Microwave cold plasma generating device based on coaxial arrowhead structure

Abstract

The invention discloses a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure, and relates to the field of plasma generating devices, the microwave cold plasma generating device comprises an outer conductor sleeve, the inner part of the outer conductor sleeve comprises a cylindrical cavity and a conical cavity which are communicated, and the inner part of the outer conductor sleeve can be communicated with an air source; the inner conductor is arranged in the outer conductor sleeve, the inner conductor and the outer conductor sleeve are coaxially arranged, and the inner conductor is used for transmitting microwave energy to the conical cavity area; the inner conductor comprises a columnar part and an arrow part, one end of the columnar part is connected with the microwave source, the other end of the columnar part is connected with the opposite side of the tip of the arrow part, and the columnar part is used for transmitting microwave energy of the microwave source to the arrow part. According to the coaxial terminal, the tip end of the arrow part is arranged to be lower than the tip end of the conical cavity, the conical cavity is formed at the coaxial terminal, meanwhile, a unique arrowhead type inner conductor structure is adopted, internal gas circulation is not blocked, meanwhile, the electric field intensity of the coaxial terminal is improved, and low-power self-excitation working gas is facilitated to generate plasma.

Description

Technical Field

[0001] The invention relates to the field of plasma generating devices, and in particular to a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure. Background Art

[0002] Plasma is composed of electrons, ions, free radicals, photons and other neutral particles. Among them, electrons, ions and free radicals are active particles, which are very easy to react with the surface of other solid materials. Plasma treatment is carried out by taking advantage of this characteristic. Plasma is regarded as the fourth form of matter in addition to solid, liquid and gas. The excitation of the plasma state requires certain conditions, such as a certain low pressure (vacuum), a certain electric field or temperature, etc. Plasma can be divided into high-temperature plasma and low-temperature plasma according to temperature. The temperature of high-temperature plasma can range from one or two hundred degrees to tens of thousands of degrees. The temperature of the plasma jet itself is high, and the surface temperature will be higher after contact and collision with the solid phase. This type of plasma is only suitable for processing heat-resistant materials such as ceramics and metals. The temperature of low-temperature plasma can be controlled close to room temperature, which is suitable for processing heat-resistant materials such as plastics, silicone, and chips.

[0003] Microwave is one of the methods of plasma generation. Compared with other traditional plasmas, microwave plasma has the advantages of low base temperature, stable and easy-to-control microwave generator, efficient microwave discharge, high safety factor, and quiet plasma. Its plasma generation chamber and processing chamber can be separated and combined, and the process is flexible. Atmospheric pressure microwave plasma jet has the advantages of moderate gas temperature, stable system, and low cost. It is widely used in many different fields such as material surface cleaning and etching, sewage treatment, polymer material surface modification, wound disinfection, and cancer cell treatment. Among them, the active free radicals and high-energy particles of the plasma jet will significantly affect the effect of the application. At present, there have been many advances in the research of microwave plasma technology in China, but it is still a long way from commercialization.

[0004] There have been some studies on atmospheric microwave plasma jets. For example, in the prior art, atmospheric microwave plasma equipment mainly includes two structures. The first is a rectangular waveguide structure, and most of its structures use a rectangular waveguide as the plasma excitation area. A microwave feed port is provided at the left end of the rectangular waveguide for feeding microwaves, and a metal shielding plate is provided at the right end so that the incident and reflected waves form standing waves in the rectangular waveguide. The ceramic tube runs through the rectangular waveguide from top to bottom, and microwaves are used to excite the reaction gas in the ceramic tube to generate microwave plasma; the second is a plasma torch structure, which usually uses a resonant cavity composed of a cylindrical cylindrical cavity, which has the advantage of focusing the electric field, so that microwave energy is gathered in the area to be excited to generate a large electric field by compressing the waveguide, and a high-voltage probe is used for tip discharge. The plasma and the cylindrical resonant cavity form a coaxial structure, and the gas is continuously introduced. On the one hand, the gas composition of the plasma is maintained, and on the other hand, the plasma is driven to flow out in a directional manner. At the same time, the gas takes away a large amount of heat, which plays a role in heat dissipation.

[0005] However, in the above two structures, there are still the following problems in self-ignition, plasma maintenance and safety: higher microwave power is required to stimulate the formation of plasma; the plasma energy conversion efficiency is not high; the atmospheric pressure plasma torch is unstable, and the plasma is difficult to maintain even under harsh conditions; the synthetic materials have more impurities, especially when a metal wire is required for "ignition", which easily introduces pollutants; at the same time, because the plasma contains a large number of free electrons, the plasma is extremely conductive. After the plasma generator generates plasma, the high-density columnar plasma acts as an electromagnetic energy conduction medium, which is equivalent to an "antenna" and will radiate electromagnetic waves outward. The existing technology does not control microwave radiation, and it is unsafe for long-term use. Summary of the invention

[0006] The object of the present invention is to provide a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure, which is combined with an outer conductor sleeve with a conical cavity and an inner conductor with an arrowhead portion to solve the problem of difficulty in self-ignition and difficulty in preparing low-temperature plasma in the prior art.

[0007] The embodiment of the present invention is achieved through the following technical solutions:

[0008] The embodiment of the present invention provides a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure, comprising:

[0009] The outer conductor sleeve is provided as a peripheral structure of the plasma generating area, and the inner part of the outer conductor sleeve includes a cylindrical cavity and a conical cavity which are connected to each other, and the inner part of the outer conductor sleeve can be connected to a gas source;

[0010] The inner conductor is arranged in the outer conductor sleeve and is coaxially arranged with the outer conductor sleeve, an annular gap is formed between the inner conductor and the outer conductor sleeve, and the inner conductor is used to transmit microwave energy to the conical cavity area;

[0011] The inner conductor includes a columnar portion and an arrow portion, one end of the columnar portion is connected to the microwave source, and the other end is connected to the side opposite to the tip of the arrow portion, and the columnar portion is used to transmit the microwave energy of the microwave source to the arrow portion;

[0012] The columnar portion is located in the cylindrical cavity, and the arrowhead portion is located in the conical cavity;

[0013] The tip of the arrow portion is arranged at the tip side of the conical cavity, an emission hole is arranged on the outer conductor sleeve at the tip side of the conical cavity, the tip end face of the arrow portion is lower than the end face of the emission hole, and the emission hole is arranged to emit cold plasma into the external environment of the outer conductor sleeve;

[0014] The conical cavity is configured to converge the electric field in the microwave energy at the tip of the arrow portion, thereby increasing the electric field intensity at the tip of the arrow portion and achieving self-ignition to excite the gas source to generate plasma.

