Method and system for detecting types and concentrations of plasma products

Abstract

The invention discloses a method and system for detecting the type and concentration of plasma products, and belongs to the technical field of plasmas, and the method comprises the steps: obtaining a space temperature distribution diagram in a plasma reaction cavity at different moments under different discharge voltages based on the collected real-time temperature when plasma is generated; the method comprises the following steps: acquiring types and particle number density of plasma main products under a short time scale by simulating a discharge process in a plasma reaction cavity; and on the basis of the temperature distribution diagram and the discharge area during plasma generation, according to the particle number density, obtaining the generation rate of each product and the substance concentration change in the plasma reaction cavity under the long time scale. According to the method, plasma product mode discrimination and product concentration detection under a long time scale are realized, the influence of a real-time discharge area and a temperature field on product concentration calculation is comprehensively considered, the detection process is simple and convenient, and a guarantee is provided for efficient operation of plasmas in industrial application.

Description

Technical Field

[0001] The present invention relates to the field of plasma technology, and in particular to a method and system for detecting types and concentrations of plasma products. Background Art

[0002] Atmospheric pressure low-temperature plasma is usually produced under open air conditions by a device consisting of a high-voltage electrode and a ground electrode. It has a simple structure, uniform and stable discharge, a large active area, and abundant active particles. It is widely used in biomedicine, aerospace, material modification, food preservation and other fields.

[0003] The plasma product modes include O3 mode under lower power conditions and NO mode under higher power conditions. x Mode and the transition mode between the two. Under different product modes, the types and concentration distributions of active particles (such as high-energy electrons, photons, excited molecules, atoms and ozone, etc.) generated by plasma vary greatly, which plays a decisive role in its application effect. Therefore, in the practical application of plasma, how to simply and quickly identify its product mode and calculate its product concentration is a crucial issue.

[0004] In existing research, the identification of plasma product patterns is mostly based on the detection of its products and electrical properties, while the detection of product types and concentrations requires the construction of a specific detection platform or the design of a special calculation model. These methods often have disadvantages such as high detection costs, complex detection methods, poor consistency between calculation results and actual results, and long time consumption. For example, Fourier transform infrared spectrometer (FITR) and ozone or nitrogen oxide detectors are commonly used methods for laboratories to determine plasma product patterns and measure product concentrations, but FITR is expensive, and the measurement system usually requires additional customization of an absorption cell equipped with an infrared window. Ozone or nitrogen oxide detectors need to be connected to the entire system, and the response time and accuracy of the instrument depend on the cost of the equipment.

[0005] At present, most simulation models for plasma product concentration do not consider the coupling of temperature field or define temperature field too simply, and their calculation results are generally on a short time scale (ns-μs level). The simulation results cannot accurately reflect the effect of fluid heat transfer on particle concentration on a long time scale, resulting in a large difference between the simulation results and the actual results. Therefore, the development of a long-time scale plasma product type and concentration detection technology that does not rely on gas phase product detection and couples plasma-temperature-chemical reaction multi-physics fields is an urgent problem to be solved to accelerate the industrial application of plasma. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a low-cost and simplified detection technology for the types and concentrations of plasma products. A temperature acquisition module is used to collect the real-time temperature of the electrode and input an external voltage. The reaction rate and particle number density of the main products of the plasma on a long time scale are calculated through the coupling of a temperature simulation module, a plasma simulation module and a chemical reaction simulation module, thereby realizing the calculation of the types and concentrations of plasma products.

[0007] In order to achieve the above technical objectives, the present application provides a method for detecting the type and concentration of plasma products, comprising the following steps:

[0008] Based on the collected real-time temperature when the plasma is generated, a spatial temperature distribution diagram inside the plasma reaction chamber at different discharge voltages at different times is obtained;

[0009] By simulating the discharge process in the plasma reaction chamber, the types and particle number density of the main plasma products on a short time scale are obtained;

[0010] Based on the temperature distribution diagram and the discharge area when plasma is generated, the generation rate of each product and the change of substance concentration inside the plasma reaction chamber on a long time scale are obtained according to the particle number density.

