Microwave plasma torch generating apparatus and automatic ignition method thereof

Abstract

This invention relates to a microwave plasma torch generator and its automatic ignition method. The generator includes a microwave plasma torch assembly and a microwave generating assembly. The microwave plasma torch assembly includes a coaxial resonant cavity, a rectangular resonant cavity, a quartz tube, and a metal nozzle. The coaxial resonant cavity is connected to the quartz tube, which passes through the rectangular resonant cavity. One end of the metal nozzle is inserted into the cavity of both the coaxial and rectangular resonant cavities. The microwave generating assembly generates microwaves that are input to the microwave plasma torch assembly. The resonant frequency of the microwave plasma torch assembly is the same as the frequency of the microwaves. This invention solves the problem of not being able to place a metal tip or a device for focusing an electric field within the microwave plasma torch generator, achieving automatic ignition and ensuring the reliable and stable operation of the microwave plasma torch. It also reduces electrode contamination, whereas in the prior art, the presence of a metal tip or a device for focusing an electric field within the generator generally causes electrode contamination.

Description

Technical Field

[0001] This invention relates to the field of microwave plasma technology, and in particular to a microwave plasma torch generator and its automatic ignition method. Background Technology

[0002] The generation of plasma within the discharge tube of a microwave plasma torch requires an electric field strength in the generating device to reach the breakdown field strength of the working gas in order to ionize the working gas and generate active plasma components. At atmospheric pressure, the electric field strength required to excite plasma is often much higher than the electric field strength needed to sustain it. This is especially true in microwave plasma discharge, where a high-intensity local electric field is required to excite the working gas discharge. For continuous-wave microwave plasma discharge, a single ignition followed by removal of the excitation device is sufficient to maintain the plasma discharge process through continuous microwave input coupling. Therefore, to achieve the breakdown field strength required for gas breakdown within the microwave plasma torch generator, a metal tip or a device for focusing the electric field is typically installed within the generator. However, since these devices are not present in typical microwave plasma torch generators, a metal tip must be manually or automatically used to break down the working gas and generate plasma during microwave plasma ignition.

[0003] Currently, the commonly used excitation devices are either Tesla coils or tungsten electrodes applied with AC high voltage at the waveguide coupling port for ignition, or the discharge area is pumped down to a low pressure for direct ignition, and then the pressure is increased to atmospheric pressure to complete the process. This ignition method has a low degree of automation, and the components required for tip discharge are complex in structure, inconvenient to operate, not stable or reliable enough, and the components have short lifespans and are prone to wear and tear. Summary of the Invention

[0004] This invention addresses the technical problems existing in the prior art by providing a microwave plasma torch generator and its automatic ignition method. It solves the problem that it is impossible to place a metal tip or a device for focusing an electric field inside the microwave plasma torch generator, thereby achieving automatic ignition and ensuring the reliable and stable operation of the microwave plasma torch. It can also reduce electrode contamination, whereas in the prior art, the presence of a metal tip or a device for focusing an electric field inside the generator generally causes electrode contamination.

[0005] According to a first aspect of the present invention, a microwave plasma torch generating device is provided, comprising: a microwave plasma torch assembly and a microwave generating assembly; the microwave plasma torch assembly comprising: a coaxial resonant cavity, a rectangular resonant cavity, a quartz tube and a metal nozzle;

[0006] After the cavity of the coaxial resonant cavity is connected to the quartz tube, the quartz tube passes through the cavity of the rectangular resonant cavity; the metal nozzle is inserted into the cavity of the coaxial resonant cavity and the rectangular resonant cavity through one end of the coaxial resonant cavity;

[0007] The microwave generating component generates microwaves that are input into the microwave plasma torch component.

[0008] The resonant frequency of the microwave plasma torch assembly is the same as the frequency of the microwave.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Optionally, the microwave generating component includes: a magnetron and a water load;

[0011] The water load has a circulator; the magnetron and the rectangular resonant cavity are respectively connected to the two ends of the circulator of the water load; the magnetron generates microwaves input to the device.

