An arc plasma generator

Abstract

The present invention provides an arc plasma generator, which relates to the technical field of plasma generators. The arc plasma generator provided by the present invention includes a cathode, an insulating support assembly, an intermediate member, an air inlet member, an insulating member, and an anode; the cathode is connected to the top of the insulating support assembly; the intermediate member, the air inlet member, the insulating member, and the anode are clamped on the insulating support assembly from top to bottom. The intermediate member has a first plasma channel, the cathode penetrates through the top of the insulating support assembly and extends into the first plasma channel, and the anode has a second plasma channel that communicates with the first plasma channel through the air inlet member and the insulating member. The air inlet member is used to distribute the protective gas into the second plasma channel and form a spiral protective gas on the surface of the second plasma channel. The above-mentioned arc plasma generator can increase the arc voltage and reduce the arc current, can confine the plasma jet and improve the characteristics of the plasma in the arc root attachment area, stabilize the arc and inhibit electrode ablation.

Description

Technical Field

[0001] The invention relates to the technical field of plasma generators, and in particular to an arc plasma generator. Background Art

[0002] An arc plasma generator is a device that generates high-temperature plasma through discharge between electrodes. Under normal circumstances, the discharge between electrodes can form a high temperature of more than 10,000 degrees, and the temperature of the plasma jet generated is also more than 1,000 degrees. Therefore, DC arc plasma generators are usually used as high-temperature heat sources in various scenarios. For example, high-temperature arcs can melt metal and ceramic powders for the preparation of various functional coatings, can also be used for waste treatment in the field of environmental protection, can also be used for ultrafine powder synthesis, cutting, and even smelting steel, etc., and have very wide applications in various fields.

[0003] At present, there are two prominent problems in the practical application of arc plasma generators: the first is the instability caused by the arc root jumping along the axial direction, which affects the production process; the second is the anode ablation caused by the arc root agglomerating and adhering to the electrode surface, which not only affects the production process, but also directly determines the service life of the generator. Therefore, studying the principle of electrode ablation inside the arc plasma generator and proposing a new solution to reduce electrode ablation are of great significance to improving the production process and service life of the arc plasma generator.

[0004] In most plasma generators, the main cause of anode ablation is local overheating at high temperatures for a long time. The main cause of local overheating at high temperatures for a long time is that the arc root adheres stably to a fixed position on the electrode surface for a long time, resulting in a high concentration of Joule heat. As is well known, Joule heat is proportional to the square of the current. As long as the arc current can be reduced, Joule heat can be greatly reduced, electrode ablation can be alleviated, and the service life of the generator can be extended. The input power is equal to the voltage multiplied by the current. When the rated power of the plasma generator is constant, we can increase the arc voltage to reduce the arc current. Currently, the widely used methods to increase the arc voltage include: adding an intermediate section with a floating potential between the electrodes, multi-stage air intake to blow and draw the arc, and segmented anode structure. Another method to alleviate electrode ablation is to avoid the arc adhering to a fixed area on the electrode surface for a long time. By making the arc rotate circumferentially on the electrode surface, the heating area of the anode can be increased. Currently, the main ways to make the arc rotate circumferentially on the electrode surface include: magnetic rotating arc, that is, by applying a current-carrying solenoid outside the arc plasma generator, and driving the arc to rotate circumferentially along the electrode surface under the action of the magnetic field of the current-carrying solenoid. However, this method not only requires adding a solenoid, but also requires applying direct current to it to generate a magnetic field. If the required magnetic field strength is large, a supporting cooling device needs to be added to the current-carrying solenoid. Therefore, the magnetic rotating arc greatly increases the complexity and unreliability of the plasma generator system. Summary of the Invention

[0005] The purpose of the present invention is to provide an arc plasma generator that can increase the arc voltage, reduce the arc current, and can constrain the plasma jet and improve the characteristics of the plasma in the arc root attachment area, stabilize the arc, and inhibit electrode ablation.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides an arc plasma generator, including a cathode, an insulating support assembly, an intermediate member, an air intake member, an insulating member, and an anode;

[0008] The cathode is connected to the top of the insulating support assembly;

[0009] The intermediate member, the air intake member, the insulating member, and the anode are clamped on the insulating support assembly from top to bottom. The intermediate member has a first plasma channel. The cathode penetrates the top of the insulating support assembly and extends into the first plasma channel and is used to fill the first plasma channel with working gas. The anode has a second plasma channel. The second plasma channel is communicated with the first plasma channel through the air intake member and the insulating member. The air intake member is used to distribute the protective gas into the second plasma channel and form a spiral protective gas on the surface of the second plasma channel.

[0010] Further, the cathode includes an upper substrate, a middle part of the cathode, and a lower tip. The upper substrate is connected to the top end of the insulating support assembly. The upper substrate has at least one working gas inlet communicating with the first plasma channel. One end of the middle part of the cathode is fixedly connected to the upper substrate, and the other end is clamped with the lower tip. The lower tip is located in the first plasma channel.