[0015] Further, the outer conductor sleeve includes a cylindrical sleeve and a conical sleeve, the cylindrical cavity is located in the cylindrical sleeve, the conical cavity is located in the conical sleeve, and the top of the cylindrical sleeve is detachably connected to the bottom of the conical sleeve;

[0016] The diameter of the cylindrical cavity is equal to the maximum diameter of the conical cavity.

[0017] Furthermore, a limiting mechanism is arranged inside the outer conductor sleeve, and the limiting mechanism is arranged to limit the inner conductor and the outer conductor sleeve coaxially.

[0018] Furthermore, an annular groove is arranged in the cylindrical sleeve, and the limiting mechanism is a limiting gasket, which is arranged in the annular groove, and the limiting gasket is coaxially arranged with the outer conductor sleeve;

[0019] A through hole is provided in the center of the limiting gasket, the columnar portion passes through the through hole, and the arrow portion is located above the limiting gasket; a plurality of vents are provided on the limiting gasket, and the vents are used to flow the air source in the cavity below the limiting gasket to the cavity above the limiting gasket.

[0020] Further, the columnar portion includes a lower external connecting portion and an upper internal connecting portion which are axially connected, the lower external connecting portion is connected to a microwave source connecting mechanism, and the diameter of the through hole is larger than the diameter of the upper internal connecting portion and smaller than the outer diameter of the lower external connecting portion;

[0021] The arrow portion includes an axially connected tip portion and a connecting portion, the connecting portion is a hollow structure opening downward, and the upper internally connected portion of the columnar portion can be inserted into the hollow structure;

[0022] The upper internal connection part is configured to penetrate through the through hole and then be inserted into the hollow structure, so as to fix the limit washer at the connection between the columnar part and the arrow part;

[0023] The outer diameter of the connecting portion is greater than the diameter of the through hole.

[0024] Further, when the limiting gasket is fixed at the connection between the columnar portion and the arrow portion, the upper end surface of the lower external connection portion fits with the bottom of the limiting gasket, and the lower end surface of the connection portion fits with the upper end of the limiting gasket;

[0025] The upper inner connecting part is threadedly connected to the connecting part.

[0026] Furthermore, the microwave source connection mechanism comprises a first connection end and a second connection end, a mounting plate is arranged between the first connection end and the second connection end, and the mounting plate is fixedly connected to the bottom of the cylindrical sleeve by a plurality of bolt mechanisms;

[0027] The first connection end passes through the bottom of the cylindrical sleeve and is connected to the lower external connection part of the columnar part. The mounting plate and the second connection end are arranged on the outside of the cylindrical sleeve. The second connection end is used to connect the microwave source.

[0028] Furthermore, an air intake assembly is provided at the bottom of the cylindrical sleeve, the air intake assembly is connected to the cylindrical cavity, and the air intake assembly is arranged to be connected to the air source pipeline at its outer side and transport the air source in the air source pipeline into the cylindrical cavity;

[0029] The flow direction of the gas source delivered by the air inlet component entering the cylindrical cavity for the first time is horizontal.

[0030] Furthermore, a blocking mechanism is provided above the outer conductor sleeve, and the blocking mechanism is configured to block microwaves from passing through the emission hole and allow gas to flow, thereby preventing microwave energy from leaking after exciting plasma.

[0031] Furthermore, the blocking mechanism includes four blocking blocks, there is a gap between two adjacent blocking blocks, the four blocking blocks enclose a conical structure, the diameter of the conical structure gradually decreases from bottom to top, the conical structure is provided with a central channel, the central channel is configured to connect the launch hole and the external environment, and the central channel is coaxially arranged with the launch hole.

[0032] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects:

[0033] 1. In the generating device provided by the embodiment of the present invention, the outer conductor sleeve is the peripheral structure of the plasma generating area, and a cylindrical cavity and a conical cavity are arranged inside for connecting the gas source. The inner conductor and the outer conductor sleeve are coaxially arranged, and the annular gap formed therebetween is the key area for converting microwave energy into an electric field. The inner conductor is responsible for transmitting microwave energy from the microwave source to the conical cavity area.

[0034] When microwaves propagate in cylindrical cavities and conical cavities, due to the size and shape of the cavities, microwaves will form standing waves in the cavities, and the antinode of the standing wave is at the tip of the conical cavity, which is conducive to the generation of plasma. The columnar portion is located in the cylindrical cavity and transmits the energy of the microwave source to the arrow portion. The columnar portion helps to maintain the effective transmission of microwave energy and ensures that the energy does not attenuate too much before reaching the arrow portion. The arrow portion is located in the conical cavity, and its tip is the key area for plasma generation. The arrow portion concentrates the electric field at the tip, thereby generating a high electric field strength in this area, which is convenient for breaking through the gas and forming plasma.

[0035] Since the setting position of the arrow portion corresponds to the conical cavity, that is, the tip side of the conical cavity corresponds to the tip side of the arrow portion, the effective transfer and concentration of the electric field energy is guaranteed, so that the generation of plasma can be achieved at a lower microwave power, and self-ignition is achieved to excite the gas source to generate plasma, thereby improving energy efficiency.

[0036] At the same time, the structure of the conical cavity helps to control the morphology and jet length of the plasma, making it more uniform and stable. In addition, since the tip of the arrow is lower than the end face of the emission hole, it helps to prevent the plasma from directly contacting certain parts of the device, thereby protecting the device and ensuring stable generation of plasma.

[0037] 2. The outer conductor sleeve provided in the embodiment of the present invention includes a cylindrical sleeve and a conical sleeve. A cylindrical cavity is formed inside the cylindrical sleeve to accommodate the columnar portion of the inner conductor and provide a channel for the transmission of microwave energy; a conical cavity is formed inside the conical sleeve to help focus the electric field, especially near the tip of the arrow, which helps to excite plasma.

[0038] 3. The limiting mechanism provided in the embodiment of the present invention ensures the stability of the coaxial position of the inner conductor and the outer conductor sleeve. The limiting mechanism can be a limiting gasket, which cooperates with the annular groove of the cylindrical sleeve to achieve a detachable stable connection. A plurality of vents are provided on the limiting gasket, which not only ensures the correct position and coaxiality of the inner conductor, but also ensures that the circulation of gas in the annular gap is not affected.

[0039] 4. The embodiment of the present invention sets a barrier at the emitting hole, which is equivalent to a cut-off waveguide. It uses the cut-off frequency principle of electromagnetic waves in the waveguide. Below the cut-off frequency, electromagnetic waves cannot propagate in the waveguide, so microwaves can be cut off. In the plasma generating device, even after the plasma is excited, the device can effectively prevent the leakage of microwave energy, thereby improving the safety of operation.

[0040] 5. The gas source in the embodiment of the present invention enters the plasma generating device from a single gas inlet assembly, and is close to the input end of the microwave source connection mechanism. In actual use, the gas pipeline and the microwave source cable can be bundled together to form a traction line, and the pipeline or cable will not be bent when arranged on the same side. This structure not only makes the device neater, but also facilitates the operator to move and position, thereby improving the convenience of operation.

