectric structures lacks a coaxial and miniaturized design approach for detecting small flow rates of gas.

[0011] Fourth, the design for simultaneously measuring the atomic emission spectra of small molecule gas compounds such as hydrogen, oxygen, and nitrogen needs further research.

[0012] To address the aforementioned issues, a novel structure for a dielectric barrier discharge micro-plasma multidimensional element compound detection device is urgently needed. By coordinating the design of the capillary column interface, discharge cavity, and electrode configuration, the structural problems of poor matching between the capillary column and the plasma detection unit, unstable discharge, and insufficient detection repeatability can be solved. Summary of the Invention

[0013] The purpose of this invention is to overcome the above-mentioned shortcomings in the prior art and provide a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device. By systematically designing the transition structure of the gas output from the capillary column, the volume of the discharge cavity, and the electrode arrangement, the trace amount of gas output from the capillary column can stably and continuously enter the plasma discharge region, thereby forming a stable dielectric barrier discharge micro-plasma in a small volume cavity.

[0014] To achieve the above objectives, the present invention adopts the following technical solution: A coaxial dielectric barrier discharge microplasma multidimensional element compound detection device includes a capillary column assembly and a capillary column interface assembly. The capillary column assembly has a gas transmission channel extending along its axial direction. One end of the capillary column assembly is a capillary gas inlet, and the other end is connected to the capillary column interface assembly. A conical contraction interface is provided inside the capillary column assembly, which gradually transitions from a large cross-section to a small cross-section along the gas flow direction. The conical contraction interface is used to connect the capillary column and guide the gas from the capillary column assembly into the plasma discharge cavity. The plasma discharge cavity is connected to the capillary column interface assembly and extends axially. A first electrode and a second electrode are wound around the outside of the plasma discharge cavity, and the first electrode and the second electrode are arranged at intervals along the gas flow direction. A dielectric tube is provided between the first electrode and the second electrode for electrical isolation to form a dielectric barrier discharge structure. The first electrode and the second electrode are electrically connected to a high-voltage converter power supply, which is used to excite the formation of microplasma in the plasma discharge cavity. A plasma light-collecting window is provided at the end of the plasma discharge cavity away from the capillary column interface assembly. An optical detection assembly is provided on the outside of the plasma discharge cavity.

[0015] Furthermore, the capillary column assembly and the capillary column interface assembly are connected by an axial insertion and compression method. The insertion area is provided with an insertion structure to limit radial offset. The insertion structure is used to ensure that the axis of the capillary column assembly is coaxial with the axis of the plasma discharge cavity.

[0016] Furthermore, the conical contraction interface is directly connected to the plasma discharge cavity in the axial direction, so that the gas forms a continuously contracting flow channel with a "Venturi" nozzle structure during the process of entering the plasma discharge cavity from the capillary column assembly, which is used to reduce the turbulent area during the gas flow process.

[0017] Furthermore, the first electrode and the second electrode are coaxially arranged along the axial direction of the plasma discharge cavity to form a coaxial dielectric barrier discharge configuration. The first electrode and the second electrode are arranged on the outside of the dielectric tube to physically isolate them from the gas inside the dielectric tube and prevent electrode carbon deposition.

[0018] Furthermore, the effective discharge region length of the first electrode and the second electrode in the axial direction is less than the axial length of the plasma discharge cavity, so that the gas has a buffer transition section when entering and leaving the discharge region.

[0019] Furthermore, the dielectric tube extends axially through several regions of the plasma discharge cavity and forms a gap with the inner wall of the plasma discharge cavity to define the radial dimension of the discharge region and suppress the generation of arc discharge.

[0020] Furthermore, the plasma discharge cavity is a small-volume cavity structure, with its axial length and radial dimensions on the order of millimeters. The plasma discharge cavity allows gas to pass through the discharge region rapidly, reducing the impact of plasma volume fluctuations on the stability of optical detection.