[0011] A cooling cavity is provided in the middle part of the cathode. The upper substrate has a cooling working medium inlet channel and a cooling working medium discharge channel communicating with the cooling cavity.

[0012] Further, the insulating support assembly includes a top insulating layer, a bottom insulating layer, a bottom support member, and a locking member. The top insulating layer is connected to the bottom support member through the locking member to clamp the intermediate member, the air inlet member, the insulating member, and the anode between the top insulating layer and the bottom support member. The bottom insulating layer is installed on a side of the bottom support member facing the top insulating layer.

[0013] Further, the first plasma channel includes an air inlet area and a discharge area. Two ends of the discharge area are respectively communicated with the air inlet area and the second plasma channel. One end of the air inlet area close to the discharge area gradually decreases in diameter along the air inlet direction.

[0014] Further, the second plasma channel includes an expansion section, a sudden expansion straight cylinder section, and a contraction beam section that are sequentially communicated from top to bottom. The expansion section gradually increases in diameter along the direction of gradually approaching the sudden expansion straight cylinder section. The diameter of the sudden expansion straight cylinder section is larger than the diameter at any place of the expansion section and forms a sudden expansion shoulder with the expansion section. The contraction beam section gradually decreases in diameter along the direction of gradually departing from the sudden expansion straight cylinder section.

[0015] Further, a gas distribution cavity is formed between the air inlet member and the intermediate member. A side wall of the air inlet member has an air inlet channel communicating with the gas distribution cavity for introducing the protective gas. The air inlet member is provided with a first protective gas channel. Two ends of the first protective gas channel are respectively communicated with the gas distribution cavity and one end of the expansion section departing from the sudden expansion straight cylinder section.

[0016] The first protective gas channel is inclined, and an axis of the first protective gas channel is skew to an axis of the expansion section, so that the protective gas discharged from the first protective gas channel forms a spiral air flow in the expansion section.

[0017] Further, an air inlet hole communicating with the air distribution cavity is also formed in the air inlet member, a ventilation hole is formed in the insulating member, and an exhaust hole is formed in the anode. The exhaust hole extends from the top surface of the anode to the sudden expansion shoulder. The air inlet hole, the ventilation hole, and the exhaust hole are sequentially communicated to form a second protective gas channel.

[0018] Further, the exhaust hole is obliquely arranged, and the axis of the exhaust hole is skew to the axis of the sudden expansion straight cylinder section, so that the protective gas discharged from the second protective gas channel forms a spiral air flow in the sudden expansion straight cylinder section.

[0019] Further, a first cooling sleeve and a second cooling sleeve are further included;

[0020] The first cooling sleeve is sleeved outside the intermediate member and forms a first cooling cavity between the first cooling sleeve and the intermediate member;

[0021] The second cooling sleeve is sleeved outside the anode and forms a second cooling cavity between the second cooling sleeve and the anode;

[0022] The air inlet member is clamped between the first cooling sleeve and the second cooling sleeve, and a cooling working medium guide through hole communicating the first cooling cavity and the second cooling cavity is provided on the air inlet member.

[0023] Further, a first cooling channel with both ends communicating with the first cooling cavity is arranged in the intermediate member. One end of the first cooling channel is higher than the other end, and the caliber of one end is larger than that of the other end;

[0024] A second cooling channel with both ends communicating with the second cooling cavity is arranged in the anode. One end of the second cooling channel is higher than the other end, and the caliber of one end is larger than that of the other end.

[0025] When the above arc plasma generator is used, the working medium gas enters the first plasma channel from the cathode, and then enters the second plasma channel through the air inlet member and the insulating member. An arc plasma jet is generated between the cathode and the anode, and the plasma finally flows out from the second plasma channel. The protective gas enters the second plasma channel through the distribution spiral of the air inlet member, forms a gas film to confine the arc plasma and protect the anode.

[0026] Compared with the prior art, the arc plasma generator provided by the present invention has the following advantages:

[0027] 1. By adding an intermediate member to lengthen the arc, increasing the arc voltage and reducing the arc current;

[0028] 2. The intake component can distribute the protective gas into the second plasma channel to form a gas film within the second plasma channel, thereby effectively constraining the plasma jet and improving the characteristics of the plasma in the arc root attachment region, stabilizing the arc and suppressing electrode ablation, thus increasing the service life of the plasma generator.

