Mass spectrum detection device for free radicals generated by low-temperature plasma discharge

Abstract

The utility model relates to the technical field of mass spectrometric detection, in particular to a mass spectrometric detection device for free radicals generated by low-temperature plasma discharge, which comprises a time-of-flight mass spectrometer, the device comprises a vacuum chamber, a sample introduction rod arranged at the front end of the vacuum chamber, a micro-channel plate arranged at the tail end of the vacuum chamber, and a micro pulse valve and a high-voltage pulse ionization device which are positioned in the vacuum chamber, the gas source is communicated with the front end of the sample introduction rod and is used for receiving input inert carrier gas, and the inert carrier gas and a sample injected through the sample introduction rod are mixed on the sample introduction rod to form mixed gas; the time schedule controller is respectively connected with the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve and is used for synchronously triggering the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve at the same frequency; the ionization efficiency can be improved, and the application range of mass spectrum detection is expanded; the operation complexity and the maintenance cost are reduced, and the repeatability and the accuracy of a detection result are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to mass spectrum detection technical field especially relates to a kind of mass spectrum detection device of low-temperature plasma discharge generation free radical. BACKGROUND

[0002] Free radical refers to atom or molecule with unpaired electron, and these unpaired electrons make free radical have high reactivity, which has important research significance in many fields. Free radical participates in constructing complex molecular framework as active intermediate in chemical reaction, promotes the development of organic synthesis and other fields, and is closely related to the occurrence and development of various diseases of human body. At present, the detection methods of free radical mainly include two categories of spectroscopy and mass spectrometry. Mass spectrometry is an analysis technique for determining the molecular weight and structure of substances by measuring the mass-to-charge ratio of ions, which has the advantages of high sensitivity and high resolution, can detect trace free radical and provide accurate composition information, and is helpful to in-depth study of the properties and reaction mechanism of free radical, and provides strong support for the research and application of related fields.

[0003] The Chinese patent with application number CN202111510058.7 discloses a corona discharge free radical sampling mass spectrometer, which proposes a mass spectrometer combining corona discharge and vacuum ultraviolet photoionization for real-time online detection of free radicals. The core of the device includes a quartz glass tube (with a tungsten discharge needle inside), a double sampling cone structure, a vacuum ultraviolet lamp and a time-of-flight mass spectrometer. Free radicals are generated in a vacuum environment by corona discharge, and then the vacuum ultraviolet lamp is used to ionize the free radicals, avoiding the generation of molecular fragments and directly detecting molecular ions. The defects of this patent technology are: the service life and ionization efficiency of the vacuum ultraviolet lamp may be limited by specific free radical species; in addition, the small design of the sampling cone aperture (50-500 μm) is easy to block, and the gas purity requirement is extremely high, which makes the maintenance difficult in actual application.

[0004] A Chinese patent with the application number CN201310520005.2 discloses a mass spectrometry ionization method and ion source device based on cold plasma jet, which develops an open cold plasma jet ion source suitable for rapid ionization of gas, volatile liquid and solid samples. The device is composed of a discharge gas bottle, a metal / quartz discharge cavity, a high-voltage power supply, etc., and ionization is realized by directly bombarding the sample or mixed sample gas with cold plasma jet. Its defects are: the stability of cold plasma jet is easily affected by environmental factors (such as humidity, air flow disturbance), resulting in poor detection repeatability; the ionization efficiency of non-volatile or heat-sensitive substances is low, and the application range is limited; in addition, the distance (1-100 mm) and angle (0-90°) between the jet and the mass spectrometry cone hole need to be finely adjusted, and the operation parameter optimization is time-consuming, making it difficult to realize fully automated detection. The defects of the patent technology are: the stability of cold plasma jet is easily affected by environmental factors (such as humidity, air flow disturbance), resulting in poor detection repeatability; the ionization efficiency of non-volatile or heat-sensitive substances is low, and the application range is limited; in addition, the distance (1-100 mm) and angle (0-90°) between the jet and the mass spectrometry cone hole need to be finely adjusted, and the operation parameter optimization is time-consuming, making it difficult to realize fully automated detection. Practical new type content

[0005] Therefore, the purpose of the embodiments of the present utility model is to provide a mass spectrometry detection device for generating free radicals by low-temperature plasma discharge, which can expand the application range of mass spectrometry detection, reduce the operation complexity and maintenance cost, and improve the repeatability and accuracy of detection results.