[0011] Preferably, in the process of obtaining the real-time temperature, a high voltage is selected as the excitation power supply to stimulate the generation of plasma, and the gas breakdown near the ground electrode generates plasma. The real-time temperature of the ground electrode and the change in the center temperature of the ground electrode after the plasma is generated are obtained as the initial temperature of the calculation input.

[0012] Preferably, in the process of obtaining the temperature distribution diagram, the center temperature of the ground electrode is used as the heat source, and on the basis of considering the heat exchange with the outside air, the spatial temperature distribution diagram inside the plasma reaction chamber at different discharge voltages at different times is obtained, wherein the heat exchange with the outside air includes two parts, one part is transmitted from the ground electrode to the dielectric sheet, and the other part is the heat exchange between the air inside the cavity and the outside through the cavity wall.

[0013] Preferably, in the process of obtaining heat exchange with the outside air, the heat transfer mode between the ground electrode and the dielectric sheet above after heating is heat conduction, and its thermodynamic equation is as follows:

[0014]

[0015] The heat transfer between the ground electrode and the gas below is thermal convection, and its thermodynamic equation is expressed as:

[0016] There is heat convection between the cavity and the outside air, and its thermodynamic equation is expressed as:

[0017] -n·q=q0;q0=h(T ext -T0);

[0018] Where q is the heat of thermal conduction; q0 is the heat of thermal convection; Q ted is the initial heat source, which is 0; k is the solid heat transfer coefficient; h is the air heat transfer coefficient; ν g is the flow rate of gas during natural convection; ρ is the density of gas; C ρ is the constant pressure specific heat capacity of air; T g is the gas temperature rise; T s is the electrode temperature rise; A s is the comprehensive heat transfer coefficient of the electrode; T0 is the room temperature; T ext is the temperature at the interface between the cavity and the air.

[0019] Preferably, in the discharge process in the simulated plasma reaction chamber, it is assumed that only N2, O2 and water vapor exist in the air, the water vapor accounts for 0.03%, the volume ratio of N2 to O2 is 4:1, and the initial number density of each charged particle is 10 13 m -3 ; Simplify the discharge simulation process in the plasma reaction chamber to obtain the types and particle number densities of the main plasma products within a discharge cycle.

[0020] Preferably, in the process of acquiring the discharge area, the actual discharge area is converted and calculated according to the RGB component information of the discharge image, so as to acquire the discharge area when the plasma is generated.

[0021] Preferably, in the process of obtaining the generation rate of each product and the change of substance concentration inside the plasma reaction chamber on a long time scale, the addition rate of each substance per unit volume in each cycle is obtained according to the discharge area and the particle number density of the main plasma products in one discharge cycle, and then the concentration of the product is obtained, wherein the change of substance concentration in the reaction chamber is obtained through zero-dimensional chemical reaction simulation.

[0022] The present invention discloses a system for detecting the type and concentration of plasma products, which is used to implement the above-mentioned method for detecting the type and concentration of plasma products. The system comprises:

[0023] The electrode temperature acquisition module is used to measure and collect the center temperature of the grounding electrode;

[0024] The power drive module is used to provide high voltage as an excitation power source to stimulate the generation of plasma;

[0025] Temperature simulation module, used to obtain the thermodynamic distribution of the internal area of ​​the plasma reaction chamber;

[0026] Plasma simulation module, used to simulate the discharge process in the plasma reaction chamber, and realize the types and particle number density of the main products of short-time scale plasma;

[0027] An image recognition and calculation module is used to realize discharge image recognition and discharge area calculation, wherein the actual discharge area is calculated by collecting discharge image information and converting it according to the RGB component information of the discharge image;

[0028] The chemical reaction simulation module is used to calculate the generation rate and concentration of various products inside the plasma reaction chamber on a long time scale.