[0029] 3. It has a relatively simple structure and can effectively suppress electrode ablation and extend the service life without introducing additional devices. Description of the Drawings

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following-described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 A cross-sectional view of an arc plasma generator provided by an embodiment of the present invention;

[0032] Figure 2 A top view of an arc plasma generator provided by an embodiment of the present invention;

[0033] Figure 3 For Figure 2 the A-A cross-sectional view;

[0034] Figure 4 A longitudinal cross-sectional view of the anode provided by an embodiment of the present invention;

[0035] Figure 5 A perspective view of the anode provided by an embodiment of the present invention;

[0036] Figure 6 A top view of the anode provided by an embodiment of the present invention;

[0037] Figure 7 For Figure 1 the enlarged view at B;

[0038] Figure 8 A three-dimensional structure diagram of an intake component provided by an embodiment of the present invention;

[0039] Figure 9 A perspective view of an insulating component provided by an embodiment of the present invention.

[0040] Icon: 1 - cathode; 11 - upper substrate; 111 - working medium gas inlet; 112 - cooling working medium inlet channel; 113 - cooling working medium discharge channel; 12 - middle part of cathode; 121 - cooling cavity; 13 - lower tip; 14 - screw; 2 - insulating support assembly; 21 - top insulating layer; 22 - bottom insulating layer; 23 - bottom support; 24 - locking part; 3 - intermediate part; 31 - first plasma channel; 311 - air inlet area; 312 - discharge area; 32 - first cooling channel; 33 - protruding part; 4 - air inlet part; 41 - air inlet channel; 42 - first protective gas channel; 43 - air inlet hole; 44 - cooling working medium guiding through hole; 5 - insulating part; 51 - ventilation hole; 6 - anode; 61 - second plasma channel; 611 - expansion section; 612 - sudden expansion straight tube section; 613 - contraction beam section; 614 - sudden expansion shoulder; 62 - exhaust hole; 63 - second cooling channel; 7 - gas distribution cavity; 8 - first cooling sleeve; 81 - cooling working medium outlet; 9 - second cooling sleeve; 91 - cooling working medium inlet. Detailed implementation manner

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It 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 should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0044] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0045] This embodiment aims to provide an arc plasma generator, as Figure 1 shown, which includes a cathode 1, an insulating support assembly 2, an intermediate member 3, an air inlet member 4, an insulating member 5, and an anode 6; the cathode 1 is connected to the top end of the insulating support assembly 2; the intermediate member 3, the air inlet member 4, the insulating member 5, and the anode 6 are clamped on the insulating support assembly 2 from top to bottom. The intermediate member 3 has a first plasma channel 31. The cathode 1 penetrates through the top end of the insulating support assembly 2 and extends into the first plasma channel 31 for filling a working gas into the first plasma channel 31. The anode 6 has a second plasma channel 61. The second plasma channel 61 is communicated with the first plasma channel 31 through the air inlet member 4 and the insulating member 5. The air inlet member 4 is used for distributing a protective gas into the second plasma channel 61 and forming a spiral protective gas on the surface of the second plasma channel 61.

[0046] The following will be combined with Figure 3 to briefly describe the working process of the above arc plasma generator:

[0047] The working gas enters the first plasma channel 31 through the cathode 1 and forms a plasma, and then enters the second plasma channel 61 through the air inlet member 4 and the insulating member 5, and finally flows out from the second plasma channel 61. The protective gas enters the second plasma channel 61 through the air inlet member 4 and forms a spiral protective gas on the surface of the second plasma channel 61 to confine the arc plasma and protect the anode 6.

[0048] In a DC arc plasma generator, generally relatively inexpensive nitrogen and air are used as plasma-forming gases (working gases). Taking nitrogen as an example, the enthalpy value of the nitrogen arc is relatively high, and the anode arc root is very concentrated. Directly attaching to the surface of the anode 6 often causes serious electrode erosion due to excessive current density and heat flux density, shortening the service life of the equipment. By injecting an inert gas protective gas such as argon into the anode 6 from the air inlet member 4, a protective gas layer is formed in the near-electrode region. The physical properties of the protective gas are not easily contracted compared to working gases such as nitrogen, and the generated plasma expands relatively. The nitrogen arc root will pass through the protective gas layer before attaching to the surface of the anode 6, ionize the protective gas in the protective gas layer, form a relatively mild arc root, thereby improving the characteristics of the arc plasma in the anode arc root attachment region, increasing the attachment area of the arc root, reducing the heat flux density flowing to the anode 6, and thus suppressing electrode erosion and prolonging the service life of the arc plasma generator.

[0049] The following will specifically describe the structure of the cathode 1:

[0050] In some embodiments, as Figures 1 to 3 shown, the cathode 1 includes an upper substrate 11, a middle cathode portion 12, and a lower tip 13.