[0012] Optionally, the generating device further includes: a microwave measurement component for measuring the frequency of the microwaves emitted by the magnetron, the microwave measurement component including: a waveguide with a coupler, a water-loaded diode, and a spectrum analyzer;

[0013] After the magnetron is connected to the first water load, the first water load is connected to the waveguide with coupler, and then the waveguide with coupler is connected to the second water load.

[0014] Water is supplied to water load one and water load two, and the spectrum analyzer is connected to the waveguide via a coaxial cable;

[0015] The spectrum analyzer measures the frequency of the microwaves emitted by the magnetron.

[0016] Optionally, the process of the microwave measurement component measuring the frequency of the microwaves emitted by the magnetron further includes:

[0017] The minimum, maximum, and increment values ​​of the microwave output power are set. The microwave output power is then increased sequentially from the minimum value to the maximum value according to the increment. Based on the frequency of the maximum amplitude of the spectrum displayed by the spectrum analyzer, the correspondence between the frequency of the microwave emitted by the magnetron and the microwave power is obtained.

[0018] Optionally, the generating device further includes a resonance frequency measuring component for measuring the resonance frequency of the microwave plasma torch assembly, the resonance frequency measuring component including: a network analyzer and a coaxial-to-rectangular waveguide;

[0019] The network analyzer is connected to the coaxial-to-rectangular waveguide via a coaxial cable, and the rectangular portion of the coaxial-to-rectangular waveguide is connected to the microwave plasma torch assembly.

[0020] The resonant frequency of the microwave plasma torch assembly is measured using the network analyzer.

[0021] Optionally, the microwave plasma torch assembly further includes three pins disposed on the rectangular resonant cavity.

[0022] According to a second aspect of the present invention, an automatic ignition method for a microwave plasma torch generator is provided, comprising:

[0023] Step 1: Measure the resonant frequency of the microwave plasma torch assembly and the frequency of the microwaves generated by the microwave generating assembly;

[0024] Step 2: Adjust the resonant frequency of the microwave plasma torch assembly to be the same as the frequency of the microwaves generated by the microwave generating assembly;

[0025] Step 3: Connect the microwave plasma torch assembly to the microwave generating assembly, and supply gas through the metal nozzle;

[0026] Step 4: Turn on the power of the microwave generating component and increase the output microwave power according to the set increment until the plasma is ignited in the quartz tube.

[0027] Optionally, step 2 includes:

[0028] Move and adjust the distance of the metal nozzle entering the coaxial resonant cavity and adjust the three pins set on the rectangular resonant cavity to adjust the resonant frequency of the microwave plasma torch assembly to the frequency of the microwave generated by the microwave generating assembly, and adjust the output power of the microwave generated by the microwave plasma torch assembly to 25%-60% of the maximum output power;

[0029] Lock the position of the metal nozzle with a locking nut.

[0030] This invention provides a microwave plasma torch generator and its automatic ignition method, which achieves automatic ignition and a continuous, stable plasma torch through a combination of a coaxial resonant cavity and a rectangular resonant cavity. The coaxial resonant cavity, located below the rectangular resonant cavity, is composed of a movable metal nozzle and a tangential gas supply unit. The tangential gas supply unit is mainly used for gas supply, which forms plasma after being excited by microwaves; the coaxial resonant cavity is mainly used for plasma ignition; and the rectangular resonant cavity is mainly used to maintain the continuous and stable operation of the plasma torch. This method not only enables automatic ignition but also features a simple structure and convenient operation; it reduces electrode contamination, whereas existing technologies typically incorporate metal tips or devices that concentrate electric fields within the generator, leading to electrode contamination. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an embodiment of a microwave plasma torch generator provided by the present invention;

[0032] Figure 2 A simulation diagram illustrating the change in electric field intensity in a rectangular resonant cavity and a coaxial resonant cavity before and after plasma ignition, provided for embodiments of the present invention.

[0033] Figure 3 This is a schematic diagram of the structure of the magnetron measured by the spectrum analyzer provided in an embodiment of the present invention;

[0034] Figure 4 A graph showing the relationship between the microwave output power and frequency of a magnetron provided in an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of a structure for adjusting the resonant frequency of a resonant cavity, provided in an embodiment of the present invention;

[0036] Figure 6 The simulation results of the resonant frequency of the resonant cavity at different nozzle positions are shown in the embodiment of the present invention.