[0021] A detection method using a coaxial dielectric barrier discharge micro-plasma multi-dimensional elemental compound detection device includes the following steps: A: The gas to be detected is introduced into the capillary column assembly through the capillary inlet end, so that the gas flows along the axial transmission channel of the capillary column assembly. B: The gas enters the conical contraction port through the capillary column interface assembly, and under the guidance of the conical contraction port, it transitions from the capillary column assembly into the plasma discharge chamber. C: A high-voltage electrical signal is applied to the first and second electrodes through the high-voltage converter power supply, and a stable dielectric barrier micro-plasma is formed in the plasma discharge cavity under the blocking effect of the dielectric tube. D: During the process of gas passing through the plasma discharge cavity, optical signals generated by plasma discharge are continuously acquired using optical detection components.

[0022] Furthermore, during the formation of dielectric barrier microplasma, the output state of the high-voltage converter power supply is adjusted to maintain a stable discharge state between the first electrode and the second electrode.

[0023] Furthermore, the optical detection component is equipped with multi-dimensional element simultaneous acquisition, and performs signal acquisition for elements such as hydrogen (-278nm), oxygen (-205nm), nitrogen (-236nm), and carbon (-388nm).

[0024] Furthermore, the gas, after optical signal acquisition, is discharged from the detection device through the plasma light-collecting window.

[0025] Beneficial effects: This invention, by setting the first and second electrodes coaxially and placing a dielectric tube between them to form a dielectric barrier discharge structure, concentrates and controls the discharge region, which is beneficial for establishing stable micro-plasma discharge in a smaller space, thereby improving the stability and repeatability of the detection process. The interface assembly features a tapered constriction interface, which effectively shapes the gas before it enters the plasma discharge chamber, reducing the impact of gas flow disturbances on the discharge state and avoiding signal fluctuations caused by flow field instability.

[0026] Designing the plasma discharge chamber as a small-volume structure that matches the output flow rate of the capillary column effectively reduces the dead volume of the detection system and lowers the residence time of gas in the detection area, thereby improving the detection response speed and time resolution. By integrating the optical detection component with the plasma discharge chamber, the detection process is based on the optical signal generated by the discharge, eliminating the need for complex current or voltage sampling structures. This simplified structure offers strong anti-interference capabilities and is suitable for stable coupling with gas chromatography systems.

[0027] Because the detection device has a compact structure and clear connections, and the detection method is implemented based on the operation of the device, the overall system is easy to integrate and can adapt to various elemental gas compound chromatography application scenarios. Attached Figure Description

[0028] Figure 1 A schematic diagram of a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device; Figure 2 Schematic diagram of a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device; Figure 3 Discharge effect diagram of coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device; Figure 4 Implementation effect diagram of the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device; Figure 5 Performance diagram of a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device. Detailed Implementation

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention, and are intended to enable those skilled in the art to fully understand and implement the present invention, and do not constitute a limitation on the scope of protection of the present invention.

[0030] like Figures 1 to 3As shown, the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device provided in this embodiment includes, in sequence along the gas flow direction, a capillary column assembly 300, a capillary column interface assembly 310, a plasma discharge cavity 400, and an optical detection assembly 900 disposed outside the discharge cavity.

[0031] In this coaxial dielectric barrier discharge microplasma multidimensional element compound detection device, the gas flow path, discharge structure, and optical detection position are spatially unified, enabling the gas to enter the discharge region along a basically coaxial direction after being output from the capillary column, and to complete discharge excitation and optical signal acquisition during its passage through the discharge region. This overall coaxial and miniaturized structural design allows the device to achieve stable dielectric barrier discharge microplasma within a small volume, making it suitable for detecting trace gases output from capillary columns.

[0032] This device is typically used in conjunction with a gas chromatography system. The capillary column assembly 300 receives the output of the gas chromatography capillary column, while the capillary inlet 600 introduces the gas separated by gas chromatography into the detection device. Inside the device, the gas sequentially passes through a transition structure and a discharge structure before finally exiting through the plasma light-collecting window 700.

[0033] The capillary column assembly 300 is used to connect to the capillary column in the gas chromatography system, and forms an axially extending gas transmission channel inside. The inner diameter of this gas transmission channel matches the inner diameter of the output end of the capillary column, thereby ensuring that the gas does not undergo significant abrupt changes in flow state before entering the detection device.