[0051] Among them, the upper substrate 11 is connected to the top end of the insulating support assembly 2. Specifically, the upper substrate 11 can be in the shape of a circular plate structure, and the upper substrate 11 is connected to the insulating support assembly 2 through a plurality of screws. The screws can be configured as two, three, four, etc., and are preferably configured as four, and the four screws are evenly distributed around the axis of the upper substrate 11. The upper substrate 11 has at least one working medium gas inlet 111 communicating with the first plasma channel 31, and the working medium gas can enter the first plasma channel 31 from the working medium gas inlet 111. Preferably, two inlet pipes are connected to the upper substrate 11, and each of the two inlet pipes has a working medium gas inlet 111.

[0052] Among them, one end of the middle cathode portion 12 is fixedly connected to the upper substrate 11, and the other end is snap-fitted with the lower tip 13, and the lower tip 13 is located in the first plasma channel 31. Specifically, the middle cathode portion 12 is in the shape of a pencil tip, and the end with a larger diameter of the middle cathode portion 12 and the upper substrate 11 are fixed by welding; the lower tip 13 is in the shape of a sharp cone, and the lower tip 13 is snap-fitted inside the other end of the middle cathode portion 12 through interference fit.

[0053] The materials of the upper substrate 11 and the middle cathode portion 12 are preferably red copper, and the lower tip 13 is made of a high-temperature resistant material, preferably tungsten, hafnium, etc.

[0054] On the basis of the above embodiments, in some embodiments, to avoid the temperature of the cathode 1 being too high during operation, as Figure 1 shown, a cooling cavity 121 is provided inside the middle cathode portion 12, and the upper substrate 11 has a cooling working medium inlet channel 112 and a cooling working medium discharge channel 113 communicating with the cooling cavity 121.

[0055] The cooling working medium can enter the cooling cavity 121 from the cooling working medium inlet channel 112 and discharge from the cooling working medium discharge channel 113, taking away the heat of the middle cathode portion 12, and thus playing a role in cooling the lower tip 13.

[0056] Specifically, the cooling cavity 121 is opened in the middle of the middle cathode portion 12 facing the upper substrate 11. A first through hole is opened in the middle of the upper substrate 11, and a second through hole is opened beside the first through hole. A liquid inlet pipe communicating with the cooling cavity 121 is inserted into the first through hole, and the liquid inlet pipe forms the cooling working medium inlet channel 112. A liquid outlet pipe communicating with the cooling cavity 121 is inserted into the second through hole, and the liquid outlet pipe forms the cooling working medium discharge channel 113.

[0057] As Figure 1As shown, in order to facilitate the connection between the liquid inlet pipe and the liquid outlet pipe, the cooling cavity 121 includes a cylindrical cavity coaxial with the upper substrate 11 and a side cavity communicating with one side of the cylindrical cavity. The liquid inlet pipe extends into the cylindrical cavity, and the liquid outlet pipe is directly communicated with the side cavity.

[0058] The following is a specific description of the insulating support assembly 2:

[0059] In some embodiments, as Figure 1 shown, the insulating support assembly 2 includes a top insulating layer 21, a bottom insulating layer 22, a bottom support 23 and a locking member 24. The top insulating layer 21 is connected to the bottom support 23 through the locking member 24, and the bottom insulating layer 22 is installed on one side of the bottom support 23 facing the top insulating layer 21. The above-mentioned insulating support assembly 2 has a simple structure and can effectively limit the axial positions of the intermediate member 3, the air inlet member 4, the insulating member 5 and the anode 6.

[0060] Among them, the locking member 24 can adopt various structures. For example, the locking member 24 includes a screw and a nut, or the locking member includes snap-fasteners that are snap-connected to each other. That is, any structure that can connect the top insulating layer 21 and the bottom support 23 can be the locking member 24 mentioned in the above embodiments.

[0061] In at least one embodiment, as Figure 1 shown, the locking member 24 includes a screw and a nut. The top insulating layer 21 is provided with a plurality of insertion holes, and the bottom support 23 is provided with stepped counterbores corresponding to the positions of the insertion holes. The screw passes through the insertion holes and the stepped counterbores, and the limiting head at the bottom end of the screw is accommodated in the stepped counterbore, and the nut is screwed on the top end of the screw. After tightening the nut, the intermediate member 3, the air inlet member 4, the insulating member 5 and the anode 6 are clamped between the top insulating layer 21 and the bottom support 23.

[0062] Specifically, a stepped through hole is formed in the middle of the bottom support 23, and the bottom end of the anode 6 is accommodated in the stepped through hole, and a sealing ring is clamped between the anode 6 and the stepped through hole to ensure good sealing between the two.

[0063] In addition, the top insulating layer 21 and the bottom insulating layer 22 are made of insulating materials such as polytetrafluoroethylene and ceramics.

[0064] To facilitate the positioning of the bottom insulating layer 22, an installation groove is formed on one side of the bottom support 23 facing the top insulating layer 21, and the bottom insulating layer 22 is installed in the installation groove. When a cooling structure is sleeved outside the anode 6, the setting of the bottom insulating layer 22 can play a role in electrically insulating the anode 6 and the cooling structure. Therefore, when there is no cooling structure sleeved outside the anode 6, the bottom insulating layer 22 may not be provided either.