[0006] The embodiments of the present utility model provide a mass spectrometry detection device for generating free radicals by low-temperature plasma discharge, which comprises:

[0007] The time-of-flight mass spectrometer comprises a vacuum chamber, a sample injection rod arranged at the front end of the vacuum chamber, a microchannel plate arranged at the end of the vacuum chamber, and a micro pulse valve and a high-voltage pulse ionization device located inside the vacuum chamber; the microchannel plate is signal connected with a signal processing system; the input end of the micro pulse valve is communicated with the end of the sample injection rod, and the output end is communicated with the high-voltage pulse ionization device;

[0008] A gas source is communicated with the front end of the sample injection rod, used for receiving the input inert carrier gas, and the inert carrier gas is mixed with the sample injected through the front end of the sample injection rod to form a mixed gas in the sample injection rod;

[0009] A timing controller is connected with the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve respectively, and the timing controller is used for synchronously triggering the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve at the same frequency.

[0010] Optionally, the mass spectrometry detection device further comprises an electrode flange arranged at the front end of the vacuum chamber, and the pulse high-voltage power supply is arranged on the electrode flange.

[0011] Optionally, the time sequence controller adopts a three-channel pulse trigger, and the three channels of the pulse trigger are connected with the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve respectively.

[0012] Optionally, the high-voltage pulse ionization device comprises, in sequence and side by side, an acrylic insulating plate, a stainless steel electrode, a polytetrafluoroethylene insulating plate and a copper electrode, and a circular hole channel is arranged through the center of the acrylic insulating plate, the stainless steel electrode, the polytetrafluoroethylene insulating plate and the copper electrode.

[0013] The micro pulse valve is used for spraying the mixed gas in the form of pulses to the ionization area of the high-voltage pulse ionization device.

[0014] The pulse high-voltage power supply is used for providing high-voltage pulses for the stainless steel cathode and the copper anode in the ionization area.

[0015] The vacuum ultraviolet photon source is used for emitting ultraviolet light of a set wavelength, and the light emission direction of the ultraviolet light is perpendicular to the plane of the gas beam injection.

[0016] The micro channel plate is used for receiving and amplifying the signals generated by the ion beam, and the output signals are transmitted to the signal processing system.

[0017] Optionally, the two output channels of the high-voltage pulse power supply are connected with the copper electrode and the stainless steel electrode of the high-voltage pulse ionization device respectively.

[0018] Optionally, the diameter of the acrylic insulating plate is 45 mm, and the thickness is 7 mm; the diameter of the stainless steel electrode is 32 mm, and the thickness is 1.5 mm; the diameter of the polytetrafluoroethylene insulating plate is 32 mm, and the thickness is 2 mm; the maximum diameter of the copper electrode is 32 mm, the minimum diameter is 10 mm, and the thickness is 8 mm.

[0019] Optionally, the diameters of the circular hole channels in the acrylic insulating plate and the stainless steel electrode are both 1 mm; the diameter of the circular hole channel in the polytetrafluoroethylene insulating plate is 3 mm, and the diameter of the circular hole channel in the copper electrode is 1.5 mm.

[0020] Optionally, the micro pulse valve, the acrylic insulating plate, the stainless steel electrode, the polytetrafluoroethylene insulating plate and the copper electrode are fixed by screws made of polyether ether ketone material.