[0029] The present invention discloses the following technical effects:

[0030] The present invention realizes the multi-field simulation model of coupled temperature-plasma-chemical reaction by integrally constructing a temperature simulation module, a plasma simulation module and a chemical reaction simulation module to realize the plasma product pattern discrimination and product concentration calculation detection on a long time scale. This technology does not require the use of expensive and complex detection instruments, and comprehensively considers the influence of real-time discharge area and temperature field on product concentration calculation. The detection process is simple and convenient, providing guarantee for the efficient operation of plasma in industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a logical diagram of the calculation of the types of plasma products and their concentrations according to the present invention;

[0033] Figure 2 The relationship between the electrode center temperature and time of the Al2O3-1mm dielectric sheet of the present invention under four discharge voltages;

[0034] Figure 3 The temperature distribution of each area in the cavity of the Al2O3-1mm dielectric sheet of the present invention in each mode for 10 minutes is (a) 2.5kV, O3 mode, (b) 3.75kV, transition mode, (c) 4.5kV, transition mode, (d) 6kV, NOx mode;

[0035] Figure 4The simulation results of the number density of the main products in the plasma region of the Al2O3-1mm dielectric sheet described in the present invention in one discharge cycle are (a) 2.5kV, O3 mode, 20℃, (b) 3.75kV, transition mode, 32℃, (c) 4.5kV, transition mode, 50℃, (d) 6kV, NO x mode, 80°C;

[0036] Figure 5 is the generation rate of the main plasma products at different temperatures described in the present invention;

[0037] Figure 6 The simulation results of the long-time product concentration variation of the Al2O3-1mm dielectric sheet described in the present invention are (a1) 2.5kV, O3 mode, (a2) 6kV, NOx mode, and the measurement results (b1) 2.5kV, O3 mode, (b2) 6kV, NOx mode;

[0038] Figure 7 The simulation results of the long-term product concentration variation of the Al2O3-0.5mm dielectric sheet described in the present invention are (a) 2kV, O3 mode, (b) 4.25kV, NO x model;

[0039] Figure 8 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0040] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0041] like Figure 1-8 As shown, the present invention provides a low-cost and simplified detection technology for the types and concentrations of plasma products, such as Figure 1 As shown, the present invention calculates the reaction rate and particle number density of the main plasma products on a long time scale by coupling the temperature simulation module, the plasma simulation module and the chemical reaction simulation module, and realizes the calculation of the types and concentrations of plasma products, which specifically includes the following contents:

[0042] Step 1: The electrode temperature acquisition module is used to measure and collect the center temperature of the ground electrode. It can be in various forms such as an infrared camera, a temperature gun, a temperature sensor, etc.

[0043] The power drive module is used to provide high voltage as an excitation power supply to stimulate the generation of plasma. It can be a high-voltage DC power supply, a high-voltage AC power supply, a high-voltage pulse power supply, and other types.

[0044] The voltage is input through the power drive module, and the gas near the ground electrode breaks down to generate plasma. Due to the Joule heat effect, the temperature of the ground electrode increases.

[0045] The electrode temperature acquisition module is used to record the initial temperature of the ground electrode and the change in the center temperature of the ground electrode after plasma is generated, and the electrode center temperature-time curve is drawn.

[0046] Step 2: The temperature simulation module is used to calculate the thermodynamic distribution of the internal area of ​​the plasma reaction chamber using a fluid heat transfer model.

[0047] The center temperature of the ground electrode collected by the electrode temperature acquisition module is used as the heat source. The heat is mainly diffused inside the cavity, and heat exchange is formed inside and outside the cavity due to the temperature difference.

[0048] The heat exchange with the outside air is mainly divided into two parts. One part is transferred from the ground electrode to the dielectric sheet, and the other part is the heat exchange between the air inside the cavity and the outside through the cavity wall. After heating, the main heat transfer method between the ground electrode and the dielectric sheet above is heat conduction, and its thermodynamic equation is shown in formula (1). The main heat transfer method between the ground electrode and the gas below is heat convection, and its thermodynamic equation is shown in formula (2). In addition, there is heat convection between the cavity and the outside air, and its thermodynamic equation is shown in formula (3)-formula (4).

