Plasma ignition device and method applied to explosion spraying field

Abstract

The invention provides a plasma ignition device applied to the field of explosion spraying, which comprises a gas supply system for supplying premixed gas into a combustion chamber; the stepping plasma ignition system comprises a control end, a stepping motor, a cathode and an anode, the cathode and the anode are coaxially arranged in the combustion chamber, and the control end is electrically connected with the stepping motor and the cathode. The control module is used for controlling the stepping motor to drive the cathode to move in the axial direction so as to adjust the discharge gap between the cathode and the anode and controlling the discharge voltage of the cathode; and the cooling system covers the outer side of the combustion chamber and is used for cooling the combustion chamber. High ignition frequency can be achieved, and the ignition delay time and the initial shape and size of the flame nucleus are controlled by setting the energy of the plasma generation device and the discharge voltage, the discharge frequency and the discharge pulse width of the power supply.

Description

Technical Field

[0001] This invention relates to the field of thermal spraying technology, and more specifically to a plasma ignition device and method for use in the field of explosive spraying. Background Technology

[0002] In high-end equipment manufacturing and maintenance fields such as aero-engine blade coating repair, heavy-duty gas turbine component surface strengthening, and petrochemical pipeline corrosion and wear-resistant treatment, explosive spraying technology has become one of the core technologies for surface modification of key components due to its high coating bonding strength, high density, and excellent wear and corrosion resistance. This technology involves mixing fuel gas and combustion-supporting gas in a specific ratio and introducing the mixture into a combustion chamber. The mixture is ignited by an ignition device to form a periodic deflagration wave. The high-temperature, high-pressure gas flow generated by the deflagration drives the sprayed powder to impact the substrate surface at high speed, ultimately forming a high-performance coating. The coating quality directly determines the service life and operational safety of the equipment. Therefore, stable ignition during the deflagration process, precise control of ignition energy, and the compatibility between the ignition system and the spraying combustion chamber are the core factors affecting the efficiency, coating consistency, and process stability of explosive spraying.

[0003] Currently, the ignition technology used in the field of explosive spraying is mainly high-voltage electric spark ignition. For example, the patent "A Flexible Explosive Spraying Device" adopts this scheme, which uses a high-voltage electrode to generate an electric spark in the mixed gas area of ​​the combustion chamber to ignite the gas. However, this technology has obvious limitations: on the one hand, the electric spark energy is greatly affected by the electrode gap, gas pressure and humidity. In a high-concentration fuel gas mixture environment, insufficient ignition energy or excessive breakdown is prone to occur, resulting in an unstable detonation process and uneven coating thickness. On the other hand, the electrodes are prone to ablation and deformation in a high-temperature deflagration environment for a long time, requiring regular replacement. This not only increases equipment maintenance costs but also reduces production efficiency due to downtime maintenance. To address the aforementioned issues, semiconductor laser ignition technology has emerged, such as the solution proposed in the patent "A Laser Ignition Device and a Combustion Chamber Thereof." However, existing technologies have not yet solved the problem of laser energy attenuation: when the laser beam passes through the transparent observation window of the combustion chamber, it is easily affected by the contamination of powder particles adhering to the window surface, leading to increased energy loss and making it impossible to stably ignite high-pressure mixed gases. In addition, it is difficult to set up optical windows in hypersonic spray guns, and laser ignition systems are expensive. Currently, they are only used on a small scale in high-end fields such as aerospace, making it difficult to achieve industrialization and promotion.

[0004] Plasma ignition technology, as an emerging ignition method in recent years, uses a plasma generator to produce a high-temperature plasma jet to ignite a gas mixture, significantly shortening the deflagration-to-detonation (DDT) distance and enabling rapid initiation of gas within a tube. It also features high ignition energy and a wide range of adaptable gas concentrations. However, current limitations of this technology lie in the complexity of plasma generator structures involving cooling mechanisms, as illustrated in the patent "A Heat Dissipation Device and Plasma Equipment." Furthermore, in the field of explosive spraying, there is currently no suitable plasma ignition structure design and application method for explosive spraying equipment. Summary of the Invention

[0005] In view of this, the present invention provides a plasma ignition device and method for use in the field of explosive spraying, in order to solve the problems of existing major explosive spraying ignition technologies, such as reliance on high-pressure spark plugs, large ignition delay, low energy utilization, and severe coating oxidation / decarburization.

