A detection system based on atmospheric pressure plasma emission spectroscopy

Abstract

The application discloses a detection system based on atmospheric pressure plasma emission spectrum, belongs to the field of spectrum, and is used for gas detection under atmospheric pressure. The system comprises a microwave excitation source, a microwave mild ionization device connected with the microwave excitation source, a gas sampling system for feeding the to-be-detected gas into the microwave mild ionization device, a spectrum measurement system for collecting and detecting light emission spectrum, and the microwave mild ionization device comprises a plasma generation cavity, a hollow copper column, a copper ring, a hollow quartz tube and a tuning knob. The end of the plasma generation cavity discharging tail gas is provided with a recess, the hollow copper column and the copper ring are arranged in the plasma generation cavity, and the copper ring semi-encapsulates the hollow copper column. The system can generate plasma in an air environment under atmospheric pressure, greatly simplifies a sampling system and reduces the volume of the sampling system.

Description

Technical Field

[0001] This invention relates to a detection system based on atmospheric pressure plasma emission spectroscopy, belonging to the field of spectroscopy. Background Technology

[0002] In the field of spectroscopic analysis, identifying and quantifying atoms or molecules through characteristic emission lines is a common method, offering advantages such as direct spectral reading, high sensitivity, good selectivity, and fast analysis speed. Atoms or molecules can undergo chemical decomposition in plasma, generating a large amount of free radical information, which can be represented in spectral images. The spectral lines of characteristic functional groups of each substance can serve as a "fingerprint" for atomic or molecular identification, and the concentration of the substance can be determined based on the magnitude of the spectral peak intensity. my country has also applied this technology to many spectroscopic detection instruments; however, these instruments are often large, energy-intensive, and have high operating costs.

[0003] In recent years, microwave plasma has attracted increasing attention due to its advantages such as small size, low cost, and real-time performance, making it possible to detect volatile substances in real-time on-site. Currently, plasma emission spectrometry detection devices used for real-time on-site detection of volatile substances require a pure gas environment, such as argon or nitrogen, which are quite demanding and inconvenient for on-site detection. How to achieve discharge detection under atmospheric pressure in an air environment is a problem that urgently needs to be solved in the field of spectroscopic detection and analysis technology. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of large size, high energy consumption and high operating cost of traditional spectroscopic detection instruments, and to provide a detection system based on atmospheric pressure microwave plasma emission spectroscopy, so as to realize the discharge detection of plasma emission spectroscopy detection system under atmospheric pressure.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: A detection system based on atmospheric pressure plasma emission spectrum includes an ionization device 11, a microwave excitation source 12, a gas injection system 13, and a spectral measurement system 14. The microwave excitation source 12 is connected to the ionization device 11 through a coaxial cable 117. The gas injection system 13 is connected to the ionization device 11 through a polytetrafluoroethylene tube and a conversion connector. The spectral measurement system 14 receives the plasma light signal generated by the ionization device 11 through an optical fiber probe.

[0006] The ionization device 11 includes a plasma generating chamber 114, a hollow copper column 112, a copper ring 113, a hollow quartz tube 111, and a tuning knob 115. The plasma generating chamber 114 is a hollow cylinder. One end of the plasma generating chamber 114 receives the gas to be tested introduced by the gas injection system 13, and the other end discharges the tail gas after plasma generation. The end of the plasma generating chamber 114 that discharges the tail gas is provided with a recess 116, which is shaped like a frustum. The axis of the frustum coincides with the axis of the plasma generating chamber 114. The maximum diameter of the bottom surface of the frustum is 9-15 mm, and the minimum diameter of the bottom surface of the frustum is equal to the diameter of the plasma generating chamber 114. The end with the largest diameter of the bottom surface of the frustum is located at the edge of the plasma generating chamber 114.

[0007] The ionization device 11 also includes a microwave receiver 116 and a coaxial cable 117 for receiving signals from the microwave excitation source 12. One end of the coaxial cable 117 is connected to the microwave receiver 116, and the other end is connected to the plasma generating cavity 114. It is used to transmit the microwave signal emitted by the microwave excitation source 12 to the plasma generating cavity 114. The center of the copper ring 113 is located in the extension direction of the coaxial cable 117, and the part that partially encloses the hollow quartz tube 111 is the position for generating plasma.