[0034] One end of the capillary column assembly 300 forms a capillary inlet end 600, which can be connected to the output end of the gas chromatography capillary column via a ferrule, thread, or other sealing connection. The capillary column assembly 300 can use various millimeter-sized capillary tubes available on the market, commonly 0.53mm, 0.32mm, and 0.25mm.

[0035] In some embodiments, the capillary inlet 600 preferably adopts a structure that can achieve a reliable seal to prevent gas leakage during the detection process, thereby affecting the detection stability.

[0036] The other end of the capillary column assembly 300 is connected to the capillary column interface assembly 310. The capillary column interface assembly 310 is disposed between the capillary column assembly 300 and the plasma discharge chamber 400, and its main function is to achieve a smooth transition of the gas output from the capillary column to the interior of the discharge chamber.

[0037] In some embodiments, a tapered contraction interface 311 is formed inside the capillary column interface assembly 310. The tapered contraction interface 311 has a structure that gradually transitions from a larger cross-section to a smaller cross-section along the gas flow direction, allowing the gas to undergo a continuous and controlled flow channel contraction process before entering the plasma discharge chamber 400 from the capillary column assembly 300. The narrowest point of the tapered contraction interface 311 is between 0.1 mm and 0.5 mm.

[0038] By designing the tapered contraction interface 311, turbulence, stagnation, or backflow phenomena that occur when gas suddenly enters a larger volume space from a narrow channel can be effectively avoided, ensuring a relatively stable flow velocity distribution and flow direction when the gas enters the plasma discharge cavity 400. This is of great significance for the subsequent discharge stability.

[0039] The plasma discharge chamber 400 is located downstream of the capillary column interface assembly 310, and its overall structure is a small-volume cavity extending axially. In some embodiments, the axial length and radial dimension of the plasma discharge chamber 400 are both controlled within a small range to accommodate the low gas flow rate output from the capillary column. The plasma discharge chamber 400 can be made of quartz tube, with an inner diameter between 0.1 mm and 2 mm.

[0040] One end of the plasma discharge chamber 400 is connected to the capillary column interface assembly 310, allowing the gas guided by the conical contraction interface 311 to directly enter the interior of the discharge chamber; the other end forms a plasma light-collecting window 700, which is used to discharge the gas after the detection is completed.

[0041] By designing the discharge cavity as a small-volume structure, gas can pass through the discharge region rapidly, avoiding prolonged gas retention within the cavity and thus reducing the impact of gas residue or memory effects on the detection results. Furthermore, the small-volume cavity structure also helps improve the stability of the electric field distribution within the discharge region, making it easier to maintain the micro-plasma in a stable state.

[0042] A first electrode 100 and a second electrode 200 are located outside the dielectric tube 500. The first electrode 100 and the second electrode 200 are arranged at intervals along the gas flow direction, and their relative positions are basically consistent with the axial direction of the discharge cavity. The electrodes can be made of copper wire.

[0043] In some embodiments, the first electrode 100 and the second electrode 200 are preferably arranged coaxially, that is, the axes of the two electrodes are substantially coincident or parallel, thereby maintaining good radial symmetry of the discharge region. This coaxial structure is beneficial for forming a uniform discharge region and reducing discharge instability caused by uneven electric field.

[0044] A dielectric tube 500 is disposed between the first electrode 100 and the second electrode 200 to electrically isolate the two electrodes, thereby forming a dielectric barrier discharge structure. The dielectric tube 500 can penetrate at least a portion of the discharge cavity along the axial direction, and its material is preferably a material with good dielectric properties.

[0045] By placing a dielectric tube 500 between the electrodes, the discharge current can be effectively limited, preventing the formation of a continuous arc, thus allowing the discharge to exist stably in the form of micro-plasma. This dielectric barrier discharge method is particularly suitable for achieving stable discharge in small-volume cavities.

[0046] The first electrode 100 and the second electrode 200 are electrically connected to the high-voltage converter power supply 800. The high-voltage converter power supply 800 is used to convert the external input voltage into a high-voltage electrical signal suitable for dielectric barrier discharge and apply it between the two electrodes. For example, the high-voltage converter power supply 800 is powered by an AC high-voltage power supply to excite argon gas to generate micro-plasma.