[0049]

[0050] -n·q=q0 (3)

[0051] q0=h(T ext -T0) (4)

[0052] Where q is the heat of thermal conduction; q0 is the heat of thermal convection; Q ted is the initial heat source, which is 0; k is the solid heat transfer coefficient; h is the air heat transfer coefficient; ν g is the flow rate of gas during natural convection; ρ is the density of gas, which is 1.29 kg / m 3 ; C ρ is the constant pressure specific heat capacity of air, which is 1 kJ / (kg·℃); T g is the gas temperature rise; T s is the electrode temperature rise; As is the comprehensive heat transfer coefficient of the electrode; T0 is the room temperature, which is 20℃; T ext It is the temperature at the interface between the cavity and the air, which changes in real time.

[0053] According to the above steps, the temperature distribution diagram inside the plasma reaction chamber at different times under the discharge voltage can be obtained.

[0054] Step three: The plasma simulation module is used to simulate the discharge process in the plasma reaction chamber and calculate the particle number density of the main plasma products on a short time scale.

[0055] A two-dimensional plasma model is established, and the simulation time is one cycle.

[0056] Air plasma reactions involve many types of particles and reactions. To simplify the model, it is assumed that there are only N2, O2 and water vapor in the air, with water vapor accounting for 0.03%, the volume ratio of N2 to O2 being 4:1, and the initial number density of each charged particle being 10 13 m- 3 The selected reaction equations and corresponding reaction rates are shown in Table 1.

[0057] Calculate the number density of the main products in one discharge cycle.

[0058] Step 4: The image recognition and calculation module is used to realize discharge image recognition and discharge area calculation:

[0059] The discharge image acquisition device is used to acquire discharge image information, and can be a variety of devices such as a digital camera and an ICCD;

[0060] The image recognition and calculation module extracts the RGB component information of the collected discharge image and converts and calculates the actual discharge area.

[0061] Step 5: The chemical reaction simulation module is used to calculate the generation rate of each product inside the plasma reaction chamber on a long time scale:

[0062] The plasma simulation module only calculates the number density of each particle in the ground electrode surface area within one discharge cycle, but the actual discharge time lasts up to the order of minutes. Within one cycle, the plasma products will quickly diffuse to the entire plasma reaction chamber. Assuming that the initial plasma parameters remain unchanged during each discharge cycle simulation, the addition rate of each substance per unit volume in each cycle can be calculated. The calculation formula is:

[0063] C i =1000000fA2d2V m N i / NA / V (5)

[0064] Among them Ci is the product addition rate (ppm / s), A2 and d2 are the actual discharge area and air gap distance, respectively. m is the molar volume of gas at room temperature, which is 24.5 L·mol- 1 . N i is the number density of the substance. A is Avogadro's constant, which is 6.02×10 23 mol -1 V is the volume of the reaction chamber, which is 5×10 4 mm 3 . f is the discharge frequency, which is 8kHz.

[0065] Assuming that the products diffuse uniformly from the electrode surface to the interior of the plasma reaction chamber over a period of time, the concentration increase rate of long-lived particles in the products can be calculated, and this can be used as the initial generation rate of each related substance. The reaction between the substances under long-term conditions can be calculated, and the concentration of the products can be obtained.

[0066] The chemical reaction simulation is coupled with the temperature simulation of the fluid inside the plasma reaction chamber. Assuming that each substance will diffuse evenly inside the chamber over a long time scale, a zero-dimensional chemical reaction simulation is performed through the chemical reaction simulation module, and the change in substance concentration in the reaction chamber can be calculated.

[0067] Example 1: Simulation calculation of product concentration inside the plasma reaction chamber of an Al2O3-1mm dielectric sheet.

[0068] Use an infrared temperature measuring gun to collect the temperature of the center of the ground electrode when the Al2O3-1mm dielectric sheet discharge voltage is 2.5kV, 3.75kV, 4.5kV, and 6kV, and the discharge lasts for 10 minutes, including the initial temperature before discharge, to obtain the corresponding dielectric sheet thickness and the relationship between the change of the electrode center temperature with time under voltage, such as Figure 2 , as shown. Among them, the product modes corresponding to the four discharge voltages selected under this condition are O3 mode, transition mode, transition mode, NO x model.