[0008] The hollow copper column 112 is open at both ends and is hollow tubular, coupled to the plasma generating chamber 114. A semi-annular copper ring 113 is provided between the hollow copper column 112 and the plasma generating chamber 114, that is, the copper ring 113 partially encloses the hollow copper column 112, and the cross-section is C-shaped. The length of the hollow copper column 112 is greater than that of the copper ring 113 and less than or equal to the length of the plasma generating chamber 114. The hollow quartz tube 111 runs through the hollow copper column 112, that is, the copper ring 113 also partially encloses the hollow quartz tube 111, and the two ends of the hollow quartz tube 111 extend out of the two ends of the plasma generating chamber 114, with one end connected to the gas injection system 13.

[0009] The gas injection system 13 includes an intake pump 131 and a gas delivery pipeline 132. The intake pump 131 and the gas delivery pipeline 132 are connected by pipes, conversion connectors and other devices.

[0010] The spectral measurement system 14 includes a spectrometer 141, an optical fiber probe 142, and an optical fiber 143. The optical fiber probe 141 is fixed at a distance of 0.5 to 2 cm from the hollow quartz tube 111 at a vertical position. The opening of the optical fiber probe 142 is directly opposite the hollow quartz tube 111 and is connected to the spectrometer 141 through the optical fiber 143.

[0011] The power of the microwave excitation source 12 is 10-100W.

[0012] By applying the embodiments of the present invention, plasma can be generated in an air environment under atmospheric pressure, and the sample introduction system is greatly simplified and its volume is reduced.

[0013] The beneficial effects of the present invention are as follows: 1. The internal design of the detection system based on atmospheric pressure plasma emission spectrum can increase the internal electric field of microwaves in the plasma generation cavity to 21kV / cm, which is 7 times the breakdown field strength of air, making it simpler and more effective to generate plasma under atmospheric pressure, i.e., in the air environment.

[0014] 2. The detection system based on atmospheric pressure plasma emission spectrum utilizes principles such as standing waves and resonance to generate microwave plasma, and the plasma generation method is simple and efficient.

[0015] 3. The discharge process does not require the intervention of carrier gas, and there is no need for atomization, drying, or other treatments of the analyte, which greatly reduces the overall size of the system and has the advantages of portability, flexibility, on-site operation, and low cost. This invention can directly extract gas from the environment and send it directly into the plasma generation area, greatly reducing processing time and providing the advantages of real-time and continuous operation. Attached Figure Description

[0016] Figure 1 Schematic diagram of the detection system based on atmospheric pressure plasma emission spectroscopy

[0017] In the diagram: 11. Microwave thermal ionization device; 111. Hollow quartz tube; 112. Hollow copper column; 113. Copper ring; 114. Plasma generation chamber; 115. Tuning knob; 1151. First tuning knob; 1152. Second tuning knob; 116. Recess; 117. Coaxial cable; 12. Microwave excitation source; 13. Gas injection system; 131. Gas pump; 132. Gas injection tube; 14. Spectroscopic measurement system; 141. Spectrometer; 142. Fiber optic probe; 143. Fiber optic cable; 15. Coaxial cable.

[0018] Figure 2 Side view of the copper ring section of the microwave mild ionization device

[0019] In the diagram: 112. Hollow copper pillar, 113. Copper ring.

[0020] Figure 3 Front view of the copper ring of the microwave mild ionization device

[0021] In the diagram: 112. Hollow copper column, 113. Copper ring, 15. Coaxial cable.

[0022] Figure 4 Front view of the recessed part of the microwave thermal ionization device

[0023] In the diagram: 111. Hollow quartz tube, 112. Hollow copper column, 114. Plasma generating chamber.

[0024] Figure 5 Cross-sectional view of the recessed portion of the microwave thermal ionization device

[0025] In the diagram: 116. Depression.

[0026] Figure 6 DMMP spectrum based on atmospheric pressure microwave plasma emission spectrum

[0027] In the figure: a is the air spectrum curve, and b is the air + DMMP curve;

[0028] The vertical axis represents spectral intensity in au; the horizontal axis represents wavelength in nm. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described in conjunction with the embodiments and accompanying drawings.

[0030] Example 1

[0031] like Figure 1 As shown, the detection system based on atmospheric pressure plasma emission spectrum includes a microwave excitation source 12, a microwave mild ionization device 11 connected to the microwave excitation source 12, a gas injection system 13 for introducing the gas to be tested into the microwave mild ionization device 11, and a spectral measurement system 14 for acquiring and detecting the emission spectrum; the microwave mild ionization device 11 includes a plasma generating cavity 114, a hollow copper column 112, a copper ring 113, a hollow quartz tube 111, and a tuning knob 115.