[0037] The attached diagram lists the components represented by each number as follows:

[0038] 1. Magnetron, 2. Water load one, 3. Three pins, 4. Metal nozzle, 5. Coaxial resonant cavity, 6. Rectangular resonant cavity, 7. Quartz tube, 11. Waveguide with coupler, 12. Water load two, 13. Spectrum analyzer, 21. Network analyzer, 22. Coaxial to rectangular waveguide. Detailed Implementation

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0040] Figure 1 This is a schematic diagram of an embodiment of a microwave plasma torch generator provided by the present invention, as shown below. Figure 1 As shown, the device includes a microwave plasma torch assembly and a microwave generating assembly; the microwave plasma torch assembly includes a coaxial resonant cavity 5, a rectangular resonant cavity 6, a quartz tube 7, and a metal nozzle 4.

[0041] After the cavity of the coaxial resonant cavity 5 is connected to the quartz tube 7, the quartz tube 7 passes through the cavity of the rectangular resonant cavity; the metal nozzle 4 is inserted into the cavity of the coaxial resonant cavity 5 and the rectangular resonant cavity 6 through one end of the coaxial resonant cavity 5.

[0042] The microwave generating component generates microwaves that are input to the microwave plasma torch component.

[0043] The resonant frequency of the microwave plasma torch assembly is the same as the frequency of the microwave.

[0044] like Figure 2The diagram shown is a simulation illustration of the changes in electric field intensity in a rectangular resonant cavity and a coaxial resonant cavity before and after plasma ignition, provided in an embodiment of the present invention. Figure 2 As can be seen, a coaxial resonant cavity is a microwave resonant device based on a coaxial structure, composed of coaxial conductors, including an inner conductor (center conductor) and an outer conductor (outer shielding layer), sealed at both ends by short-circuit plates, suitable for wide-band, low-loss applications. A rectangular resonant cavity is composed of cylindrical conductors, sealed at both ends by metal covers, forming a closed cylindrical cavity, suitable for multi-band applications and high-power microwave systems. Coaxial resonant cavities have high mass and a sharp, narrow resonance curve, while cylindrical resonant cavities have low mass and a wide resonance curve. Due to the high mass characteristic of the coaxial resonant cavity, a high electric field is formed at the tip of the metal nozzle, achieving the high electric field required for plasma ignition. The low-mass, wide-resonance-curve rectangular resonant cavity effectively maintains the continuous operation of the plasma torch ignited by the high-field coaxial resonant cavity. Because plasma has a dielectric constant, when the plasma inside the resonant cavity is ignited, the dielectric constant changes throughout the cavity, and the resonant frequency shifts. At this point, microwaves can no longer penetrate into the coaxial resonant cavity and are confined within a transparent quartz discharge tube. Since the dielectric constant of quartz is greater than 1, the volume of a cylindrical resonator is actually increased, which leads to a decrease in the resonant frequency of the resonant cavity. This phenomenon must be taken into account when designing the size of a cylindrical resonant cavity.

[0045] The present invention provides a microwave plasma torch generator that solves the problem that it is impossible to place a metal tip or a device for focusing an electric field inside the microwave plasma torch generator, thereby achieving automatic ignition and making the microwave plasma torch reliable and stable; it can reduce electrode contamination, whereas in the prior art, the presence of a metal tip or a device for focusing an electric field inside the generator generally causes electrode contamination.

[0046] Example 1

[0047] Embodiment 1 provided by the present invention is an embodiment of a microwave plasma torch generator provided by the present invention, combined with... Figure 1 It is known that the embodiment of the generating device includes: a coaxial resonant cavity 5, a rectangular resonant cavity 6, a quartz tube 7, and a metal nozzle 4.

[0048] After the cavity of the coaxial resonant cavity 5 is connected to the quartz tube 7, the quartz tube 7 passes through the cavity of the rectangular resonant cavity; the metal nozzle 4 is inserted into the cavity of the coaxial resonant cavity 5 and the rectangular resonant cavity 6 through one end of the coaxial resonant cavity 5.

[0049] The microwave generating component generates microwaves that are input to the microwave plasma torch component.