[0021] The utility model embodiment includes following beneficial effect: the mass spectrum detection device that the embodiment provided low temperature plasma discharge generates free radical, through gas source inert carrier gas is input vacuum cavity, inert carrier gas is mixed with the sample injection rod injection in sample injection rod and forms mixed gas, through time sequence control ware with same frequency synchronous trigger pulse high voltage power supply, vacuum ultraviolet photon source and micro pulse valve, makes mixed gas ionize generation free radical in high pressure pulse ionization device, micro channel board receives and amplifies the signal that ion beam produces, signal processing system accurate analysis, significantly improve detection sensitivity and resolution. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will be briefly introduced the drawing needed to be used in the embodiment, obviously, the drawing in the following description only some embodiments of the utility model, for ordinary skilled person in the art, without the premise of creative labor, can also obtain other drawings according to these drawings.

[0023] Figure 1 It is the whole schematic view of mass spectrum detection device that the utility model embodiment provides low temperature plasma discharge generates free radical;

[0024] Figure 2 It is the perspective view of high pressure pulse ionization device provided by the utility model embodiment;

[0025] Figure 3 It is Figure 2 The plan view of high pressure pulse ionization device;

[0026] Figure 4a It is the mass spectrum diagram of detecting sample as ethanol when no pulse high pressure;

[0027] Figure 4b It is the mass spectrum diagram of detecting sample as ethanol when pulse high pressure 900V is used.

[0028] BRIEF DESCRIPTION OF DRAWINGS

[0029] 1, gas source, 2, pulse high-voltage power supply, 3, sample rod, 4, electrode flange, 5, time sequence controller, 6, vacuum ultraviolet photon source, 7, vacuum cavity, 8, micro-channel plate, 9, signal processing system, 10, micro pulse valve, 11, high-voltage pulse ionization device, 12, acrylic insulating plate, 13, stainless steel electrode, 14, polytetrafluoroethylene insulating plate, 15, copper electrode. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the utility model more clear and intelligible, the following will be further described in detail in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0031] It should be noted that the terms "first", "second" and the like in the description, claims and above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0032] In the description of the utility model, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the utility model.

[0033] In the utility model, unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection or communication with each other; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise expressly limited. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0034] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application, and are not intended to limit the present application.

[0036] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to give a full understanding of the embodiments of the present application.

[0037] The technical terms involved in the present application are explained as follows:

[0038] Low-Temperature Plasma (LTP): Low-temperature plasma refers to plasma generated at a relatively low temperature (usually below 1000K). Compared with high-temperature plasma (such as the plasma on the surface of the sun), the electron temperature of low-temperature plasma is higher, but the temperature of heavy particles (such as ions and neutral particles) is lower.

[0039] Radical: Radical refers to an atom or molecule with unpaired electrons, which makes radicals highly reactive. Radicals can be neutral or charged.

[0040] Mass Spectrometry (MS): Mass spectrometry device refers to an instrument for mass spectrometry analysis, including ion source, mass analyzer, detector, vacuum system, data acquisition system and other components.

[0041] Microchannel Plate (MCP): Microchannel plate is a large-area high-spatial-resolution electron multiplication detector with very high time resolution. It is mainly used as a high-performance night vision image intensifier.

[0042] For example, Figure 1 And Figure 2The utility model discloses a kind of mass spectrum detection devices of low-temperature plasma discharge generation free radical, including:

[0043] The time-of-flight mass spectrometer comprises a vacuum chamber, a sample injection rod 3 arranged at the front end of the vacuum chamber, a microchannel plate 8 arranged at the end of the vacuum chamber, and a micro pulse valve 10 and a high-voltage pulse ionization device 11 located inside the vacuum chamber; the microchannel plate 8 is signal-connected with a signal processing system 9; the input end of the micro pulse valve 10 is communicated with the end of the sample injection rod 3, and the output end is communicated with the high-voltage pulse ionization device 11;