[0032] The plasma generating cavity 114 is a hollow cylinder. One end of the plasma generating cavity 114 receives the gas to be tested introduced by the gas injection system 13, and the other end of the plasma generating cavity 114 discharges the tail gas after plasma generation. The end of the plasma generating cavity 114 that discharges the tail gas is provided with a recess 116, which is shaped like a frustum. The axis of the frustum coincides with the axis of the plasma generating cavity 114. The maximum diameter of the bottom surface of the frustum is 9-15 mm, and the minimum diameter of the bottom surface of the frustum is equal to the diameter of the plasma generating cavity 114. The end with the largest diameter of the bottom surface of the frustum is located at the edge of the plasma generating cavity 114. The recess 116 is used to enhance the electric field intensity at the plasma generation point inside the plasma generating cavity 114.

[0033] The hollow copper column 112 is open at both ends and is hollow tubular. The hollow copper column 112 is coupled to the plasma generating chamber 114. A semi-annular copper ring 113 is provided between the hollow copper column 112 and the plasma generating chamber 114, that is, the copper ring 113 partially encloses the hollow copper column 112. The cross-section of the copper ring 113 is C-shaped. The length of the hollow copper column 112 is greater than that of the copper ring 113, and the length of the hollow copper column 112 is less than or equal to the length of the plasma generating chamber 114. The combination of the hollow copper column 112 and the copper ring 113 is used to generate standing wave ionized gas in the plasma generating chamber 114.

[0034] The hollow quartz tube 111 passes through the hollow copper column 112, and the copper ring 113 also partially encloses the hollow quartz tube 111. The two ends of the hollow quartz tube 111 extend to the two ends of the plasma generating chamber 114. One end of the hollow quartz tube 111 is connected to the gas injection system 13, and the other end discharges the tail gas after plasma generation. The plasma is generated in the hollow quartz tube 111.

[0035] The tuning knob 115 is located at the end of the plasma generating chamber 114 where the gas to be tested is introduced. The tuning knob 115 includes a microwave tuning knob 1151 and a second microwave tuning knob 1152. Both the microwave tuning knob 1151 and the second microwave tuning knob 1152 are helical and hollow. The microwave tuning knob 1151, the second microwave tuning knob 1152, and the plasma generating chamber 114 share the same axis. The microwave tuning knob 1151 is used for coarse adjustment to reduce microwave reflection power, and the second microwave tuning knob 1152 is used for fine adjustment to reduce microwave reflection power. The hollow quartz tube 111 passes through the tuning knob 115 and is connected to the gas sample introduction system 13. The microwave warming and ionization device 11 generates plasma at atmospheric pressure.

[0036] The atmospheric pressure plasma emission spectroscopy-based detection system is an emission spectroscopy detection system that can directly detect discharges in air under atmospheric pressure. It consists of several main parts: a microwave excitation source 12, a microwave gentle ionization device 11, a gas sample introduction system 13, and a spectral measurement system 14. The microwave excitation source 12 is connected to the microwave gentle ionization device 11 via a microwave transmission line. When the gas to be tested enters the microwave gentle ionization device 11 through the gas sample introduction system 13, the power supply to the microwave excitation source 12 is activated, generating a non-thermal equilibrium low-temperature plasma in the microwave gentle ionization device 11. The gas to be tested undergoes ionization, splitting, and excitation in the plasma atmosphere. The plasma emission is coupled to the spectral measurement system 14, which monitors and records the emission. Based on the characteristic spectra, i.e., spectral lines and bands, the composition of the gas to be tested is identified, and the content of the gas to be tested is determined based on the spectral intensity.

[0037] In this embodiment, since plasma is generated directly in the air under atmospheric pressure, the aforementioned equipment is omitted. The gas sample introduction system 13 includes an intake pump 131 and a PTFE tube 132. Under atmospheric pressure, the gas to be tested is directly drawn in by the intake pump 131, and then introduced into the microwave warming and ionization device 11 through the PTFE tube 132. Of course, in addition to the PTFE tube 132, other materials can also be used as the gas delivery path. This effectively simplifies the entire plasma emission spectroscopy detection system and reduces its overall size. This provides the possibility of developing a portable plasma emission spectroscopy detection instrument to address the technical problem of real-time on-site detection of volatile substances.