[0069] Considering the ground electrode as a heat source, thermal convection will be formed inside the cavity. There is heat exchange between the edge area and the outside of the cavity, and the edge area dissipates more heat. The thermal convection effect in the gas area is obvious, and the temperature in the gas area tends to be the same. The gas temperature drops rapidly compared to the temperature in the electrode area. The bottom edge of the plasma reaction chamber is only a few degrees higher than the room temperature, that is, the plasma reaction is mainly concentrated near the ground electrode. The reaction chamber mainly carries out heat diffusion and long-time scale chemical reactions. It can be calculated that the isothermal distribution of each area in the reaction chamber when the discharge lasts for 10 minutes under this condition is as follows: Figure 3 .

[0070] The ground electrode uses a mesh structure and is located between the dielectric sheet and the gas. The thickness of the dielectric sheet is 1 mm. Assuming that the product of each mesh is the same, a mesh in the ground electrode and its air are selected as the plasma simulation range. The total length of the mesh is 0.6 mm, and the surface air thickness is 0.4 mm. A two-dimensional plasma model is established, and the simulation time is one cycle (125 μs).

[0071] To simplify the model, it is assumed that there are only N2, O2 and water vapor in the air, the water vapor accounts for 0.03%, the volume ratio of N2 and O2 is 4:1, and the initial number density of each charged particle is 10 13 m -3 The selected reaction equations and corresponding reaction rates are shown in Table 1. Different temperatures will lead to different plasma reaction rates, resulting in different number densities of the main particles. The three reactions that vary greatly with temperature are shown in Table 2, of which the first two reactions are reversible reactions. The plasma simulation module program is run to calculate the number density of the main products in the plasma area of ​​the Al2O3-1mm dielectric sheet in one discharge cycle, as shown in Figure 4 .

[0072] Table 1 Chemical reaction formulas involved in one plasma discharge cycle

[0073]

[0074]

[0075] Table 2 Plasma reactions that are greatly affected by temperature and their corresponding reaction rates

[0076] temperature <![CDATA[O2+O2+O→O3+O2]]> <![CDATA[O3+O2→O2+O2+O]]> <![CDATA[O3+O→O2+O2]]> 20℃ <![CDATA[3.31×10 -10 ]]> <![CDATA[7.04×10 -11 ]]> <![CDATA[8.81×10 -11 ]]> 30℃ <![CDATA[2.68×10 -10 ]]> <![CDATA[1.45×10 -10 ]]> <![CDATA[1.15×10 -10 ]]> 40℃ <![CDATA[2.09×10 -10 ]]> <![CDATA[2.71×10 -10 ]]> <![CDATA[1.41×10 -10 ]]> 50℃ <![CDATA[1.60×10 -10 ]]> <![CDATA[4.87×10 -10 ]]> <![CDATA[1.76×10 -10 ]]> 60℃ <![CDATA[1.26×10 -10 ]]> <![CDATA[8.84×10 -10 ]]> <![CDATA[2.22×10 -10 ]]> 70℃ <![CDATA[1.03×10 -10 ]]> <![CDATA[1.57×10 -9 ]]> <![CDATA[2.78×10 -10 <!-- 6 -->]]> 80℃ <![CDATA[9.60×10 -11 ]]> <![CDATA[2.24×10 -9 ]]> <![CDATA[3.29×10 -10 ]]>

[0077] The calculation area of ​​the plasma simulation module is just one of the meshes. It is assumed that the particles in each mesh are evenly distributed and diffuse evenly into the reaction chamber below. After the particles generated in one cycle diffuse into the air area in the chamber, the initial particle density in the plasma area increases from 10 13 m -3 Restart. The generation rate can be calculated by formula (5) based on the number density at the end of the discharge cycle (125μs) and used as the addition rate of the chemical reaction simulation module. Figure 5 is the generation rate of each main product at different temperatures. It can be seen from formula (5) that, when the plasma generating device and discharge frequency are given, the addition rate of each main product is proportional to its number density.