[0041] In general, an embodiment of the present invention provides a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure, which combines an outer conductor sleeve with a conical cavity and an inner conductor with an arrowhead portion, and sets the tip of the arrowhead portion to be lower than the tip of the conical cavity. A conical cavity is formed at the coaxial terminal, and a unique arrowhead-shaped inner conductor structure is adopted. While not blocking the internal gas flow, the electric field strength of the coaxial terminal is improved, which is convenient for low-power self-excited working gas to generate plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 A schematic diagram of the explosion structure of a microwave cold plasma generating device provided in an embodiment of the present invention;

[0044] Figure 2 A schematic cross-sectional structure diagram of a microwave cold plasma generating device provided in an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of the overall structure of a microwave cold plasma generating device provided in an embodiment of the present invention;

[0046] Figure 4 A wireframe diagram of the internal structure of a microwave cold plasma generating device provided in an embodiment of the present invention;

[0047] Figure 5 A structural diagram showing the relationship between the inner conductor, the limiting gasket and the microwave source connection mechanism provided in an embodiment of the present invention;

[0048] Figure 6 A structural diagram showing the relationship between the cylindrical sleeve, the inner conductor and the microwave source connection mechanism provided in an embodiment of the present invention;

[0049] Figure 7 A schematic diagram of the distribution of the electric field of a microwave plasma torch provided in an embodiment of the present invention outside a cylindrical cavity and a conical cavity;

[0050] Figure 8 A schematic diagram of the distribution of the electric field of a microwave plasma torch in a cylindrical cavity and a conical cavity provided in an embodiment of the present invention;

[0051] Fig. 9 A front view of a local enlarged distribution of the electric field of a microwave plasma torch at the tip provided by an embodiment of the present invention;

[0052] Fig.10 A top view of a local enlarged distribution of the electric field of a microwave plasma torch at the tip provided by an embodiment of the present invention.

[0053] Description of reference numerals:

[0054] 100, outer conductor sleeve; 101, cylindrical cavity; 102, conical cavity; 103, emitting hole; 104, cylindrical sleeve; 105, conical sleeve; 106, annular groove; 200, inner conductor; 201, columnar portion; 202, arrow portion; 203, lower external connecting portion; 204, upper internal connecting portion; 205, tip portion; 206, connecting portion; 300, limiting mechanism; 301, limiting gasket; 302, through hole; 303, vent; 400, microwave source connecting mechanism; 401, first connecting end; 402, second connecting end; 403, mounting plate; 404, bolt mechanism; 500, air inlet assembly; 501, connecting pipe; 502, mounting hole; 600, blocking mechanism; 601, blocking block; 602, central channel. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] Embodiment 1:

[0057] like Figure 1-4 As shown, Figure 1 This is a schematic diagram of the explosion structure of the microwave cold plasma generator. Figure 2 It is a schematic diagram of the cross-sectional structure of a microwave cold plasma generating device. Figure 3 This is a schematic diagram of the overall structure of the microwave cold plasma generator. Figure 4 The figure is a wireframe diagram of the internal structure of a microwave cold plasma generator. A microwave cold plasma generator with a coaxial arrowhead-shaped structure comprises:

[0058] The outer conductor sleeve 100 is provided as a peripheral structure of the plasma generating area, and includes a cylindrical cavity 101 and a conical cavity 102 which are connected to each other. The inner part of the outer conductor sleeve 100 can be connected to a gas source;

[0059] The inner conductor 200 is preferably made of brass and is disposed in the outer conductor sleeve 100 and is coaxially disposed with the outer conductor sleeve 100. An annular gap is formed between the inner conductor 200 and the outer conductor sleeve 100. The inner conductor 200 is used to transmit microwave energy to the conical cavity 102 area.

[0060] The inner conductor 200 includes a columnar portion 201 and an arrow portion 202. One end of the columnar portion 201 is connected to the microwave source, and the other end is connected to the side opposite to the tip of the arrow portion 202. The columnar portion 201 is used to transmit the microwave energy of the microwave source to the arrow portion 202.

[0061] The columnar portion 201 is located in the cylindrical cavity 101 , and the arrow portion 202 is located in the conical cavity 102 ;

[0062] The tip of the arrow portion 202 is arranged at the tip side of the conical cavity 102, and an emission hole 103 is arranged on the outer conductor sleeve 100 at the tip side of the conical cavity 102. The tip end surface of the arrow portion 202 is lower than the end surface of the emission hole 103, and the emission hole 103 is arranged to emit cold plasma into the external environment of the outer conductor sleeve 100;

[0063] The conical cavity 102 is configured to converge the electric field in the microwave energy at the tip of the arrow portion 202, so that the electric field intensity at the tip of the arrow portion 202 is increased, thereby achieving self-ignition to excite the gas source to generate plasma.

[0064] Specifically, the device provided in the embodiment of the present invention adopts a coaxial structure, that is, the inner conductor 200 is located on the central axis of the outer conductor sleeve 100, which can ensure the efficiency of concentrating and transmitting microwave energy. One end of the columnar portion 201 of the inner conductor 200 is connected to the microwave source, and the other end is connected to the arrow portion 202, which is responsible for transmitting the energy of the microwave source to the arrow portion 202. The setting of the conical cavity 102 does not block the internal gas flow, so that the electric field in the microwave energy is focused at the tip of the arrow portion 202, and a high electric field strength is generated at this point, which is sufficient to ionize the gas source molecules and generate plasma, that is, to achieve self-ignition.

[0065] The columnar portion 201 of the inner conductor 200 is directly connected to the microwave source to ensure effective energy transmission. The connection between the columnar portion 201 and the arrow portion 202 ensures that energy is transferred from the columnar portion 201 to the arrow portion 202. The arrangement of the arrow portion 202 helps focus the electric field. The outer conductor sleeve 100 is internally connected and can be connected to a gas source to provide the necessary gas for generating plasma. The tip of the arrow portion 202 is located below the emission hole 103 to ensure that the plasma can be guided to the external environment through the emission hole 103.

[0066] Since the electric field intensity at the tip of the arrow portion 202 is high, plasma can be generated under lower microwave energy input. The tip of the arrow portion 202 is located below the launch hole 103, which helps to reduce energy consumption and loss and improve the energy efficiency of the entire system. At the same time, it can prevent plasma from directly impacting the end face of the launch hole 103, reduce erosion and damage to the device material, and thus extend the service life of the equipment.

[0067] During operation, the generation and output of plasma can be controlled by adjusting the power of the microwave source and the flow rate of the gas source. The coaxial structure makes the device smaller and easier to integrate into various equipment.