[0038] The spectral measurement system 14 is used to monitor, record, and analyze the plasma generated in the microwave mild ionization device 11. The spectral measurement system 14 may include a spectrometer 141, a fiber optic probe 142, and an optical fiber 143 connecting the spectrometer 141 and the fiber optic probe 142. The spectrometer 141 can be small. The small spectrometer consists of a collimating lens, a focusing lens, a grating entrance slit, and a CCD detector. It should be noted that the fiber optic probe 142 is positioned near the end of the plasma generating cavity 114 venting gas in the microwave mild ionization device 11, which is more conducive to monitoring the emission spectrum emitted by the plasma.

[0039] The microwave mild ionization device 11 generates plasma by ionizing gas in a mild environment, meaning the gas temperature is low when plasma is generated. In this embodiment, the microwave discharge gas temperature is maintained at around 1200K during plasma generation. The main body of the microwave mild ionization device 11 is cylindrical. Along the central axis of the cylindrical microwave mild ionization device 11, a hollow cylindrical plasma generating cavity 114 is provided at the center of the main body. Plasma is generated in the plasma generating cavity 114. One end of the plasma generating cavity 114 receives the gas to be tested introduced by the gas sample introduction system 13, and the other end of the plasma generating cavity 114 discharges the tail gas after plasma generation. At the end of the plasma generating cavity 114 where the tail gas is discharged, i.e., at the outlet of the microwave mild ionization device 11, a recess 116 is provided. The recess 116 enhances the internal electric field generated by microwaves in the plasma generating cavity 114. The recessed portion 116 is integrally formed with the plasma generating cavity 114. The recessed portion 116 is a frustum-shaped structure with its axis horizontal. The bottom surface of the frustum is located inside the plasma generating cavity 114, and the bottom surface of the frustum is located at the edge of the plasma generating cavity 114. The diameter of the bottom surface of the frustum is the largest, and the diameter of the top surface is the smallest. The diameter of the top surface is equal to the diameter of the hollow part of the plasma generating cavity 114, and the axis of the frustum coincides with the axis of the plasma generating cavity 114. The plasma generating cavity 114 and the recessed portion 116 are symmetrically arranged. The coincidence of the axis of the frustum with the axis of the plasma generating cavity 114 is more conducive to enhancing the electric field of microwaves within the plasma generating cavity 114. In this embodiment, the maximum diameter of the bottom surface of the frustum, i.e., the diameter of the bottom surface of the frustum, is 9-15 mm. According to experiments, the electric field inside the microwave can be increased to 21 kV / cm, which is 7 times the breakdown field strength of air.

[0040] A hollow copper column 112 and a copper ring 113 are disposed within the plasma generating cavity 114. The length of the copper ring 113 is much shorter than the length of the hollow copper column 112. The walls of the copper ring 113 are relatively thin, and the copper ring 113 partially encloses the hollow copper column 112, with their axes basically coinciding. The diameter of the hollow copper column 112 is 4 mm, and the diameter of the copper ring 113 is 8 mm. When a microwave signal is transmitted to the plasma generating cavity 114, this structure will cause strong standing waves to be generated in the annular hollow copper column 112 and the copper ring 113, causing the discharge gas in the quartz tube to resonate and generate microwave plasma. Therefore, the combination of the aforementioned recess 116 and the hollow copper column 112 and copper ring 113 together rapidly enhances the electric field inside the plasma generating cavity 114 in a short time. When the igniter is activated, microwave plasma will be generated in the air even under atmospheric pressure.

[0041] A hollow quartz tube 111 runs through the entire microwave gentle ionization device 11, and microwave plasma is generated within the hollow quartz tube 111. Inside the plasma generation chamber 114, the hollow quartz tube 111 runs through a hollow copper column 112 and is also partially enclosed by a copper ring 113. When the microwave excitation source 12 is activated, the portion of the hollow quartz tube 111 partially enclosed by the copper ring 113 is the area with the strongest electric field within the microwave gentle ionization device 11, i.e., this is where plasma is generated. The gas injection system 13 introduces the gas to be tested into the hollow quartz tube 111 through a PTFE tube. The inner diameter of the hollow quartz tube 111 is 1.5 mm, and the outer diameter is 3 mm. Of course, other quartz glass tubes with different structural parameters can also be used, and other sizes and types of materials can be selected as the jet tube; no limitations are imposed here.

[0042] The tuning knob 115 is a double-helix tuning knob. It is used to adjust the reflected power of the microwaves generated within the plasma generating chamber 114. Therefore, the tuning knob 115 is located at the end of the plasma generating chamber 114 where the gas to be measured is introduced. The microwave tuning knob 1151, the second microwave tuning knob 1152, and the plasma generating chamber 114 share the same axis. The microwave tuning knob 1151 can be adjusted over a wide range of reflected power. After the microwave tuning knob 1151 is adjusted to the optimal position, the second microwave tuning knob 1152 is adjusted to minimize the reflected power.