[0065] The following is a specific description of the structure of the intermediate member 3:

[0066] In some embodiments, as Figure 3 shown, the first plasma channel 31 includes an air inlet area 311 and a discharge area 312. Both ends of the discharge area 312 are respectively communicated with the air inlet area 311 and the second plasma channel 61.

[0067] Since the end of the cathode extending into the air inlet area 311 is in a tapered shape, in order to make the shape of the air inlet area 311 adapt to the cathode 1, the diameter of the end of the air inlet area 311 close to the discharge area 312 gradually decreases along the air inlet direction. At the same time, it can play a guiding role in the air inlet, ensuring that the air inlet can smoothly and quickly enter the discharge area 312 and avoiding the occurrence of an air inlet retention area.

[0068] As Figure 3 shown, the discharge area 312 can be in a cylindrical shape.

[0069] Specifically, the middle piece 3 is in a columnar structure, and the material is preferably copper or tungsten. As Figure 3 shown, the middle of the end of the middle piece 3 facing away from the cathode 1 has a convex portion 33. A first air hole is opened in the middle of the air inlet piece 4. The convex portion 33 extends into the first air hole of the air inlet piece 4 and there is a gap between the convex portion 33 and the surface of the first air hole.

[0070] In order to avoid the temperature of the middle piece 3 being too high during operation, as Figure 3 shown, a first cooling channel 32 is provided in the middle piece 3. The coolant can enter and exit the middle piece 3 through the first cooling channel 32, thereby realizing the function of cooling the middle piece 3.

[0071] The first cooling channel 32 can be configured as one, or can be configured as two, three or more. When the first cooling channel 32 is configured as multiple, each of the first cooling channels 32 can intersect completely or partially, and each of the first cooling channels 32 can also not intersect.

[0072] In some embodiments, the first cooling channel 32 extends in a straight line, and one end of the first cooling channel 32 is higher than the other end to increase the contact area between the first cooling channel 32 and the middle piece 3. The diameter of one end of the first cooling channel 32 can be larger than the diameter of the other end, so that the cooling working medium has a tendency to flow from the end with a smaller opening to the end with a larger opening, promoting the flow of the cooling working medium.

[0073] It should be noted that the above height direction can be regarded as the direction parallel to the axial direction of the middle piece 3, and the end close to the cathode 1 is the high end.

[0074] In at least one embodiment, the opening of the first cooling channel 32 at the lower end is smaller than the opening at the upper end.

[0075] The structure of the anode 6 is specifically described as follows:

[0076] In some embodiments, as Figure 4 shown, the second plasma channel 61 includes a diverging section 611, a sudden-expansion straight section 612, and a converging beam section 613 that are connected in sequence from top to bottom. The diverging section 611 has a gradually increasing diameter in the direction approaching the sudden-expansion straight section 612. The diameter of the sudden-expansion straight section 612 is larger than the diameter at any point of the diverging section 611 and forms a sudden-expansion shoulder 614 facing the sudden-expansion straight section 612 with the diverging section 611. The converging beam section 613 has a gradually decreasing diameter in the direction away from the sudden-expansion straight section 612.

[0077] During use, first, an arc plasma jet is generated between the cathode 1 and the anode 6 by activating the auxiliary arc-starting circuit. Subsequently, the auxiliary arc-starting circuit is disconnected. The plasma jet expands and accelerates through the diverging section 611 above the anode 6, and the arc root adheres to the sudden-expansion straight section 612 under the action of aerodynamic force, and finally flows out from the tail converging beam section 613.

[0078] Specifically, the anode 6 is made of a conductive and highly thermally conductive material, preferably copper.

[0079] To avoid the temperature of the anode 6 being too high during operation, as Figure 5 shown, a second cooling channel 63 is provided in the anode 6. The coolant can enter and exit the anode 6 through the second cooling channel 63, thereby cooling the anode 6.

[0080] The second cooling channel 63 can be configured as one, or can be configured as multiple ones such as two, three, four, etc.

[0081] Taking Figure 5 as an example for specific illustration, the second cooling channel 63 is configured as four, and the four second cooling channels 63 are arranged in parallel. Among the four second cooling channels 63, two are distributed on one side of the second plasma channel 61, and the other two are distributed on the other side of the second plasma channel 61.

[0082] In some embodiments, similar to the first cooling channel 32, the second cooling channel 63 extends linearly, and one end of the second cooling channel 63 is higher than the other end to increase the contact area between the second cooling channel 63 and the anode 6. The diameter of one end of the second cooling channel 63 can be larger than the diameter of the other end, so that the cooling working medium has a tendency to flow from the end with a smaller opening to the end with a larger opening, promoting the flow of the cooling working medium.