[0068] The embodiment of the present invention makes full use of the principle of microwave energy and electric field focusing, and uses the special shape of the conical cavity 102 to enhance the electric field strength, without blocking the internal gas flow, so that the microwave energy is concentrated in the conical cavity 102. In particular, at the tip of the arrow portion 202, due to the tip effect, the electric field lines are more concentrated and the electric field strength is significantly increased. The electric field distribution is conducive to the gas molecules being more easily ionized at the tip of the arrow portion 202, and due to the concentration of the electric field, plasma can be generated at a lower microwave power. Among them, the cylindrical cavity 101 provides a stable environment, so that the inner conductor 200 can transmit the energy of the microwave source to the conical cavity 102 area, so that the microwave energy is evenly distributed in the cylindrical cavity 101, and then through the focusing effect of the conical cavity 102, the energy is concentrated at the tip of the arrow portion 202. Therefore, plasma is generated by self-ignition excitation, and the generated cold plasma can be used in various application fields such as surface treatment, disinfection, and material processing.

[0069] Furthermore, the outer conductor sleeve 100 includes a cylindrical sleeve 104 and a conical sleeve 105, the cylindrical sleeve 104 and the conical sleeve 105 are preferably made of brass, the cylindrical cavity 101 is located in the cylindrical sleeve 104, the conical cavity 102 is located in the conical sleeve 105, the top of the cylindrical sleeve 104 and the bottom of the conical sleeve 105 are detachably connected; the diameter of the cylindrical cavity 101 is equal to the maximum diameter of the conical cavity 102.

[0070] It should be noted that the cylindrical sleeve 104 and the conical sleeve 105 here can be arranged in an integral manner or in a spliced ​​manner, and there is no limitation here.

[0071] As a preferred embodiment of the present invention, the cylindrical sleeve 104 and the conical sleeve 105 are connected by a threaded structure, which not only ensures sufficient connection stability and sealing, but also provides a flexible and detachable connection structure, which facilitates the cleaning of the entire cavity and the maintenance and replacement of individual components, thereby improving the flexibility of use of the entire device.

[0072] Of course, in other embodiments, the connection method of the cylindrical sleeve 104 and the conical sleeve 105 is not limited to threaded connection, and can be connected by bonding, clamping, welding, etc., as long as sufficient connection stability and sealing effect can be achieved.

[0073] Back to the embodiment of the present invention, the cylindrical sleeve 104 provides a cylindrical cavity 101, and the conical sleeve 105 provides a conical cavity 102. The outer shapes of the cylindrical sleeve 104 and the conical sleeve 105 are not limited here, and can be set according to actual needs, as long as the purpose of providing the cylindrical cavity 101 and the conical cavity 102 can be achieved.

[0074] As a preferred embodiment of the present invention, the outer shapes of the cylindrical sleeve 104 and the conical sleeve 105 are both set to be cylindrical. The setting that the diameter of the cylindrical cavity 101 is equal to the maximum diameter of the conical cavity 102 in the embodiment of the present invention is conducive to smooth transition of energy, reducing energy loss during propagation, and also helps to maintain the stability of plasma.

[0075] In order to improve the relative position stability between the outer conductor sleeve 100 and the inner conductor 200, a limiting mechanism 300 can be provided in the outer conductor sleeve 100, and the limiting mechanism 300 is configured to limit the inner conductor 200 and the outer conductor sleeve 100 coaxially. The application of the coaxial limiting technology can ensure that the inner conductor 200 is correctly aligned in the cylindrical cavity 101, prevent deviation, and realize the effective transmission of microwave energy in the annular gap and the uniformity of plasma.

[0076] Specifically, the limiting mechanism 300 can be implemented in a mechanical manner, such as using a stop bolt, a retaining ring or a specially designed component to limit the movement of the inner conductor 200 to ensure that it remains in the correct position during assembly and operation.

[0077] It is important that the limiting mechanism 300 should be considered not to affect the transmission and flow of the gas during the setting process. Exemplarily, an annular groove 106 is provided in the cylindrical sleeve 104, and the limiting mechanism 300 is a limiting gasket 301, which is provided in the annular groove 106, and the limiting gasket 301 is coaxially provided with the outer conductor sleeve 100; a through hole 302 is provided at the center of the limiting gasket 301, the columnar portion 201 passes through the through hole 302, and the arrow portion 202 is located above the limiting gasket 301; a plurality of vents 303 are provided on the limiting gasket 301, and the vents 303 are used to circulate the gas source in the cavity below the limiting gasket 301 to the cavity above the limiting gasket 301.

[0078] Specifically, the annular groove 106 is located inside the cylindrical sleeve 104 and is used to install the limiting gasket 301, which limits the position and installation angle of the limiting gasket 301 in the outer conductor sleeve 100. The limiting gasket 301 is preferably installed horizontally, and there is a through hole 302 in the center of the limiting gasket 301, which is used for the columnar portion 201 of the inner conductor 200 to pass through, and the through hole 302 has a limiting effect on the inner conductor 200.

[0079] Preferably, the inner conductor 200 and the limiting gasket 301 are arranged vertically.

[0080] Among them, a plurality of vent holes 303 are provided on the limiting gasket 301 , and the limiting gasket 301 coaxially limits the inner conductor 200 through the center hole to ensure the correct position of the inner conductor 200 in the cylindrical sleeve 104 , and ensures gas circulation through the vent holes 303 on the limiting gasket 301 .

[0081] It should be noted that the material of the limiting gasket 301 is not limited here. The selection of the material of the limiting gasket 301 should take into account temperature resistance, chemical resistance, mechanical strength, creep resistance, processing performance, compatibility with the contact medium, cost-effectiveness and other aspects. Polytetrafluoroethylene is preferably used. Polytetrafluoroethylene has strong chemical stability and is an insulating material. It will not affect the electric field in the outer conductor sleeve 100, nor will it react chemically with plasma or gas.

[0082] It should also be noted that the size, number and arrangement of the through holes 302 on the limiting gasket 301 are not limited here, as long as the sufficient supporting performance of the limiting gasket 301 and the smooth flow of gas in the cavity can be guaranteed.

[0083] As a preferred embodiment of the present invention, the through holes 302 on the limiting gasket 301 are evenly distributed, and can be arranged in a circular array, for example. The even distribution of the through holes 302 helps the gas source to form a uniform airflow between the cavity below and above the limiting gasket 301, which helps to uniformly generate and maintain plasma.

[0084] For example, six through holes 302 are evenly distributed on the limiting gasket 301 and arranged in a circular array. Of course, in other embodiments, the number of through holes 302 can also be two, three, four, etc., and the arrangement is not limited to a circular array.

[0085] Embodiment 2:

[0086] The difference from Embodiment 1 is that the specific structure of the inner conductor 200 is set in detail.