[0006] This invention provides the following technical solution: a plasma ignition device for use in the field of explosive spraying, comprising a gas supply system for supplying premixed gas into a combustion chamber; a stepping plasma ignition system comprising a control terminal, a stepping motor, a cathode, and an anode, wherein the cathode and anode are coaxially disposed in the combustion chamber, and the control terminal is electrically connected to the stepping motor and the cathode respectively, for controlling the stepping motor to drive the cathode to move axially to adjust the discharge gap between the cathode and the anode, and controlling the discharge voltage of the cathode; and a cooling system covering the outside of the combustion chamber for cooling the combustion chamber.

[0007] This invention also provides a plasma ignition method for use in the field of explosive spraying, comprising the following steps:

[0008] Step S1: Set the ignition parameters via the control terminal; Step S2: The control terminal calculates and outputs a pulse signal to the stepper motor according to the set ignition parameters, drives the stepper motor to move the cathode along the axial direction, and adjusts the discharge gap to the target position that matches the current gas type and pressure. Step S3: Open the solenoid valve to supply premixed gas into the combustion chamber; Step S4: The control terminal controls the high-voltage power supply to apply voltage to the cathode according to the set ignition parameters, generating a plasma arc at the adjusted discharge gap, igniting the premixed gas in the combustion chamber, forming an annular plasma flow, and initiating deflagration to detonation. Step S5: The detonation wave is ejected along the nozzle, completing one coat of paint. Step S6: Repeat steps S2 to S5 until the set number of ignition cycles is completed.

[0009] Compared with the prior art, the beneficial effects that the at least one technical solution adopted by the present invention can achieve include at least the following: (1) Achieve high ignition frequency (millisecond-level precise ignition) by setting the discharge voltage, discharge frequency and discharge pulse width of the plasma generator energy and power supply to control the ignition delay time and the initial shape and size of the flame core.

[0010] (2) The annular plasma ignition method was applied to the ignition device of explosive spraying for the first time. By adjusting the anode and cathode structure of the plasma ignition device, the range of adaptability of the ignition device to gases with different ionization difficulties was broadened, ensuring stable detonation in the early stage of deflagration.

[0011] (3) The plasma cooling device is directly attached to the inner wall of the sleeve of the deflagration device. The existing plasma generators need to add a water-cooled wall and an insulation layer to the outside of the cathode sleeve. The nozzle used in the explosive spraying technology has a water-cooled wall between itself and the outer sleeve. Applying the plasma ignition method to the existing spraying technology can just achieve the coupling of the two structures and functions. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of a plasma ignition device; Figure 2 This is a schematic diagram of the air supply device; Figure 3 This is a schematic diagram of a stepping plasma ignition system; Figure 4 This is a schematic diagram of the stepping process; Figure 5 This is a schematic diagram of the cooling device; Figure 6 It is a workflow diagram; Figure 7 This is a flowchart of the control endpoint fire parameter calculation and adaptive adjustment logic; Figure reference numerals: 1. Gas delivery system; 11. Gas cylinder; 12. Premixed gas; 13. Solenoid valve; 14. Intake pipe; 15. Combustion chamber; 16. Pressure reducing valve; 17. Flow meter; 2. Stepping plasma ignition system; 21. Control terminal; 22. Stepper motor; 23. Cathode; 231. Cathode end consumables; 24. Anode; 3. Cooling system; 31. Insulation layer; 32. Inlet section; 33. Outlet section; 34. Thermometer; 35. Inner wall of anode sleeve; 36. Flow sensor. Detailed Implementation

[0014] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] like Figure 1 As shown, the present invention provides a plasma ignition device for use in the field of explosive spraying. The device consists of a gas supply system 1, a stepping plasma ignition system 2, and a cooling system 3 arranged sequentially along the same axis. The device centers on a through-type ignition gun tube and coaxially encloses a combustion chamber 15 within it. Insulating flanges are used at the front and rear ends to achieve airtight sealing and electrical isolation, ensuring the safe isolation of the high-voltage ignition system from the external environment.