[0047] During the operation of the detection device, a high-voltage electrical signal is applied to the first electrode 100 and the second electrode 200 through the high-voltage converter power supply 800. Under the blocking effect of the dielectric tube 500, a stable micro-plasma discharge state is formed in the discharge cavity.

[0048] In some implementations, the output mode of the high-voltage converter power supply 800 can be adjusted according to actual needs, such as using AC high voltage or pulsed high voltage to meet the discharge stability requirements under different detection scenarios.

[0049] The optical detection component 900 is located outside the plasma discharge cavity 400, corresponding to the discharge area. The optical detection component 900 is used to acquire the optical signals generated during the micro-plasma discharge process.

[0050] In some embodiments, the optical detection component 900 may include an optical acquisition unit and a signal processing unit connected thereto. The optical acquisition unit is used to receive the optical radiation signal generated during the discharge process, and the signal processing unit is used to process and output the acquired optical signal. By placing the optical detection component 900 outside the discharge cavity, stable acquisition of the discharge optical signal can be achieved without interfering with the discharge structure and gas flow.

[0051] like Figure 4As shown, the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device provided in this embodiment, with its plasma optical detection component 900, can simultaneously monitor multi-channel atomic / molecular emission lines, such as H2 (278nm), O (205nm), N (236nm), and C (388nm). In addition, it supports multidimensional detection, enabling the simultaneous identification of gases such as H2, O2, N2, CH4, CO, CO2, C2H4, and C2H6.

[0052] Based on this coaxial dielectric barrier discharge microplasma multidimensional element compound detection device, this embodiment also provides a coaxial dielectric barrier discharge microplasma detection method, the specific implementation process of which is as follows.

[0053] Before starting the detection, connect the detection device to the gas chromatography system, connecting the output end of the capillary column to the capillary inlet 600. Simultaneously, connect the high-voltage converter power supply 800 to the first electrode 100 and the second electrode 200, putting the device in a ready-to-start state.

[0054] During detection, the gas to be detected, after being separated by gas chromatography, first enters the capillary column assembly 300 and flows downstream along the gas transmission channel inside the capillary column assembly 300. Subsequently, the gas enters the capillary column interface assembly 310 and gradually transitions into the plasma discharge chamber 400 under the guidance of the tapered contraction interface 311.

[0055] When the gas enters the plasma discharge chamber 400, a high-voltage electrical signal is applied to the first electrode 100 and the second electrode 200 through the high-voltage converter power supply 800. Under the blocking effect of the dielectric tube 500, a stable dielectric barrier micro-plasma is formed inside the discharge chamber.

[0056] As the gas passes through the discharge region, the optical detection component 900 continuously acquires the optical signals generated by the micro-plasma discharge and outputs the acquired signals for subsequent analysis and processing. After detection, the gas exits the detection device through the plasma light-collecting window 700.

[0057] Through the synergistic combination of the above structures and methods, this embodiment can achieve the following technical effects: As the gas enters the discharge cavity from the capillary column assembly 300, it always flows along the controlled flow channel, avoiding flow field instability caused by abrupt changes in the flow channel structure. The discharge chamber adopts a small volume structure, which allows gas to pass through the discharge area quickly, thereby reducing the impact of discharge volume fluctuations and gas residues on detection stability. The coaxial dielectric barrier discharge structure makes the electric field distribution in the discharge region more uniform, which is conducive to the formation of a stable micro-plasma state. The optical detection component 900 is properly matched with the discharge area, making the optical signal acquisition process stable and reliable.

[0058] Based on the above implementation method, the specific structural form and relative arrangement of the first electrode 100 and the second electrode 200 can be adjusted according to actual application requirements.

[0059] In another embodiment, the first electrode 100 can be configured as an axially extending metal needle-shaped electrode with an outer diameter smaller than the inner diameter of the dielectric tube 500, such that the first electrode 100 is located inside the dielectric tube 500 and radially spaced from it. The second electrode 200 can be disposed on the outside of the dielectric tube 500 and form a ring structure by wrapping around it axially. With this structural form, the discharge area is mainly distributed within the radial gap of the dielectric tube 500, thereby forming a stable dielectric barrier discharge with a smaller discharge gap.