[0043] The microwave mild ionization device 11 also includes a microwave receiver 116 and a coaxial cable 117 for receiving signals from the microwave excitation source 12. One end of the coaxial cable 117 is connected to the microwave receiver 116, and the other end of the coaxial cable 117 is connected to the plasma generating cavity 114. The coaxial cable 117 is used to transmit the microwave signal emitted by the microwave excitation source 12 to the plasma generating cavity 114. The center of the copper ring 113 is located in the extension direction of the coaxial cable 117, and the part of the copper ring 113 that partially encloses the hollow quartz tube 111 is the position where plasma is generated.

[0044] The microwave receiver 116 is disposed on the side wall of the microwave gentle ionization device 11 body, or on the upper part of the microwave gentle ionization device 11 body, or horizontally disposed on the microwave gentle ionization device 11 body, but it should be disposed at the end near the recessed portion 116, which is more conducive to generating a strong electric field ionized gas locally within the plasma generating cavity 114. The microwave signal can be transmitted in the microwave gentle ionization device 11 via a coaxial cable 117, or other microwave signal transmission lines, which are not limited here.

[0045] The microwave receiver 116 can also be positioned above the main body of the microwave warming and ionization device 11, near one end of the recess 116. A coaxial cable 117 is vertically positioned between the microwave receiver 116 and the plasma generating cavity 114. When the microwave signal is transmitted from the microwave excitation source 12 to the plasma generating cavity 114, the connection point between the coaxial cable 117 and the plasma generating cavity 114 is where the plasma generating cavity 114 receives the strongest microwave signal. Therefore, the center of the central axis of the copper ring 113 can be approximately positioned on the extension line of the coaxial cable 117 extending towards the plasma generating cavity 114, i.e., directly below the coaxial cable 117. This design is beneficial for enhancing the internal electric field generated by the microwave. Simultaneously, the location where plasma is generated inside the hollow quartz tube 111 is precisely the part of the hollow quartz tube 111 enclosed by the copper ring 113.

[0046] The power of the microwave excitation source 12 is 10-100W.

[0047] Since this embodiment has a recessed portion 116 at the outlet of the plasma generating cavity 114, and a hollow copper column 112 and a copper ring 113 in the plasma generating cavity 114, the above designs can enhance the internal electric field strength at the plasma generation point. Therefore, the power of the microwave excitation source 12 does not need to be too large. A power range of 10 to 100W is sufficient to generate microwave plasma at atmospheric pressure.

[0048] The test uses a chemical agent gas as the gas to be tested. In this embodiment, DMMP (dimethyl methanephosphonate), a sarin simulant, is selected as the gas to be tested. The specific operating steps are as follows:

[0049] First, turn on the microwave excitation source 12 and set its power parameter to 100W. The microwave is introduced into the plasma generating cavity 114 through the microwave transmission line and ignited with an igniter to generate microwave plasma. After the microwave plasma is generated, adjust the tuning knob to make its reflection power reach the minimum.

[0050] The plasma generated at this time is microwave plasma produced by the direct ionization of air.

[0051] Turn on the suction pump 131 to introduce the test gas containing DMMP into the hollow quartz tube 111.

[0052] Finally, the fiber optic probe 142 was fixed in place to ensure accurate monitoring and recording of plasma information. The captured spectral information was recorded using Morpho 3.2 software (developed by Shanghai Fuxiang Optics Co., Ltd.) provided with the spectrometer 141.

[0053] Because the microwave gentle ionization device 11 has a recess 116 at its outlet, the local electric field can be enhanced. Under microwave resonant excitation mode, after the microwave excitation source 12 is turned on, the microwave is coupled into the plasma generating cavity 114 through the microwave conduction line. Under the action of the hollow copper column 112 and the copper ring 113, a strong standing wave will be formed when the microwave reaches the resonance condition. After being ignited by an igniter, microwave plasma is generated in the hollow quartz tube 111.

[0054] The suction pump 131 used in the experiment directly extracts gas from the environment and sends it directly into the hollow quartz tube 111, which greatly reduces the processing time and has real-time and continuous operation.

[0055] Without the introduction of DMMP, the plasma appears as a pure bright white, which is simply plasma generated by ionizing air. After the introduction of DMMP, the high-energy electrons in the plasma collide with DMMP molecules, causing them to break down into a large number of free radicals. The plasma color changes to light blue, and the characteristic DMMP spectral lines can be detected in the spectrum.