[0083] It should be noted that the above height direction can be regarded as the direction parallel to the axial direction of the anode 6, and the end close to the cathode 1 is the higher end.

[0084] In at least one embodiment, as Figure 5 shown, the opening at the lower end of the second cooling channel 63 is smaller than the opening at the upper end.

[0085] The structure of the air intake member 4 is described in detail below:

[0086] The air inlet member 4 is made of conductive material, preferably copper which is easy to process.

[0087] In some embodiments, Figure 7 As shown, in order to facilitate the distribution of the shielding gas to different positions of the second plasma channel 61, an air distribution cavity 7 is formed between the air inlet component 4 and the middle component 3, and the side wall of the air inlet component 4 has an air inlet channel 41 connected to the air distribution cavity 7. The shielding gas can enter the air distribution cavity 7 through the air inlet channel 41, and the shielding gas is distributed to the second plasma channel 61 through the air distribution cavity 7.

[0088] Specifically, Figure 8 As shown, the air inlet 4 is provided with a first protective gas channel 42, and the two ends of the first protective gas channel 42 are respectively connected to the gas distribution cavity 7 and the end of the expansion section 611 away from the sudden expansion straight section 612. Figure 7 As described above, the protective gas in the gas distribution cavity 7 can enter the gap between the gas inlet member 4 and the protrusion 33 through the first protective gas channel 42 , and then enter the expansion section 611 through the second air hole in the middle of the insulating member 5 .

[0089] In some embodiments, Figure 8 As shown, the first shielding gas channel 42 is arranged at an angle, and the axis of the first shielding gas channel 42 is not in the same plane as the axis of the expansion section 611, so that the shielding gas has a tendency to move circumferentially along the expansion section 611 after entering the expansion section 611, thereby forming a spiral airflow in the expansion section 611 and constraining the plasma jet of the expansion section 611.

[0090] In some embodiments, in order to be able to confine the plasma jet of the suddenly expanded straight tube section 612, as Figure 8 As shown, the air inlet member 4 is further provided with an air inlet hole 43 connected to the air distribution cavity 7, and the air inlet hole 43 and the first protective gas channel 42 can be alternately distributed around the axis of the air inlet member 4, as shown in FIG. Figure 9 As shown, the insulating member 5 is provided with a vent hole 51. Figure 5 and Figure 6 As shown, the anode 6 is provided with an exhaust hole 62 , and the exhaust hole 62 extends from the top surface of the anode 6 to the protruding shoulder 614 .

[0091] The protective gas in the gas distribution cavity 7 can enter the ventilation hole 51 from the air inlet hole 43, and then enter the sudden-expansion straight cylinder section 612 through the exhaust hole 62. That is, the air inlet hole 43, the ventilation hole 51, and the exhaust hole 62 are connected in sequence to form a second protective gas channel. Since the protective gas enters the sudden-expansion straight cylinder section 612 from the sudden-expansion shoulder 614, it is more convenient for the protective gas to form a protective gas layer in the area near the electrode in the sudden-expansion straight cylinder section 612. The second protective gas channel and the first protective gas channel 42 cooperate to introduce the protective gas, which can effectively increase the attachment area of the arc root and reduce the heat flux density flowing to the anode 6, thereby suppressing the ablation of the anode 6 and prolonging the service life of the arc plasma generator.

[0092] The exhaust hole 62 can be configured as one, or can be configured as two, three, four, etc.

[0093] In at least one embodiment, as Figure 5 shown, the exhaust hole 62 is configured as four, and the four exhaust holes 62 are evenly distributed around the axis of the anode 6.

[0094] In some embodiments, in order to enable the protective gas discharged from the exhaust hole 62 to naturally form a swirling gas in the sudden-expansion straight cylinder section 612, the exhaust hole 62 can extend linearly and be inclined. The axis of the exhaust hole 62 is skew to the axis of the sudden-expansion straight cylinder section 612, so that the protective gas has a tendency to move circumferentially along the sudden-expansion straight cylinder section 612 after entering the sudden-expansion straight cylinder section 612, thereby forming a spiral air flow in the sudden-expansion straight cylinder section 612.

[0095] The above exhaust hole 62 is convenient for processing and can effectively make the protective gas form a swirling gas film in the sudden-expansion straight cylinder section 612. On the basis of the above embodiments, the axis of the air inlet hole 43 in the air inlet member 4 can be parallel to the axis of the air inlet member 4, and the axis of the ventilation hole 51 in the insulating member 5 can be parallel to the axis of the insulating member 5, that is, the air inlet member 4 and the insulating member 5 introduce the protective gas into the exhaust hole 62 along the axis.

[0096] Of course, the exhaust hole 62 is not limited to the above structural form. The exhaust hole 62 can also be arc-shaped, spiral-shaped, etc., so that the protective gas has a tendency to move circumferentially along the sudden-expansion straight cylinder section 612 through the guiding action of the exhaust hole 62.