[0087] For example, Figure 5 As shown, the columnar portion 201 includes an axially connected lower external portion 203 and an upper internal portion 204, the lower external portion 203 is connected to a microwave source connection mechanism 400, the diameter of the through hole 302 is larger than the diameter of the upper internal portion 204 and smaller than the outer diameter of the lower external portion 203; the arrow portion 202 includes an axially connected tip portion 205 and a connecting portion 206, the connecting portion 206 is a hollow structure opening downward, and the upper internal portion 204 of the columnar portion 201 can be inserted into the hollow structure; the upper internal portion 204 is configured to penetrate the through hole 302 and then be inserted into the hollow structure, fixing the limiting gasket 301 at the connection between the columnar portion 201 and the arrow portion 202; the outer diameter of the connecting portion 206 is larger than the diameter of the through hole 302.

[0088] Specifically, the lower external connection part 203 is the lower end part of the columnar part 201, connected to the microwave source connection mechanism 400, and used to receive energy from the microwave source. The upper internal connection part 204 is the upper end part of the columnar part 201, which is configured to be inserted into the hollow structure of the arrow part 202, and plays a role in connecting the columnar part 201 and the arrow part 202. The through hole 302 is set at the center of the limiting gasket 301, and is used for the upper internal connection part 204 of the columnar part 201 to pass through, so as to achieve the initial limiting of the limiting gasket 301 and the columnar part 201.

[0089] The diameter of the through hole 302 is set to be larger than the diameter of the upper inner portion 204 to ensure that the upper inner portion 204 can pass through smoothly, and smaller than the outer diameter of the lower outer portion 203 to ensure good sealing and fixation between the lower outer portion 203 and the limiting gasket 301.

[0090] Among them, the tip portion 205 is the front section of the arrow portion 202, located in the conical cavity 102, and is responsible for generating a high electric field strength at the tip to excite the gas source to generate plasma. The connecting portion 206 is the rear section of the arrow portion 202, which is a hollow structure and is designed to open downward so that the upper internal connection portion 204 of the columnar portion 201 can be inserted therein to achieve connection. The outer diameter of the connecting portion 206 is set to be larger than the diameter of the through hole 302. When the upper internal connection portion 204 passes through the through hole 302 and is inserted into the hollow structure of the connecting portion 206, the limiting gasket 301 can be fixed at the connection between the columnar portion 201 and the arrow portion 202 to ensure the stability and coaxiality of the entire inner conductor 200.

[0091] The above-mentioned connection structure ensures a tight connection between the columnar portion 201 and the arrow portion 202 of the inner conductor 200. At the same time, the through hole 302 on the limiting gasket 301 and the hollow structure of the connecting portion 206 are used to fix the limiting gasket 301, thereby ensuring the stability and coaxiality of the entire inner conductor 200, which helps to improve the efficiency of microwave energy transmission and the uniformity of plasma generation, and is also convenient for assembly and maintenance.

[0092] As a preferred embodiment of the present invention, when the limiting gasket 301 is fixed at the connection between the columnar portion 201 and the arrow portion 202, the upper end surface of the lower external connection portion 203 fits with the bottom of the limiting gasket 301, and the lower end surface of the connection portion 206 fits with the upper end of the limiting gasket 301; the upper internal connection portion 204 is threadedly connected to the connection portion 206. In this preferred structure, the limiting gasket 301 not only plays a role in fixing the inner conductor 200, but also ensures the precise alignment and coaxiality between the columnar portion 201 and the arrow portion 202.

[0093] Specifically, the structure helps to ensure the sealing and structural stability between the columnar portion 201 and the limiting gasket 301. At the same time, the lower end surface of the connecting portion 206 of the arrow portion 202 is also tightly fitted with the upper end of the limiting gasket 301, which further ensures the alignment and fixation between the arrow portion 202 and the limiting gasket 301. The upper internal connection portion 204 of the columnar portion 201 and the connecting portion 206 of the arrow portion 202 are connected by threads. The threaded connection allows fine adjustment during the assembly process to ensure the precise coaxiality and correct position of the inner conductor 200. The threaded connection structure also provides good mechanical strength to ensure that the connection between the columnar portion 201 and the arrow portion 202 will not loosen due to vibration or thermal expansion during the operation of the plasma generator.

[0094] Embodiment 3:

[0095] The difference from Embodiment 2 is that the microwave source connecting mechanism 400 is specifically configured.

[0096] For example, Figure 5 and Figure 6 As shown, the microwave source connection mechanism 400 includes a first connection end 401 and a second connection end 402, a mounting plate 403 is arranged between the first connection end 401 and the second connection end 402, and the mounting plate 403 is fixedly connected to the bottom of the cylindrical sleeve 104 by a plurality of bolt mechanisms 404; the first connection end 401 passes through the bottom of the cylindrical sleeve 104 and is connected to the lower external connection portion 203 of the columnar portion 201, the mounting plate 403 and the second connection end 402 are arranged on the outside of the cylindrical sleeve 104, and the second connection end 402 is used to connect the microwave source.

[0097] Specifically, the first connection end 401 is a part of the microwave source connection mechanism 400, connected to the lower external connection part 203 of the columnar part 201 of the inner conductor 200, and the connection method is preferably a threaded connection, which ensures good electromagnetic compatibility and sealing to prevent the loss of microwave energy. The second connection end 402 is another part of the connection mechanism, located outside the cylindrical sleeve 104, and is used to connect to an external microwave source. The mounting plate 403 is an intermediate structure connecting the first connection end 401 and the second connection end 402, and provides a stable platform for installing and fixing the entire microwave source connection mechanism 400.

[0098] It should be noted that the first connection end 401, the second connection end 402 and the mounting plate 403 can be an integral setting or a detachable connection setting, which is not limited here. For the sake of ease of understanding, the first connection end 401, the second connection end 402 and the mounting plate 403 of the embodiment of the present invention are an integral setting.

[0099] Preferably, the mounting plate 403 is fixedly connected to the bottom of the cylindrical sleeve 104 via a plurality of bolt mechanisms 404. This connection method not only provides structural stability, but also allows the connection mechanism to be disassembled and maintained when necessary.

[0100] The first connection end 401 penetrates the bottom of the cylindrical sleeve 104, and transmits microwave energy directly from the connection mechanism to the columnar portion 201 of the inner conductor 200. The mounting plate 403 and the second connection end 402 are arranged on the outside of the cylindrical sleeve 104, which helps to protect the microwave source connection mechanism 400 from the direct influence of the plasma generation area, and also facilitates the monitoring and maintenance of the operator, and ensures the stability and sealing of the microwave source connection mechanism 400.

[0101] In this embodiment, the number of bolt mechanisms 404 is not limited here, and the shape of the mounting plate 403 is not limited here, as long as sufficient installation stability and sealing effects can be achieved. For example, the mounting plate is a rectangular thin plate, and four bolt mechanisms 404 are provided, respectively arranged on the four right-angle sides of the rectangular thin plate.