[0060] In another embodiment, both the first electrode 100 and the second electrode 200 can be configured as annular electrodes arranged axially spaced apart, isolated from each other by a dielectric tube 500. In this case, the discharge mainly occurs in the axial region between the two annular electrodes. This structural configuration is beneficial for forming a uniform discharge region within a shorter axial distance, thereby further shortening the overall length of the discharge cavity.

[0061] In the different embodiments described above, the specific material, thickness, and axial length of the electrode can be adjusted according to the required discharge intensity and stability requirements without affecting the overall technical concept of the present invention.

[0062] In the detection device of the present invention, the structural design of the plasma discharge cavity 400 not only accommodates the electrode and dielectric structure, but also plays a key role in the stability of gas flow.

[0063] Since the gas flow rate output from a gas chromatography capillary column is typically at the micro-level, if the discharge chamber volume is too large, it can easily lead to the formation of stagnant regions of gas inside the chamber, resulting in unstable discharge or drift in the detection signal. Therefore, this invention designs the discharge chamber 400 as a small-volume structure that matches the capillary output flow rate, ensuring continuous gas flow within the discharge region.

[0064] Meanwhile, the tapered contraction interface 311 in the capillary column interface assembly 310 plays a role in flow field shaping before the gas enters the discharge chamber, so that the gas streamlines are basically aligned along the axial direction before entering the discharge region, thereby reducing the impact of lateral disturbances on discharge stability.

[0065] By combining the above structures, micro-plasma discharge can be kept stable over a wide flow range, which significantly improves the applicability of the detection device from an engineering application perspective.

[0066] In actual testing, the testing method of the present invention can be divided into multiple operating stages to further illustrate its engineering implementation.

[0067] During the startup phase, the gas chromatography system is first turned on, allowing the carrier gas and sample gas to pass through the capillary column assembly 300 according to preset conditions. Simultaneously, the high-voltage converter power supply 800 is activated, gradually establishing discharge conditions between the first electrode 100 and the second electrode 200. During this phase, micro-plasma gradually forms and stabilizes inside the discharge chamber 400.

[0068] During the steady-state detection phase, the gas chromatography system operates stably, the micro-plasma continues to discharge, and the optical detection component 900 continuously acquires the optical signals generated by the discharge. At this time, the background signal is relatively stable and can be used as a reference baseline for subsequent sample detection.

[0069] When the target component, after chromatographic separation, enters the discharge chamber 400, it enters the peak detection stage. Due to the differences in the excitation characteristics of different gas components in the micro-plasma, the discharge optical signal will change accordingly over time, and the optical detection component 900 records this change in real time.

[0070] After the test is completed, the discharge recovery phase can begin. By maintaining the carrier gas to continue flowing through the discharge chamber 400, the discharge state is restored to a stable background level, preparing for the next test.

[0071] like Figure 5 As shown, the coaxial dielectric barrier discharge microplasma multidimensional element compound detection device provided in this embodiment, compared with traditional discharge cavities, significantly improves signal strength and detection sensitivity due to its small cavity design (especially its 1.0 mm inner diameter). It achieves more than twice the atomic emission of cylindrical dielectric barrier discharge and more than ten times the atomic emission of tip discharge plasma. The detection limits for H2, CO, CO2, CH4, C2H4, and C2H6 are 6, 0.3, 0.3, 0.5, 0.1, and 0.1 ppmv, respectively. It can achieve simultaneous, multidimensional, and highly sensitive detection of H2, O2, N2, and various organic gases.