[0097] In addition, the material of the insulating member 5 can be selected from polytetrafluoroethylene, ceramics, etc.

[0098] The cooling structure of the arc plasma generator will be specifically described below:

[0099] The cooling working medium can directly enter the first cooling channel 32 of the intermediate member 3 and the second cooling channel 63 of the anode 6 through an external pipeline to cool the two.

[0100] In order to achieve better cooling effect, in some embodiments, as Figure 3As shown, the above-mentioned arc plasma generator further includes a first cooling sleeve 8 and a second cooling sleeve 9; the first cooling sleeve 8 is sleeved outside the intermediate member 3 and forms a first cooling chamber between the first cooling sleeve 8 and the intermediate member 3; the second cooling sleeve 9 is sleeved outside the anode 6 and forms a second cooling chamber between the second cooling sleeve 9 and the anode 6; the air inlet member 4 is clamped between the first cooling sleeve 8 and the second cooling sleeve 9, as Figure 7 and Figure 8 shown, the air inlet member 4 is provided with a cooling working medium guiding through hole 44 that communicates the first cooling chamber with the second cooling chamber.

[0101] As Figure 3 shown, the first cooling sleeve 8 has a cooling working medium outlet 81, and the second cooling sleeve 9 has a cooling working medium inlet 91. The cooling working medium can flow into the second cooling chamber through the cooling working medium inlet 91, flow into the first cooling chamber through the cooling working medium guiding through hole 44, and finally flow out from the cooling working medium outlet 81.

[0102] The cooling working medium guiding through holes 44 can be configured in multiple numbers, and the multiple cooling working medium guiding through holes 44 are uniformly arranged around the axis of the air inlet member 4.

[0103] Specifically, the first cooling channel 32 in the intermediate member 3 communicates with the first cooling chamber, and the second cooling channel 63 in the anode 6 communicates with the second cooling chamber, so that the cooling working medium can enter the interiors of the intermediate member 3 and the anode 6 for cooling, achieving a better heat dissipation effect.

[0104] It should be additionally noted that in order to ensure good sealing performance of the above-mentioned arc plasma generator, sealing rings are provided between two adjacent structures up and down. For example, the bottom end of the second cooling sleeve 9 abuts against the annular groove at the top end of the bottom insulating layer 22, and a sealing ring is clamped between the second cooling sleeve 9 and the annular groove to prevent the leakage of the cooling working medium.

[0105] The following combines Figure 3 to elaborate in detail on the working process of the arc plasma generator:

[0106] Before the above-mentioned arc plasma generator is started, a certain flow rate of protective gas (usually a gas with a relatively low enthalpy value that is easy to be broken down and ionized, preferably argon) can be sent through the air inlet member 4. Subsequently, the working medium gas enters the intake area 311 and the discharge area 312 from the two working medium gas inlets 111 on the cathode 1 to generate plasma. After the plasma jet passes through the air inlet member 4 and the insulating member 5 and enters the anode 6, it expands and accelerates through the expansion section 611 at the upper part of the anode 6. Under the action of aerodynamic force, the arc root adheres to the sudden expansion straight cylinder section 612, and finally flows out from the tail contraction beam section 613.

[0107] The flow rate of the shielding gas can be reasonably adjusted according to the operating power of the arc plasma generator. The shielding gas enters the gas distribution cavity 7 through the gas inlet channels 41 around the gas inlet member 4, and then one part rotates and flows to the expansion section 611 above the anode 6 after passing through the first shielding gas channel 42, and the other part flows out from the sudden expansion shoulder 614 of the anode 6 through the second shielding gas channel and flows to the sudden expansion straight cylinder section 612 below the anode 6, forming a gas film to confine the arc plasma and protect the anode.

[0108] To improve the heat dissipation efficiency of the generator, during the above process, the cooling working fluid flows into the second cooling cavity from the cooling working fluid inlet 91, flows into the first cooling cavity through the cooling working fluid guide holes 44, and finally flows out from the cooling working fluid outlet 81.