[0050] The resonant frequency of the microwave plasma torch assembly is the same as the frequency of the microwave.

[0051] To achieve high-quality ignition of the plasma by the coaxial resonant cavity, its resonant frequency must be perfectly matched to the microwave frequency provided by the magnetron. Since not all magnetrons emit their microwave frequencies exactly at their nominal frequencies, and because the frequency depends on the output power, the magnetron must be measured using a spectrum analyzer. To ensure a perfect match between the coaxial resonant cavity's resonant frequency and the magnetron's microwave frequency, a network analyzer is also needed to measure the resonant frequency, achieved by moving the metal nozzle up and down to match the magnetron's microwave frequency. To achieve the high electric field at the nozzle tip required for plasma ignition, a three-pin is needed, installed between the microwave plasma torch (containing the metal nozzle, coaxial resonant cavity, rectangular resonant cavity, and quartz tube) and the magnetron. Adjusting the three-pin maximizes forward power and minimizes reflected power.

[0052] In one possible embodiment, the microwave generating component includes a magnetron 1 and a water load 2.

[0053] Water load 2 has a circulator; magnetron 1 and rectangular resonant cavity 6 are connected to the two ends of the circulator of water load 2 respectively; magnetron 1 generates microwaves for input device.

[0054] The circulator directs the input signal to the water load while isolating reflected waves and protecting the source. The water load absorbs microwave energy through water flow and is typically used in high-power applications such as radar testing or particle accelerators.

[0055] In one possible embodiment, such as Figure 3 The diagram shown is a schematic representation of the structure of a spectrum analyzer for measuring a magnetron according to an embodiment of the present invention. Figure 3 It is known that the generating device also includes a microwave measurement component for measuring the frequency of microwaves emitted by the magnetron, the microwave measurement component including a waveguide 11 with a coupler, a water load 12 and a spectrum analyzer 13.

[0056] After the magnetron 1 is connected to the water load 2, the water load 2 is connected to the waveguide 11 with coupler, and then the waveguide 11 with coupler is connected to the water load 12.

[0057] Water supply load 12 and water load 212 are supplied with water, and spectrum analyzer 13 is connected to waveguide via coaxial cable.

[0058] The spectrum analyzer 13 measures the frequency of the microwaves emitted by the magnetron.

[0059] A waveguide with a coupler is a passive microwave device that combines waveguide transmission and signal coupling functions. It is mainly used for directional transmission, signal distribution, or power monitoring of electromagnetic waves (especially in the microwave band).

[0060] In practice, a 20dB attenuator is inserted into the spectrum analyzer, and the magnetron is powered on. The spectrum of the emitted microwaves will then be displayed on the spectrum analyzer. The 20dB attenuator is used to protect the spectrum analyzer from excessive power exceeding 1W.

[0061] A spectrum analyzer is a versatile electronic measuring instrument used to study the spectral structure of electrical signals. It measures signal parameters such as signal distortion, modulation spectrum purity, frequency stability, and intermodulation distortion. A spectrum analyzer is an essential tool for measuring radio signals and is commonly used in the research, development, production, and testing of electronic products. Therefore, it is widely used and is often referred to as the engineer's RF multimeter.

[0062] In one possible embodiment, the process of the microwave measurement assembly measuring the frequency of the microwaves emitted by the magnetron further includes:

[0063] Set the minimum, maximum, and increment values ​​of the microwave output power. Increase the microwave output power from the minimum value to the maximum value sequentially according to the increment. Based on the frequency of the maximum amplitude of the spectrum displayed by the spectrum analyzer, obtain the correspondence between the frequency of the microwave emitted by the magnetron and the microwave power.

[0064] like Figure 4 The diagram shown illustrates the relationship between the microwave output power and frequency of a magnetron according to an embodiment of the present invention. In practice, magnetrons with output power less than 10% of their maximum output power typically exhibit a very wide spectrum with many different peaks, making them unusable. By increasing the microwave power from 10% to the maximum output power in increments of 5% to 10%, the frequency of the maximum amplitude of the spectrum displayed by the spectrum analyzer is determined each time, thus deriving the correspondence between the output microwave frequency and microwave power.