[0102] Furthermore, an air intake assembly 500 is provided at the bottom of the cylindrical sleeve 104, and the air intake assembly 500 is connected to the cylindrical cavity 101. The air intake assembly 500 is arranged to be connected to the air source pipeline at its outer side, and to transport the air source in the air source pipeline into the cylindrical cavity 101. Figure 4 As shown, the flow direction of the gas source delivered by the gas inlet assembly 500 entering the cylindrical cavity 101 for the first time is horizontal.

[0103] Specifically, the air intake assembly 500 is arranged at the bottom of the cylindrical sleeve 104, which is conducive to the introduction and distribution of the gas source. The air intake assembly 500 is directly connected to the cylindrical cavity 101 to ensure that the gas source can smoothly enter and fill the cavity. The outer side of the air intake assembly 500 is connected to the gas source pipeline.

[0104] Exemplarily, the gas source pipeline is a connecting pipe 501 as shown in the figure. The gas source first enters the air intake assembly 500 from the connecting pipe 501 and is then transported to the cylindrical cavity 101. A mounting hole 502 can be provided at the bottom of the cylindrical sleeve 104 for easy connection with the connecting pipe 501.

[0105] In the embodiment of the present invention, preferably, the flow direction of the gas source delivered by the gas inlet assembly 500 when it first enters the cylindrical cavity 101 is horizontal, and the gas source forms a uniform gas flow in the cavity, providing a uniform gas distribution for the generation of plasma. Of course, the gas inlet assembly 500 may also include a valve or other control mechanism for adjusting the flow and pressure of the gas source, thereby controlling the characteristics of the plasma, such as density and temperature. At the same time, the gas inlet assembly 500 may also be provided with a sealing ring and other components to ensure the sealing of the structure, to prevent gas leakage, and to ensure the safety and effective delivery of the gas source.

[0106] More preferably, in the embodiment of the present invention, a single gas inlet assembly 500 is arranged at the bottom of the cylindrical sleeve 104, so that the gas source enters the plasma generating device from the single gas inlet assembly 500 and is close to the input end of the microwave source connecting mechanism 400. In actual use, the gas pipeline and the cable of the microwave source can be bundled together to form a traction line, and the pipeline or cable will not be bent when arranged on the same side. This structure not only makes the device neater, but also facilitates the operator to move and position, thereby improving the convenience of operation.

[0107] Embodiment 4:

[0108] The difference from Example 3 is that a blocking mechanism 600 is provided to prevent magnetic leakage, and the blocking mechanism 600 and the conical sleeve 105 are preferably connected by a threaded structure.

[0109] Exemplarily, a blocking mechanism 600 is disposed above the outer conductor sleeve 100 , and the blocking mechanism 600 is configured to block microwaves from passing through the emitting hole 103 and allow gas to flow, thereby preventing microwave energy from leaking after exciting plasma.

[0110] Specifically, the blocking mechanism 600 is disposed above the outer conductor sleeve 100, close to the emitting hole 103, to ensure that after the plasma is excited, the microwave energy will not leak from the emitting hole 103. It is ensured that all the microwave energy is used to excite the plasma, rather than being lost to the environment uselessly. At the same time, the blocking mechanism 600 allows gas to flow, so that the plasma can be discharged smoothly from the emitting hole 103.

[0111] In some embodiments, the blocking mechanism 600 uses special materials, such as microwave absorbing materials or shielding materials, such as brass, to effectively prevent the propagation of microwaves, and contains a microporous structure or a specific pore setting, which can block microwave radiation but allow gas molecules to pass through.

[0112] Exemplarily, the blocking mechanism 600 includes four blocking blocks 601, there is a gap between two adjacent blocking blocks 601, the four blocking blocks 601 enclose a conical structure, the diameter of the conical structure gradually decreases from bottom to top, the conical structure is provided with a central channel 602, the central channel 602 is configured to connect the launch hole 103 and the external environment, and the central channel 602 is coaxially arranged with the launch hole 103.

[0113] In the embodiment of the present invention, there are gaps between two adjacent blocking blocks 601, which allow gas to flow while blocking microwaves from passing through. The size and shape of the gaps can be set according to actual needs and are not limited here, so as to ensure that gas can pass smoothly while microwaves are effectively blocked. The cone structure enclosed by the four blocking blocks 601 has a diameter that gradually decreases from bottom to top, which helps to enhance the stability of the structure and helps to guide the flow of gas.

[0114] The central channel 602 provided in the vertebral structure connects the emission hole 103 and the external environment, ensuring that the plasma or the gas that excites the plasma can be discharged smoothly through the emission hole 103. The central channel 602 is coaxially arranged with the emission hole 103, that is, the center line of the central channel 602 coincides with the center line of the emission hole 103. This structure helps to maintain the consistency and stability of the gas flow. In general, the barrier mechanism 600 ensures the efficiency and safety of the microwave cold plasma generator, while allowing for effective management of plasma and gas.

[0115] The device provided by the embodiment of the present invention is easy to assemble. For example, during installation, the cylindrical sleeve 104 is first assembled with the connecting pipe 501 and the microwave source connecting mechanism 400, and then the limiting gasket 301 is inserted into the columnar portion 201, and then the arrow portion 202 is fixed to the columnar portion 201 to fix the limiting gasket 301, so that the inner conductor 200 and the limiting gasket 301 are assembled into a whole, and the whole is placed in the cylindrical sleeve 104, so that the limiting gasket 301 is installed in the annular groove 106, that is, the coaxial limiting of the outer conductor sleeve 100 and the inner conductor 200 is achieved. Then, the cylindrical sleeve 104 is connected to the conical sleeve 105 by threads, and finally the blocking mechanism 600 is connected to the conical sleeve 105, and the microwave plasma generating device of the embodiment of the present invention is assembled. The embodiment of the present invention can assemble or disassemble the barrier according to the use requirements. The specific structure of the barrier is not limited to the above structure, and other existing barrier structures can be used for implementation, which is not limited here. The assembled structure is as follows: Figure 2-Figure 4 shown.

[0116] When working, connect the microwave source connection mechanism 400 to the microwave source, then inject the gas from the air inlet assembly 500, and turn on the microwave source switch. The microwave energy is focused on the tip 205 of the coaxial terminal, so that the electric field strength here is relatively high, and the output power of the microwave source is adjusted. When it reaches a certain preset value, the electric field strength at the tip 205 breaks through the nearby gas to generate plasma. Because the embodiment of the present invention uses a conical cavity and an arrowhead-shaped inner conductor 200 to excite plasma, the microwave power required for excitation is relatively low, so the temperature of the generated plasma is relatively low. It should be noted that the gas introduced can be argon, air, oxygen, nitrogen, helium and other gases, which are not limited here and can be set according to actual needs.