[0109] The wires of the cathode 1 and the anode 6 can be respectively connected to the outside of the cathode 1 and the bottom support member 23, and the auxiliary arc ignition circuit can be connected to the outside of the gas inlet member 4.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An arc plasma generator, characterized in that, It comprises a cathode (1), an insulating support assembly (2), an intermediate piece (3), an air intake piece (4), an insulating piece (5) and an anode (6); The cathode (1) is connected to the top end of the insulating support component (2); The intermediate member (3), the gas inlet member (4), the insulating member (5) and the anode (6) are clamped on the insulating support component (2) from top to bottom, the intermediate member (3) having a first plasma channel (31), the cathode (1) penetrating the top end of the insulating support component (2) and extending into the first plasma channel (31) and used for filling the first plasma channel (31) with working gas, the anode (6) having a second plasma channel (61), the second plasma channel (61) being connected to the first plasma channel (31) via the gas inlet member (4) and the insulating member (5), the gas inlet member (4) being used for distributing protective gas into the second plasma channel (61) and forming a spiral protective gas on the surface of the second plasma channel (61); The second plasma channel (61) comprises an expansion section (611), a sudden expansion straight tube section (612) and a contraction beam section (613) which are sequentially connected from top to bottom, the caliber of the sudden expansion straight tube section (612) being larger than the caliber of any part of the expansion section (611) and forming a sudden expansion shoulder (614) between the expansion section (611); An air distribution cavity (7) is formed between the air intake member (4) and the intermediate member (3); a side wall of the air intake member (4) has an air intake passage (41) connected to the air distribution cavity (7) for intake of the protective gas; the air intake member (4) is provided with a first protective gas passage (42); two ends of the first protective gas passage (42) are respectively connected to the air distribution cavity (7) and one end of the expansion section (611) away from the sudden expansion straight cylinder section (612); The first shielding gas channel (42) is arranged obliquely, and the axis of the first shielding gas channel (42) is not in the same plane as the axis of the expansion section (611); The air inlet member (4) is further provided with an air inlet hole (43) connected to the air distribution chamber (7), the insulating member (5) is provided with an air vent (51), the anode (6) is provided with an exhaust hole (62), the exhaust hole (62) extends from the top surface of the anode (6) to the expanded shoulder (614), and the air inlet hole (43), the air vent (51) and the exhaust hole (62) are connected in sequence to form a second protective gas channel.

2. The arc plasma generator according to claim 1, wherein The cathode (1) comprises an upper substrate (11), a cathode middle portion (12) and a lower tip (13); the upper substrate (11) is connected to the top of the insulating support assembly (2); the upper substrate (11) has at least one working gas inlet (111) connected to the first plasma channel (31); one end of the cathode middle portion (12) is fixedly connected to the upper substrate (11); and the other end is clamped with the lower tip (13); the lower tip (13) is located in the first plasma channel (31); A cooling cavity (121) is provided inside the middle part (12) of the cathode. The upper substrate (11) has a cooling medium inlet channel (112) and a cooling medium discharge channel (113) that communicate with the cooling cavity (121).

3. The arc plasma generator according to claim 1, characterized in that, The insulating support assembly (2) includes a top insulating layer (21), a bottom insulating layer (22), a bottom support (23), and a locking member (24). The top insulating layer (21) is connected to the bottom support (23) through the locking member (24) to clamp the intermediate member (3), the air inlet member (4), the insulating member (5), and the anode (6) between the top insulating layer (21) and the bottom support (23). The bottom insulating layer (22) is installed on one side of the bottom support (23) facing the top insulating layer (21).

4. The arc plasma generator according to claim 1, characterized in that, The first plasma channel (31) includes an air inlet area (311) and a discharge area (312). Both ends of the discharge area (312) communicate with the air inlet area (311) and the second plasma channel (61) respectively. The diameter of the end of the air inlet area (311) close to the discharge area (312) gradually decreases along the air inlet direction.

5. The arc plasma generator according to claim 1, wherein, The diameter of the expansion section (611) gradually increases along the direction approaching the sudden-expansion straight tube section (612), and the diameter of the contraction beam section (613) gradually decreases along the direction away from the sudden-expansion straight tube section (612).

6. The arc plasma generator according to claim 1, characterized in that, The exhaust hole (62) is inclined, and the axis of the exhaust hole (62) is skew to the axis of the sudden-expansion straight tube section (612), so that the protective gas discharged from the second protective gas channel forms a spiral air flow in the sudden-expansion straight tube section (612).

7. The arc plasma generator according to claim 1, wherein It further includes a first cooling sleeve (8) and a second cooling sleeve (9); The first cooling sleeve (8) is sleeved outside the intermediate member (3) and forms a first cooling cavity between it and the intermediate member (3); The second cooling sleeve (9) is sleeved outside the anode (6) and forms a second cooling cavity between it and the anode (6); The air inlet member (4) is clamped between the first cooling sleeve (8) and the second cooling sleeve (9), and a cooling medium guide through hole (44) communicating the first cooling cavity and the second cooling cavity is provided on the air inlet member (4).

8. The arc plasma generator according to claim 7, characterized in that, A first cooling channel (32) with both ends communicating with the first cooling cavity is provided inside the intermediate member (3). One end of the first cooling channel (32) is higher than the other end and the diameter of one end is larger than that of the other end; A second cooling channel (63) with both ends communicating with the second cooling cavity is provided inside the anode (6). One end of the second cooling channel (63) is higher than the other end and the diameter of one end is larger than that of the other end.

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