[0065] In one possible embodiment, such as Figure 5 The diagram shown is a schematic representation of a structure for adjusting the resonant frequency of a resonant cavity according to an embodiment of the present invention. Figure 5 It is understood that the generating device also includes a resonance frequency measuring component for measuring the resonance frequency of the microwave plasma torch assembly. The resonance frequency measuring component includes a network analyzer 21 and a coaxial-to-rectangular waveguide 22.

[0066] The network analyzer 21 is connected to the coaxial to rectangular waveguide 22 via a coaxial cable. The rectangular portion of the coaxial to rectangular waveguide 22 is connected to the microwave plasma torch assembly.

[0067] The resonant frequency of the microwave plasma torch assembly was measured using a network analyzer 21.

[0068] like Figure 6 The figure shown is a simulation result of the resonant frequency of the resonant cavity provided in the embodiment of the present invention at different nozzle positions.

[0069] A network analyzer is a comprehensive microwave measurement instrument capable of performing sweeping measurements over a wide bandwidth to determine network parameters. Its full name is Microwave Network Analyzer. A network analyzer is a novel instrument for measuring network parameters. It can directly measure the complex scattering parameters of active or passive, reversible or irreversible two-port and one-port networks, and provide the amplitude, phase, and frequency characteristics of each scattering parameter in a swept-frequency manner. An automatic network analyzer can perform point-by-point error correction on the measurement results and calculate dozens of other network parameters, such as input reflection coefficient, output reflection coefficient, voltage standing wave ratio, impedance (or admittance), attenuation (or gain), phase shift, group delay, and other transmission parameters, as well as isolation and directivity. This patent primarily uses a network analyzer to measure the phase and frequency characteristics of a passive microwave plasma torch assembly.

[0070] In one possible embodiment, the microwave plasma torch assembly further includes three pins 3 disposed on the rectangular resonant cavity.

[0071] Example 2

[0072] Embodiment 2 of the present invention is an embodiment of an automatic ignition method for a microwave plasma torch generator provided by the present invention. This embodiment of the automatic ignition method includes:

[0073] Step 1: Measure the resonant frequency of the microwave plasma torch assembly and the frequency of the microwaves generated by the microwave generating assembly.

[0074] Step 2: Adjust the resonant frequency of the microwave plasma torch assembly to be the same as the frequency of the microwaves generated by the microwave generating assembly.

[0075] In one possible embodiment, step 2 includes:

[0076] Move and adjust the distance of the metal nozzle into the coaxial resonant cavity and adjust the three pins set on the rectangular resonant cavity to adjust the resonant frequency of the microwave plasma torch assembly to the frequency of the microwave generated by the microwave generating assembly, and adjust the output power of the microwave generated by the microwave plasma torch assembly to 25%-60% of the maximum output power.

[0077] Lock the position of the metal nozzle with the locking nut.

[0078] Step 3: Connect the microwave plasma torch assembly to the microwave generating assembly and supply gas through the metal nozzle.

[0079] In practice, the gas supply is connected to the microwave plasma torch and the gas supply valve is opened.

[0080] Step 4: Turn on the power of the microwave generating component and increase the output microwave power according to the set amplification until the plasma is ignited in the quartz tube.

[0081] In practice, the output power is adjusted to a low power of 10%, and the microwave power is slowly increased over 10 to 60 seconds until the plasma is ignited in the quartz tube of the microwave plasma torch.

[0082] In subsequent use, steps 1-4 can be followed to achieve automatic ignition of atmospheric pressure microwave plasma.

[0083] It is understood that the automatic ignition method of the microwave plasma torch generator provided by the present invention corresponds to the microwave plasma torch generator provided in the foregoing embodiments. The relevant technical features of the automatic ignition method of the microwave plasma torch generator can be referred to the relevant technical features of the microwave plasma torch generator, and will not be repeated here.