[0117] The plasma generator in Example 4 was tested, wherein the input microwave power was 20 W. The test results are as follows: Figure 7-Figure 10 As shown. Among them, Figure 7 Schematic diagram of the distribution of the electric field of the microwave plasma torch outside the cylindrical cavity 101 and the conical cavity 102. Figure 8 Schematic diagram of the distribution of the electric field of the microwave plasma torch in the cylindrical cavity 101 and the conical cavity 102. Fig. 9 It is a partial enlarged front view of the distribution of the electric field of the microwave plasma torch at the tip 205, Fig.10 It is a top view of the local enlarged distribution of the electric field of the microwave plasma torch at the tip 205. It can be seen that the field strength is strongest between the tip 205 and the upper end of the conical sleeve 105, which can reach up to 106V / m, and can self-excite argon gas; and the field strength is evenly distributed with the center of the emitting hole 103 as the symmetrical center, and can generate plasma symmetrical with the axial direction of the inner conductor 200.

[0118] In order to more clearly demonstrate the advantages of the microwave cold plasma generating device provided by the embodiment of the present invention compared with the prior art, the device will be tested next, as shown in the following embodiment 5:

[0119] Embodiment 5:

[0120] On the basis of Example 4, the lower external connection portion 203 of the columnar portion 201 of the inner conductor 200 is set to a cylinder with a diameter of 3 mm, the microwave source connection mechanism 400 is set to an N-type head, and the diameter of the first connection end 401 of the N-type head is 1.27 mm, and the cylindrical sleeve 104 is threadedly connected to the conical sleeve 105, so that it is convenient to replace different conical sleeves 105 according to needs. The conical sleeve 105 is threadedly connected to the blocking mechanism 600, and the blocking mechanism 600 can be replaced or cancelled according to the length of the plasma jet after excitation or the actual application position.

[0121] In an embodiment of the present invention, the gas introduced is pure argon, and the N-type head is connected to the microwave source through a cable. The microwave source is a magnetron. Of course, in other embodiments, it can also be a traveling wave tube, a beam modulator, a solid-state source, etc.

[0122] It should be noted that the microwave frequency can be any frequency point in the electromagnetic wave, such as 915MHz, 2450MHz, 5800MHz, etc. The length of the coaxial structure can be increased or decreased according to the actual use requirements, so that the field intensity at the tip of the conductor 200 in the device can reach the maximum at different frequencies. The microwave power can be adjusted, that is, the microwave power can be adjusted according to the type of gas passed, or different microwave powers can be used for the same gas to obtain plasmas of different properties, and the gas flow rate can also be adjusted. For example, when argon gas is passed, the microwave power can be adjusted to obtain a plasma jet length range of 2-13.5mm.

[0123] Back to the embodiment of the present invention, the plasma generated by the device is used to treat facial skin to achieve the purpose of anti-aging and promoting skin firming. When in use, the excited argon gas is passed from the gas cylinder into the gas inlet assembly 500. When the gas fills the cylindrical cavity 101 and the conical cavity 102, the microwave source is started and the microwave output power is adjusted. A high field strength is generated at the tip 205, breaking down the argon gas for gas discharge and forming an argon plasma jet. When the microwave input power is 4.5W and the argon flow rate is 8.6L / min, the hand is placed at the end of the plasma jet for 30s, and the finger temperature rises to 36.8°C, without heat or pain.

[0124] The barrier of the device is placed on the human facial skin, and the end of the plasma jet hits the skin. The active free radicals and high-speed particles generated by the plasma act on the skin, stimulating the activity of the surface skin and restoring the skin to a beautiful and youthful state.

[0125] In the embodiment of the present invention, the argon plasma effect is actually produced. When the microwave power of the 2.45GHz microwave input is 6.16W and the argon flow rate is 2.5L / min, the length of the argon plasma is 13.5mm. When the argon flow rate is 0.9L / min, the minimum microwave maintenance power is 1.57W, and the plasma jet length at this time is 2mm. When the microwave input power is 8W and the argon flow rate range is 0.3L / min-30L / min, the plasma can be maintained. Regarding safety issues, the device is connected to a microwave source. After the plasma is excited, the microwave leakage is tested at various points at the device port. The data obtained by monitoring is up to 190μW / cm 2 Therefore, there is almost no leakage of microwaves in the plasma generating device provided in the embodiment of the present invention.

[0126] Microwave low-temperature plasma can increase the excitation, ionization, and dissociation process of gas molecules, and excite more substate atoms. Its degree of ionization and dissociation of gas is one order of magnitude higher than other types of plasma, such as radio frequency electric field plasma; and the plasma has high density, high ionization degree, high energy, strong activity, and is more likely to cause or trigger related physical and chemical reactions. Therefore, it is more efficient in medical treatments that rely on plasma active components. The plasma generated by the device provided in the embodiment of the present invention has a higher electron temperature and electron density than the active particles generated by the prior art, so the application effect is more obvious.

[0127] In general, in the structure of a traditional coaxial microwave plasma torch, the tip 205 is usually flush with the terminal of the conical sleeve 105, but in the embodiment of the present invention, the terminal of the tip 205 is not flush with the terminal of the conical sleeve 105, but is arranged so that the terminal of the conical sleeve 105 is longer than the tip 205. This structure forms a conical cavity at the coaxial terminal, which can increase the electric field strength of the coaxial terminal, thereby facilitating the continuous excitation of plasma. The setting of the arrowhead-shaped structure enables the generation of a high electric field strength at the tip 205, which helps to self-excite the working gas to generate plasma at low power, thereby reducing energy consumption and improving efficiency, ensuring smooth gas circulation, and generating a high field strength at the tip, which not only helps to effectively utilize the gas, but also ensures the uniform generation of plasma. The setting of the barrier is similar to a cutoff waveguide, which effectively prevents microwave leakage and maintains high safety even after plasma excitation, so that the device can be directly placed on the surface of human skin for treatment without worrying about the risk of microwave radiation.

[0128] The device provided by the embodiment of the present invention can maintain the generation of plasma at extremely low power, as low as 1.57W, which not only improves the energy efficiency but also increases the stability of the device. The generated plasma contains a high concentration of hydroxyl radical active particles and high-energy particles, making its practical application effect better, especially in the fields of medical treatment and surface treatment.

[0129] At the same time, the device provided by the embodiment of the present invention has a compact and small structure, is easy to carry and assemble, and is easy to mass produce. The tip portion 205 of the inner conductor 200 and the conical sleeve 105 are detachable, so that the operator can replace the corresponding components according to different microwave source frequencies, which is suitable for the production of different types of gases and plasmas. The air intake assembly 500 is arranged adjacent to the microwave source connection mechanism 400, which is convenient for the operator to perform hand-held operation, and the air pipe and the cable can be tied tightly, further improving the convenience of use.