[0044] A gas source 1 is communicated with the front end of the sample injection rod 3, and is used to receive an input inert carrier gas 7; the inert carrier gas is mixed with a sample injected through the front end of the sample injection rod 3 to form a mixed gas in the sample injection rod 3;

[0045] A timing controller 5 is connected with the pulse high-voltage power supply 2, the vacuum ultraviolet photon source 6 and the micro pulse valve 10 respectively, and is used to synchronously trigger the pulse high-voltage power supply 2, the vacuum ultraviolet photon source 6 and the micro pulse valve 10 at the same frequency.

[0046] In view of the deficiencies of the prior art, the utility model provides a kind of mass spectrum detection devices of low-temperature plasma discharge generation free radical, and the high-voltage pulse ionization device 11 is arranged after the sample injection rod 3 in the vacuum chamber of time-of-flight mass spectrometer, and the vacuum chamber is in high vacuum state.The copper electrode 15 and stainless steel electrode 13 of high-voltage pulse ionization device 11 are connected with two output channels of pulse high-voltage power supply 2 by wire respectively.The pulse high-voltage power supply 2, the vacuum ultraviolet photon source 6 and the micro pulse valve 10 are connected with three channels of pulse trigger respectively, and provide timing input for the three by pulse trigger.Gas / liquid sample is placed in the sample injection rod 3 of time-of-flight mass spectrometer.

[0047] The related art needs to manually adjust the distance (1 to 100 mm) and angle (0-90°) of the plasma jet and the mass spectrometry cone hole, which is complicated to operate and has poor stability due to environmental humidity / air flow interference; or relies on a double-sampling cone structure, which has high maintenance cost.The utility model adopts timing controller 5 to synchronously trigger pulse high-voltage power supply 2, vacuum ultraviolet photon source 6 and micro pulse valve 10.Nano-second time matching of micro pulse valve 10 jetting and high-voltage discharge can be realized, and gas flow fluctuation is eliminated; the ionization zone is dynamically coupled with the high-vacuum chamber (10 -5 Pa), so as to avoid the interference of gas pressure fluctuation on plasma.

[0048] The application can significantly improve ionization efficiency, provide higher dissociation energy level compared to traditional photoionization technology, effectively ionize high-energy substances that are difficult to dissociate by traditional photoionization, and significantly expand the substance coverage of mass spectrometry detection. Through precise timing control, fully automated detection is realized, greatly reducing the operation complexity and maintenance cost, and improving the repeatability and accuracy of the detection results.

[0049] In some improved embodiments, the mass spectrometry detection device further comprises an electrode flange 4 arranged at the front end of the vacuum chamber, and the pulse high-voltage power supply 2 is arranged on the electrode flange 4.

[0050] In some improved embodiments, the timing controller 5 adopts a three-channel pulse trigger, and the three channels of the pulse trigger are respectively connected with the pulse high-voltage power supply 2, the vacuum ultraviolet photon source 6 and the micro pulse valve 10.

[0051] As shown in Figures 2 to 3 In some improved embodiments, the high-voltage pulse ionization device 11 comprises, in sequence and side by side, an acrylic insulating plate 12, a stainless steel electrode 13, a polytetrafluoroethylene insulating plate 14 and a copper electrode 15; and a circular hole channel is formed through the center of the acrylic insulating plate 12, the stainless steel electrode 13, the polytetrafluoroethylene insulating plate 14 and the copper electrode 15.

[0052] The micro pulse valve 10 is used for spraying the mixed gas in the form of pulses to the ionization area of the high-voltage pulse ionization device 11.

[0053] The pulse high-voltage power supply 2 is used for providing high-voltage pulses for the stainless steel cathode and the copper anode in the ionization area.

[0054] The vacuum ultraviolet photon source 6 is used for emitting ultraviolet light of a set wavelength, and the light emission direction of the ultraviolet light is perpendicular to the gas beam spraying plane.