[0084] This invention provides a microwave plasma torch generator and its automatic ignition method, which achieves automatic ignition and a continuous, stable plasma torch through a combination of a coaxial resonant cavity and a rectangular resonant cavity. The coaxial resonant cavity, located below the rectangular resonant cavity, is composed of a movable metal nozzle and a tangential gas supply unit. The tangential gas supply unit is mainly used for gas supply, which forms plasma after being excited by microwaves; the coaxial resonant cavity is mainly used for plasma ignition; and the rectangular resonant cavity is mainly used to maintain the continuous and stable operation of the plasma torch. This method not only enables automatic ignition but also features a simple structure and convenient operation; it reduces electrode contamination, whereas existing technologies typically include metal tips or devices that concentrate electric fields, which can cause electrode contamination.

[0085] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0086] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0087] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0088] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0089] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0090] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0091] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A microwave plasma torch generating device, characterized in that, The device includes: a microwave plasma torch assembly and a microwave generating assembly; the microwave plasma torch assembly includes: a coaxial resonant cavity, a rectangular resonant cavity, a quartz tube, and a metal nozzle; After the cavity of the coaxial resonant cavity is connected to the quartz tube, the quartz tube passes through the cavity of the rectangular resonant cavity; The metal nozzle is inserted into the cavity of the coaxial resonant cavity and the rectangular resonant cavity through one end of the coaxial resonant cavity; The microwave generating component generates microwaves that are input into the microwave plasma torch component. The resonant frequency of the microwave plasma torch assembly is the same as the frequency of the microwave. The microwave generating assembly includes: a magnetron and a water load; The water load is equipped with a circulator; the magnetron and the rectangular resonant cavity are respectively connected to the two ends of the circulator of the water load; the magnetron generates microwaves input to the device; The generating device further includes a microwave measurement component for measuring the frequency of the microwaves emitted by the magnetron, the microwave measurement component including a waveguide with a coupler, a water-loaded device, and a spectrum analyzer; After the magnetron is connected to the first water load, the first water load is connected to the waveguide with coupler, and then the waveguide with coupler is connected to the second water load. Water is supplied to water load one and water load two, and the spectrum analyzer is connected to the waveguide via a coaxial cable; The spectrum analyzer measures the frequency of the microwaves emitted by the magnetron; The process of measuring the frequency of the microwave emitted by the magnetron by the microwave measurement component further includes: setting a minimum value, a maximum value, and an increase in the output power of the microwave; increasing the output power of the microwave from the minimum value to the maximum value in sequence according to the increase; and obtaining the correspondence between the frequency of the microwave emitted by the magnetron and the microwave power based on the frequency of the maximum amplitude of the spectrum displayed by the spectrum analyzer.

2. The generating apparatus according to claim 1, characterized in that, The generating device further includes a resonance frequency measuring component for measuring the resonance frequency of the microwave plasma torch assembly, the resonance frequency measuring component including: a network analyzer and a coaxial-to-rectangular waveguide; The network analyzer is connected to the coaxial-to-rectangular waveguide via a coaxial cable, and the rectangular portion of the coaxial-to-rectangular waveguide is connected to the microwave plasma torch assembly. The resonant frequency of the microwave plasma torch assembly is measured using the network analyzer.

3. The generating apparatus according to claim 1, characterized in that, The microwave plasma torch assembly also includes three pins disposed on the rectangular resonant cavity.

4. An automatic ignition method for a microwave plasma torch generator as described in any one of claims 1-3, characterized in that, The ignition method includes: Step 1, measuring the resonant frequency of the microwave plasma torch assembly and the frequency of the microwaves generated by the microwave generating assembly; Step 2: Adjust the resonant frequency of the microwave plasma torch assembly to be the same as the frequency of the microwaves generated by the microwave generating assembly; Step 3: Connect the microwave plasma torch assembly to the microwave generating assembly, and supply gas through the metal nozzle; Step 4: Turn on the power of the microwave generating component and increase the output microwave power according to the set increment until the plasma is ignited in the quartz tube.

5. The automatic ignition method according to claim 4, characterized in that, Step 2 includes: moving and adjusting the distance of the metal nozzle entering the coaxial resonant cavity and adjusting the three pins set on the rectangular resonant cavity, adjusting the resonant frequency of the microwave plasma torch assembly to the frequency of the microwave generated by the microwave generating assembly, and adjusting the output power of the microwave generated by the microwave plasma torch assembly to 25%-60% of the maximum output power; Lock the position of the metal nozzle with a locking nut.

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