[0130] The device can use not only argon, but also air, oxygen, nitrogen, helium and other gases, which increases the flexibility of application. At the same time, different sizes of conical outer conductor sleeves and arrowhead-shaped inner conductors 200 can be replaced according to different microwave usage frequencies, so that the device can adapt to different application requirements. The microwave cold plasma generating device provided by the embodiment of the present invention has shown obvious advantages in improving plasma generation efficiency, reducing energy consumption, enhancing safety and improving operation convenience, and has high practical application value.

[0131] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0132] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the term "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device.

[0133] The above is a detailed introduction to a microwave cold plasma generating device based on a coaxial arrowhead-shaped structure provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application, and the content of this specification should not be understood as a limitation on the present application. At the same time, for those of ordinary skill in the art, according to the present application, there will be different forms of changes in the specific implementation methods and application scopes. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present application.

Claims

1. A microwave cold plasma generating device based on a coaxial arrowhead-shaped structure, characterized in that: include: An outer conductor sleeve (100) is provided as a peripheral structure of a plasma generation region, and includes a cylindrical cavity (101) and a conical cavity (102) which are connected to each other. The outer conductor sleeve (100) can be connected to a gas source. An inner conductor (200) is arranged inside the outer conductor sleeve (100) and is coaxially arranged with the outer conductor sleeve (100), an annular gap is formed between the inner conductor (200) and the outer conductor sleeve (100), and the inner conductor (200) is used to transmit microwave energy to the conical cavity (102) region; The inner conductor (200) comprises a columnar portion (201) and an arrow portion (202); one end of the columnar portion (201) is connected to a microwave source, and the other end is connected to a side opposite to the tip of the arrow portion (202); the columnar portion (201) is used to transmit microwave energy from the microwave source to the arrow portion (202); The columnar portion (201) is located in the columnar cavity (101), and the arrow portion (202) is located in the conical cavity (102); The tip of the arrow portion (202) is arranged at the tip side of the conical cavity (102); an emitting hole (103) is arranged on the outer conductor sleeve (100) at the tip side of the conical cavity (102); the tip end surface of the arrow portion (202) is lower than the end surface of the emitting hole (103); and the emitting hole (103) is arranged to emit the cold plasma into the external environment of the outer conductor sleeve (100); The conical cavity (102) is configured to converge the electric field in the microwave energy at the tip of the arrow portion (202), thereby increasing the electric field intensity at the tip of the arrow portion (202), thereby achieving self-ignition to excite the gas source to generate plasma.

2. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 1, characterized in that: The outer conductor sleeve (100) comprises a cylindrical sleeve (104) and a conical sleeve (105), the cylindrical cavity (101) is located in the cylindrical sleeve (104), the conical cavity (102) is located in the conical sleeve (105), and the top of the cylindrical sleeve (104) is detachably connected to the bottom of the conical sleeve (105); The diameter of the cylindrical cavity (101) is equal to the maximum diameter of the conical cavity (102).

3. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 2, characterized in that: A limiting mechanism (300) is arranged inside the outer conductor sleeve (100), and the limiting mechanism (300) is arranged to limit the inner conductor (200) and the outer conductor sleeve (100) coaxially.

4. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 3, characterized in that: An annular groove (106) is arranged in the cylindrical sleeve (104); the limiting mechanism (300) is a limiting gasket (301); the limiting gasket (301) is arranged in the annular groove (106); and the limiting gasket (301) is coaxially arranged with the outer conductor sleeve (100); A through hole (302) is provided at the center of the limiting gasket (301), the columnar portion (201) passes through the through hole (302), and the arrow portion (202) is located above the limiting gasket (301); a plurality of ventilation holes (303) are provided on the limiting gasket (301), and the ventilation holes (303) are used to circulate the air source in the cavity below the limiting gasket (301) to the cavity above the limiting gasket (301).

5. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 4, characterized in that: The columnar portion (201) comprises a lower externally connected portion (203) and an upper internally connected portion (204) which are axially connected, the lower externally connected portion (203) is connected to a microwave source connection mechanism (400), and the diameter of the through hole (302) is greater than the diameter of the upper internally connected portion (204) and smaller than the outer diameter of the lower externally connected portion (203); The arrow portion (202) comprises an axially connected tip portion (205) and a connecting portion (206); the connecting portion (206) is a hollow structure opening downward, and the upper inscribed portion (204) of the columnar portion (201) can be inserted into the hollow structure; The upper internal connection portion (204) is configured to penetrate the through hole (302) and then be inserted into the hollow structure, so as to fix the limiting gasket (301) at the connection between the columnar portion (201) and the arrow portion (202); The outer diameter of the connecting portion (206) is greater than the diameter of the through hole (302).

6. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 5, characterized in that: When the limiting gasket (301) is fixed at the connection between the columnar portion (201) and the arrow portion (202), the upper end surface of the lower external connection portion (203) fits with the bottom of the limiting gasket (301), and the lower end surface of the connection portion (206) fits with the upper end of the limiting gasket (301); The upper internal connection portion (204) is threadedly connected to the connection portion (206).

7. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 5, characterized in that: The microwave source connection mechanism (400) comprises a first connection end (401) and a second connection end (402), a mounting plate (403) is provided between the first connection end (401) and the second connection end (402), and the mounting plate (403) is fixedly connected to the bottom of the cylindrical sleeve (104) via a plurality of bolt mechanisms (404); The first connection end (401) passes through the bottom of the cylindrical sleeve (104) and is connected to the lower external connection portion (203) of the columnar portion (201); the mounting plate (403) and the second connection end (402) are arranged on the outside of the cylindrical sleeve (104); and the second connection end (402) is used to connect to a microwave source.

8. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 7, characterized in that: An air intake assembly (500) is provided at the bottom of the cylindrical sleeve (104), the air intake assembly (500) is connected to the cylindrical cavity (101), and the air intake assembly (500) is arranged to be connected to an air source pipeline at its outer side and to transport the air source in the air source pipeline into the cylindrical cavity (101); The flow direction of the gas source delivered by the gas inlet assembly (500) entering the cylindrical cavity (101) for the first time is horizontal.

9. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 1, characterized in that: A blocking mechanism (600) is arranged above the outer conductor sleeve (100), and the blocking mechanism (600) is arranged to block microwaves from passing through the emission hole (103) and allow gas to flow, thereby preventing microwave energy from leaking after exciting plasma.

10. The microwave cold plasma generating device based on a coaxial arrowhead-shaped structure according to claim 9, characterized in that: The blocking mechanism (600) comprises four blocking blocks (601), a gap exists between two adjacent blocking blocks (601), the four blocking blocks (601) enclose a vertebral structure, the diameter of the vertebral structure gradually decreases from bottom to top, the vertebral structure is provided with a central channel (602), the central channel (602) is arranged to connect the launch hole (103) and the external environment, and the central channel (602) is coaxially arranged with the launch hole (103).

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