[0056] like Figure 2 As shown in the atmospheric pressure microwave-based DMMP spectrum provided in this embodiment of the invention, the spectrometer detected the P atom spectral line and the PO molecular band. When DMMP is ionized by microwaves, the chemical bonds of phosphides such as CH3-P and P-OCH3 in DMMP break in the plasma, generating P atoms and PO groups. Phosphides can be identified based on the generated P atoms and PO groups. As can be seen from the measured spectrum, the characteristic emission lines of P atoms at 213.82 nm and 215.09 nm, and the characteristic emission lines of PO groups at 253.67 nm and 255.6 nm can be observed. Phosphides can be identified by these spectral lines.

[0057] By applying the embodiments of the present invention, the gas to be tested in the atmospheric pressure environment can be directly sent into the plasma region. During on-site environmental testing, there is no need to use a complex sample introduction system, which saves a lot of space for the detection device. At the same time, discharge detection can be performed in the air environment without the need to use pure gases such as argon and nitrogen. This not only meets the atmospheric pressure air environment of on-site surveys, but also saves costs and has strong sustainability. The device is more convenient, portable, and has better real-time performance.

Claims

1. A detection system based on atmospheric pressure plasma emission spectroscopy, characterized in that, The detection system includes an ionization device (11), a microwave excitation source (12), a gas injection system (13), and a spectral measurement system (14). The microwave excitation source (12) is connected to the ionization device (11) via a coaxial cable (117). The gas injection system (13) is connected to the ionization device (11) via a polytetrafluoroethylene tube and a conversion connector. The spectral measurement system (14) receives the plasma light signal generated by the ionization device (11) via an optical fiber probe. The ionization device (11) includes a plasma generating chamber (114), a hollow copper column (112), a copper ring (113), a hollow quartz tube (111), and a tuning knob (115). The plasma generating chamber (114) is a hollow cylinder. One end of the plasma generating chamber (114) receives the gas to be tested introduced by the gas injection system (13), and the other end discharges the tail gas after plasma generation. The end of the plasma generating chamber (114) that discharges the tail gas is provided with a recess (116). The recess (116) is in the shape of a frustum. The axis of the frustum coincides with the axis of the plasma generating chamber (114). The maximum diameter of the bottom surface of the frustum is 9-15 mm, and the minimum diameter of the bottom surface of the frustum is equal to the diameter of the plasma generating chamber (114). The end with the largest diameter of the bottom surface of the frustum is located at the edge of the plasma generating chamber (114). The ionization device (11) also includes a microwave receiver (116) and a coaxial cable (117) for receiving signals from the microwave excitation source (12). One end of the coaxial cable (117) is connected to the microwave receiver (116), and the other end is connected to the plasma generating cavity (114). It is used to transmit the microwave signal emitted by the microwave excitation source (12) to the plasma generating cavity (114). The center of the copper ring (113) is located in the extension direction of the coaxial cable (117), and the part that partially wraps the hollow quartz tube (111) is the position for generating plasma. The hollow copper column (112) is open at both ends and is hollow tubular, coupled to the plasma generating chamber (114). A semi-annular copper ring (113) is provided between the hollow copper column (112) and the plasma generating chamber (114), that is, the copper ring (113) partially encloses the hollow copper column (112), and the cross-section is C-shaped. The length of the hollow copper column (112) is greater than that of the copper ring (113) and less than or equal to the length of the plasma generating chamber (114). The hollow quartz tube (111) runs through the hollow copper column (112), that is, the copper ring (113) also partially encloses the hollow quartz tube (111), and the two ends of the hollow quartz tube (111) extend out of the two ends of the plasma generating chamber (114), with one end connected to the gas injection system (13). The gas injection system (13) includes an intake pump (131) and a gas delivery pipeline (132). The intake pump (131) and the gas delivery pipeline (132) are connected by pipelines, conversion connectors and other devices. The spectral measurement system (14) includes a spectrometer (141), an optical fiber probe (142), and an optical fiber (143). The optical fiber probe (142) is fixed at a distance of 0.5cm to 2cm from the hollow quartz tube (111) at a vertical position. The opening of the optical fiber probe (142) is directly opposite the hollow quartz tube (111), and it is connected to the spectrometer (141) through the optical fiber (143).

2. The detection system based on atmospheric pressure plasma emission spectroscopy according to claim 1, characterized in that, The power of the microwave excitation source (12) is 10-100W.

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