[0055] The micro channel plate 8 is used for receiving and amplifying the signals generated by the ion beam, and the output signals are transmitted to the signal processing system 9.

[0056] Specifically, the high-voltage pulse ionization device 11 comprises the micro pulse valve 10, the acrylic insulating plate 12, the stainless steel electrode 13, the polytetrafluoroethylene insulating plate 14 and the copper electrode 15, which are sequentially and side by side adhered and fixed.

[0057] The related art adopts tungsten discharge needle and quartz glass tube, and long-term discharge is easy to cause electrode ablation; the metal / quartz discharge cavity is easy to be contaminated in an open environment. The application adopts a stainless steel cathode (resistant to plasma sputtering) and a copper anode (high thermal conductivity) to cooperate, reduce arc corrosion; the acrylic and polytetrafluoroethylene insulating plate 14 are combined to resist high-voltage breakdown (> 5 kV / mm).

[0058] In some improved embodiments, the two output channels of the pulse high-voltage power supply 2 are connected to the copper electrode 15 and the stainless steel electrode 13 of the high-voltage pulse ionization device 11 respectively.

[0059] In some improved embodiments, the acrylic insulating plate 12 has a diameter of 45 mm, a thickness of 7 mm, and a circular hole channel with a diameter of 1 mm in the center;

[0060] The stainless steel electrode 13 has a diameter of 32 mm, a thickness of 1.5 mm, and a circular hole channel with a diameter of 1 mm in the center;

[0061] The polytetrafluoroethylene insulating plate 14 has a diameter of 32 mm, a thickness of 2 mm, and a circular hole channel with a diameter of 3 mm in the center;

[0062] The copper electrode 15 has a maximum diameter of 32 mm, a minimum diameter of 10 mm, a thickness of 8 mm, and a circular hole channel with a diameter of 1.5 mm in the center.

[0063] The diameter of the circular hole channel in the acrylic insulating plate 12 is aligned with the circular hole channel of the stainless steel electrode 13, ensuring consistent gas flow path and improving ionization efficiency; the materials in each layer are tightly fitted to prevent electrical leakage and ensure detection accuracy.

[0064] In some improved embodiments, the micro pulse valve 10, the acrylic insulating plate 12, the stainless steel electrode 13, the polytetrafluoroethylene insulating plate 14, and the copper electrode 15 are fixed by screws made of polyether ether ketone material.

[0065] The working process of the utility model is as follows:

[0066] The liquid ethanol sample is injected through the sample injection rod 3 and then transferred to the vacuum cavity 7 (maintaining a high vacuum state, about 10 -5 Pa). Helium (inert carrier gas) is introduced from the gas source 1 at 3 atm (absolute pressure) and fully mixed with the ethanol vapor in the sample injection rod 3 to form a uniform gaseous mixture.

[0067] The time sequence controller 5 synchronously triggers the following three components at the same frequency (10 Hz):

[0068] The micro pulse valve 10 is used to pulse the mixed gas at supersonic speed to the ionization zone of the high-voltage pulse ionization device 11;

[0069] The pulse high-voltage power supply 2 is used to provide high-voltage pulses (typical parameters: 1 to 2 kV, pulse width 1 to 10 μs) for the double electrodes (stainless steel cathode and copper anode) in the ionization zone;

[0070] Vacuum ultraviolet photon source 6: emit ultraviolet light of a specific wavelength (such as 118 nm), and the light emission direction is perpendicular to the gas beam jet plane. After the mixed gas is sprayed to the ionization zone through the micro pulse valve 10, the transient plasma discharge is generated between the electrodes under the action of the high voltage pulse. The high voltage pulse plasma ionizes the ethanol molecules to generate parent ions, radical ions and other fragment ions; the vacuum ultraviolet light further ionizes the neutral molecules or low-energy ions to enhance the ion yield and reduce fragmentation.