[0078] The chemical reaction simulation module is based on the addition concentration of the main products, combined with Figure 3 The distribution of the temperature in the reaction chamber and Figure 5The converted addition rate is used to calculate the reaction between the substances under long-term conditions, and then the concentration of the product is obtained. Figure 6 (a1), (a2). Figure 6 (b1) and (b2) are the O3 mode and NO mode measured by Fourier transform infrared spectrometer under the same conditions. x By comparing the variation pattern of product concentration over time under the model, it can be seen that the variation pattern of product concentration over time calculated by the patented model is highly consistent with the results of experimental measurements.

[0079] Table 3 Chemical reaction formulas involved in the diffusion of long-lived particles

[0080] Serial number Reaction equation <![CDATA[Reaction rate (cm 3 s -1 )]]> 1 N+O→NO <![CDATA[3.78×10 -16 ×T g 0.75 ]]> 2 <![CDATA[O+N2→NO+N]]> <![CDATA[3.01×10 -10 / T g ]]> 3 <![CDATA[NO+O→NO2]]> <![CDATA[4.20×10 -13 ×T g 0.75 ]]> 4 <![CDATA[NO2+OH→HNO3]]> <![CDATA[1.19×10 -8 / T g ]]> 5 <![CDATA[NO+O3→NO2+O2]]> <![CDATA[1.80×10 -18 ×T g 3.25 ]]> 6 <![CDATA[N2→N+N]]> <![CDATA[8.19×10 -18 ]]> 7 <![CDATA[O2→O+O]]> <![CDATA[8.31×10 -20 ]]> 8 <![CDATA[O2+O2+O→O2+O3]]> <![CDATA[3.58×10 -8 / T g ]]> 9 <![CDATA[N+NO2→N2O+O]]> <![CDATA[5.8×10 -18 ×T g 0.65 ]]> 10 <![CDATA[O3→O2+O]]> <![CDATA[3.92×10 -16 ×exp(-1140 / T g )]]> 11 <![CDATA[N+O3→O2+NO]]> <![CDATA[2.01×10 -16 ]]>

[0081] Embodiment 2:

[0082] Simulation calculation of product concentration inside the plasma reaction chamber of Al2O3-0.5mm dielectric sheet.

[0083] An infrared temperature measuring gun is used to collect the temperature of the center of the grounding electrode when the discharge voltage of the Al2O3-0.5mm dielectric sheet is 2kV, 2.88kV, 3.25kV, and 4.25kV, and the discharge lasts for 10 minutes, including the initial temperature before discharge, to obtain the corresponding relationship between the dielectric sheet thickness and the change of the electrode center temperature over time under voltage.

[0084] The ground electrode is regarded as a heat source, and the isothermal distribution of each area in the reaction chamber when the discharge lasts for 10 minutes under this condition can be obtained by calculation using the method described in Example 1.

[0085] The ground electrode uses a mesh structure and is located between the dielectric sheet and the gas. The thickness of the dielectric sheet is 1 mm. Other conditions are as described in Example 1. A two-dimensional plasma model is established, and the simulation time is one cycle (125 μs). The plasma simulation module program is run to calculate the number density of the main products in the plasma region of the Al2O3-0.5 mm dielectric sheet in one discharge cycle.

[0086] The chemical reaction simulation module is as described in Example 1, and calculates the reaction between the substances under long-term conditions, and then obtains the concentration of the Al2O3-0.5mm dielectric sheet product as follows: Figure 7 .

[0087] The present invention realizes the plasma product pattern identification and product concentration calculation on a long time scale by using a multi-field simulation model of coupled temperature-plasma-chemical reaction that is integrally constructed through a temperature simulation module, a plasma simulation module and a chemical reaction simulation module. The method does not require the use of expensive and complex detection instruments, and comprehensively considers the influence of the real-time discharge area and the temperature field on the product concentration calculation. The detection process is simple and convenient, providing a guarantee for the efficient operation of plasma in industrial applications.

[0088] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0089] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0090] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for detecting the type and concentration of plasma products, characterized in that: The following steps are involved: Based on the collected real-time temperature when the plasma is generated, a spatial temperature distribution diagram inside the plasma reaction chamber at different discharge voltages at different times is obtained; By simulating the discharge process in the plasma reaction chamber, the types and particle number density of the main plasma products on a short time scale are obtained; Based on the temperature distribution diagram and the discharge area when the plasma is generated, the generation rate of each product and the change of the substance concentration inside the plasma reaction chamber on a long time scale are obtained according to the particle number density.