[0072] Finally, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A coaxial dielectric barrier discharge micro-multidimensional element compound plasma detection device, characterized in that, The system includes a capillary column assembly (300) and a capillary column interface assembly (310). The capillary column assembly (300) has a gas transmission channel extending along its axial direction. One end of the capillary column assembly (300) is a capillary inlet end (600), and the other end is connected to the capillary column interface assembly (310). The capillary column interface assembly (310) has a conical constriction port (311) inside. The conical constriction port (311) gradually transitions from a large cross-section to a small cross-section along the gas flow direction. The conical constriction port (311) is used to connect to the capillary column assembly (300) and guide the gas from the capillary column assembly (300) into the plasma discharge chamber (400). The plasma discharge chamber (400) is connected to the capillary column interface assembly (310) and extends axially. 0) An externally wound first electrode (100) and second electrode (200) are arranged at intervals along the gas flow direction; a dielectric tube (500) is provided between the first electrode (100) and the second electrode (200), the dielectric tube (500) is used for electrical isolation to form a dielectric barrier discharge structure; the first electrode (100) and the second electrode (200) are electrically connected to a high-voltage converter power supply (800), the high-voltage converter power supply (800) is used to excite the formation of micro-plasma in the plasma discharge cavity (400); a plasma light-collecting window (700) is provided at one end of the plasma discharge cavity (400) away from the capillary column interface assembly (310); an optical detection assembly (900) is provided on the outside of the plasma discharge cavity (400).

2. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 1, characterized in that, The capillary column assembly (300) and the capillary column interface assembly (310) are connected by an axial insertion and compression method. The insertion area is provided with an insertion structure for limiting radial offset. The insertion structure is used to ensure that the axis of the capillary column assembly (300) is coaxial with the axis of the plasma discharge cavity (400).

3. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 1, characterized in that, The conical contraction port (311) is directly connected to the plasma discharge cavity (400) in the axial direction, so that the gas forms a continuously contracting flow channel of the Venturi nozzle structure during the process of entering the plasma discharge cavity (400) from the capillary column assembly (300), which is used to reduce the turbulent area during the gas flow process.

4. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 1, characterized in that, The first electrode (100) and the second electrode (200) are coaxially arranged along the axial direction of the plasma discharge cavity (400) to form a coaxial dielectric barrier discharge configuration. The first electrode (100) and the second electrode (200) are disposed on the outside of the dielectric tube (500) to physically isolate them from the gas inside the dielectric tube (500) and prevent electrode carbon deposition.

5. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 4, characterized in that, The effective discharge region length of the first electrode (100) and the second electrode (200) in the axial direction is less than the axial length of the plasma discharge cavity (400) so that the gas has a buffer transition section when entering and leaving the discharge region.

6. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 1, characterized in that, The dielectric tube (500) extends axially through several regions of the plasma discharge cavity (400) and forms a gap with the inner wall of the plasma discharge cavity (400) to define the radial dimension of the discharge region and suppress the generation of arc discharge.

7. The coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 1, characterized in that, The plasma discharge cavity (400) is a small-volume cavity structure. The axial length and radial dimension of the plasma discharge cavity (400) are in the millimeter range. The plasma discharge cavity (400) allows gas to pass through the discharge area quickly, reducing the impact of plasma volume fluctuations on the stability of optical detection.

8. A detection method for a coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device, characterized in that, The detection method using the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to any one of claims 1 to 7 includes the following steps: A: The gas to be detected is introduced into the capillary column assembly (300) through the capillary inlet (600), so that the gas flows along the axial transmission channel of the capillary column assembly (300); B: Gas enters the conical shrinkage port (311) through the capillary column interface assembly (310), and under the guidance of the conical shrinkage port (311), it transitions from the capillary column assembly (300) into the plasma discharge chamber (400). C: A high-voltage electrical signal is applied to the first electrode (100) and the second electrode (200) through the high-voltage converter power supply (800), and a stable dielectric barrier micro-plasma is formed in the plasma discharge cavity (400) under the blocking effect of the dielectric tube (500). D: During the process of gas passing through the plasma discharge cavity (400), the optical signal generated by the plasma discharge is continuously acquired using the optical detection component (900).

9. The detection method of the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 8, characterized in that, During the formation of the dielectric barrier microplasma, the output state of the high-voltage converter power supply (800) is adjusted to maintain a stable discharge state between the first electrode (100) and the second electrode (200).

10. The detection method of the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 8, characterized in that, The optical detection component (900) is used to simultaneously collect light emission signals of multidimensional elements, including hydrogen-278nm, oxygen-205nm, nitrogen-236nm, and carbon-388nm.

11. The detection method of the coaxial dielectric barrier discharge micro-plasma multidimensional element compound detection device according to claim 9, characterized in that, After optical signal acquisition is completed, the gas is discharged from the detection device through the plasma light-collecting window (700).

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