[0071] The generated ion beam is separated by the flight tube, received and amplified by the micro channel plate 8 (MCP). The micro channel plate 8 outputs the signal to the signal processing system 9, records the flight time through the time-to-digital converter, and finally generates the mass spectrum of ethanol. Refer to Figure 4a and Figure 4b .

[0072] The preferred embodiments of the embodiments of the present application are described above with reference to the accompanying drawings, and the scope of the embodiments of the present application is not limited by this. Any modification, equivalent replacement and improvement made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall be within the scope of the embodiments of the present application.

Claims

1. A mass spectrometry apparatus for detecting radicals generated by low temperature plasma discharge, characterized by comprising: The application relates to a time-of-flight mass spectrometer, which comprises a vacuum chamber, a sample injection rod arranged at the front end of the vacuum chamber, a microchannel plate arranged at the tail end of the vacuum chamber, a micro pulse valve and a high-voltage pulse ionization device arranged inside the vacuum chamber, the microchannel plate is connected with a signal processing system, the input end of the micro pulse valve is communicated with the tail end of the sample injection rod, and the output end is communicated with the high-voltage pulse ionization device. A gas source is communicated with the front end of the sample injection rod and used for receiving inputted inert carrier gas, the inert carrier gas is mixed with a sample injected through the front end of the sample injection rod to form mixed gas in the sample injection rod. A timing controller is connected with a pulse high-voltage power supply, a vacuum ultraviolet photon source and the micro pulse valve respectively, and is used for synchronously triggering the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve at the same frequency. The mass spectrometer further comprises an electrode flange arranged at the front end of the vacuum chamber, and the pulse high-voltage power supply is arranged on the electrode flange.

2. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 1, characterized by, The timing controller adopts a three-channel pulse trigger, and the three channels of the pulse trigger are connected with the pulse high-voltage power supply, the vacuum ultraviolet photon source and the micro pulse valve respectively.

3. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 1, characterized by, The high-voltage pulse ionization device comprises acrylic insulating plates, stainless steel electrodes, polytetrafluoroethylene insulating plates and copper electrodes which are sequentially and side by side arranged.

4. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 1, characterized by, The micro pulse valve is used for spraying the mixed gas to the ionization area of the high-voltage pulse ionization device in a pulse form. The pulse high-voltage power supply is used for providing high-voltage pulses for the stainless steel cathode and the copper anode in the ionization area. The vacuum ultraviolet photon source is used for emitting ultraviolet light of a set wavelength, and the light emitting direction of the ultraviolet light is perpendicularly crossed with the gas beam spraying plane. The microchannel plate is used for receiving and amplifying signals generated by the ion beam and outputting the signals to the signal processing system. Two output channels of the pulse high-voltage power supply are connected with the copper electrode and the stainless steel electrode of the high-voltage pulse ionization device respectively.

5. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 4, characterized by The diameter of the acrylic insulating plate is 45 mm, and the thickness is 7 mm; the diameter of the stainless steel electrode is 32 mm, and the thickness is 1.5 mm; the diameter of the polytetrafluoroethylene insulating plate is 32 mm, and the thickness is 2 mm; the maximum diameter of the copper electrode is 32 mm, the minimum diameter is 10 mm, and the thickness is 8 mm.

6. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 4, wherein The diameters of the circular holes in the circular hole channels of the acrylic insulating plate and the stainless steel electrode are both 1 mm; the diameter of the circular hole channel in the polytetrafluoroethylene insulating plate is 3 mm, and the diameter of the circular hole channel in the copper electrode is 1.5 mm.

7. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 6, wherein The micro pulse valve, the acrylic insulating plate, the stainless steel electrode, the polytetrafluoroethylene insulating plate and the copper electrode are fixed by polyether ether ketone screws.

8. The low-temperature plasma discharge generating radical mass spectrometry apparatus according to claim 4, wherein ​

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