2. A method for detecting the type and concentration of plasma products according to claim 1, characterized in that: In the process of obtaining the real-time temperature, a high voltage is selected as the excitation power supply to stimulate the generation of plasma. The gas breakdown near the ground electrode generates plasma. The real-time temperature of the ground electrode and the change in the center temperature of the ground electrode after the plasma is generated are obtained as the initial temperature of the calculation input.

3. A method for detecting the type and concentration of plasma products according to claim 2, characterized in that: In the process of obtaining the temperature distribution diagram, the center temperature of the ground electrode is used as the heat source. On the basis of considering the heat exchange with the outside air, the spatial temperature distribution diagram inside the plasma reaction chamber at different discharge voltages at different times is obtained. Among them, the heat exchange with the outside air includes two parts, one part is transmitted from the ground electrode to the dielectric sheet, and the other part is the heat exchange between the air inside the cavity and the outside through the cavity wall.

4. A method for detecting the type and concentration of plasma products according to claim 3, characterized in that: In the process of obtaining heat exchange with the outside air, the heat transfer mode between the ground electrode and the dielectric sheet above after heating is heat conduction, and its thermodynamic equation is as follows: The heat transfer between the ground electrode and the gas below is thermal convection, and its thermodynamic equation is expressed as: There is heat convection between the cavity and the outside air, and its thermodynamic equation is expressed as: -n·q=q0;q0=h(T Text -T0); Where q is the heat of thermal conduction; q0 is the heat of thermal convection; Q ted is the initial heat source, which is 0; k is the solid heat transfer coefficient; h is the air heat transfer coefficient; ν g is the flow rate of gas during natural convection; ρ is the density of gas; C ρ is the constant pressure specific heat capacity of air; T g is the gas temperature rise; T s is the electrode temperature rise; A s is the comprehensive heat transfer coefficient of the electrode; T0 is the room temperature; T ext is the temperature at the interface between the cavity and the air.

5. A method for detecting the type and concentration of plasma products according to claim 4, characterized in that: In the simulation of the discharge process in the plasma reaction chamber, it is assumed that there are only N2, O2 and water vapor in the air, the water vapor accounts for 0.03%, the volume ratio of N2 and O2 is 4:1, and the initial number density of each charged particle is 10 13 m- 3 ; Simplify the discharge simulation process in the plasma reaction chamber and obtain the particle number density of the main plasma products within a discharge cycle.

6. A method for detecting the type and concentration of plasma products according to claim 5, characterized in that: In the process of obtaining the discharge area, the actual discharge area is converted and calculated according to the RGB component information of the discharge image, and the discharge area when the plasma is generated is obtained.

7. A method for detecting the type and concentration of plasma products according to claim 6, characterized in that: In the process of obtaining the generation rate of each product and the change of substance concentration inside the plasma reaction chamber on a long time scale, the addition rate of each substance per unit volume in each cycle is obtained according to the discharge area and the particle number density of the main plasma products in one discharge cycle, and then the concentration of the product is obtained, wherein the change of substance concentration in the reaction chamber is obtained through zero-dimensional chemical reaction simulation.

8. A system for detecting the type and concentration of plasma products, characterized in that: The system is used to implement a method for detecting the type and concentration of plasma products as claimed in any one of claims 1 to 7, and the system comprises: The electrode temperature acquisition module is used to measure and collect the center temperature of the grounding electrode; The power drive module is used to provide high voltage as an excitation power source to stimulate the generation of plasma; Temperature simulation module, used to obtain the thermodynamic distribution of the internal area of ​​the plasma reaction chamber; Plasma simulation module, used to simulate the discharge process in the plasma reaction chamber and realize the particle number density of the main plasma products on a short time scale; An image recognition and calculation module is used to realize discharge image recognition and discharge area calculation, wherein the actual discharge area is calculated by collecting discharge image information and converting it according to the RGB component information of the discharge image; The chemical reaction simulation module is used to calculate the generation rate of various products inside the plasma reaction chamber on a long time scale.

Images