[0017] like Figure 1 and Figure 2 As shown, the gas supply system 1 is used to supply premixed gas 12 to the combustion chamber 15. Specifically, the gas supply system 1 includes a gas cylinder 11, a pressure reducing valve 16, a solenoid valve 13, a flow meter 17, and symmetrically arranged intake pipes 14. The gas cylinder 11 stores fuel gas (such as acetylene, propane, hydrogen, etc.) and combustion-supporting gas (such as oxygen, air), which are mixed through the pipes to form premixed gas 12. The premixed gas 12 first passes through the pressure reducing valve 16 to reduce the pressure to the working pressure (usually 0.1-0.5 MPa), and then the solenoid valve 13 controls the opening and closing of the gas path. The flow meter 17 monitors and feeds back the flow signal in real time to achieve closed-loop precise control of the flow rate. Subsequently, the premixed gas 12 is simultaneously introduced into the combustion chamber 15 through symmetrically arranged intake pipes 14 of equal length. This symmetrical intake method can ensure symmetrical intake momentum and uniform flow field, avoiding ignition failure or unstable detonation caused by uneven airflow. Combustion chamber 15 itself is a pressure-resistant, sealed cavity with a convergent-divergent nozzle at the front end, which is used to accelerate the detonation products to high speed and eject them to achieve the spraying of the substrate material.

[0018] like Figure 1 , Figure 3 and Figure 4As shown, the stepping plasma ignition system 2 is used to rapidly ignite and detonate the premixed gas 12 in the combustion chamber 15. The system includes a control terminal 21, a stepper motor 22, a cathode 23, and an anode 24. The cathode 23 and anode 24 are coaxially arranged within the combustion chamber 15. The anode 24 is a conductive cylinder with its inner cavity smoothly transitioning into the combustion chamber 15 and reliably grounded to ensure high-voltage safety. The cathode 23 has a central rod-shaped structure and can move axially within the anode 24 cavity. The control terminal 21 is electrically connected to both the stepper motor 22 and the cathode 23, controlling the stepper motor 22 to drive the cathode 23 to move axially, thereby adjusting the discharge gap between the cathode 23 and the anode 24 and controlling the discharge voltage of the cathode 23.

[0019] like Figure 4 As shown, a detachable cathode end consumable 231 is provided at the end of the cathode 23. This cathode end consumable 231 has a frustum-shaped structure, with its outer diameter gradually increasing axially towards the anode 24. When the cathode 23 is driven by the stepper motor 22 to penetrate deeper into the anode 24, an annular discharge gap (e.g., ...) is formed between the outer conical surface of the cathode end consumable 231 and the inner wall of the anode 24. Figure 4 (The d2 and d3 markings indicate different gaps). This frustum-shaped structure design results in a ring-shaped distribution of discharge gaps, which, compared to traditional point or line discharges, generates a more uniform ring-shaped plasma flow, thereby achieving uniform ionization of the premixed gas and ensuring stable initiation in the early stages of deflagration. Simultaneously, the cathode end consumable 231 features a detachable design, facilitating replacement after long-term use and reducing maintenance costs due to erosion.

[0020] Stepper motor 22 converts rotational motion into linear displacement of cathode 23 via a lead screw or threaded joint. Control terminal 21 sends pulse signals to drive stepper motor 22, precisely controlling the feed or retraction of cathode 23, thereby adjusting the size of the annular discharge gap between the anode and cathode as needed. This adjustment mechanism allows the device to find the optimal detonation gap for premixed gases with different ionization difficulties (such as easily ionized acetylene and difficult-to-ionize propane), ensuring stable arc ignition and uniform ionization under different voltage conditions.

[0021] like Figure 1 and Figure 5As shown, the cooling system 3 surrounds the combustion chamber 15 and is used to cool the combustion chamber 15. Specifically, the cooling system 3 includes an insulating layer 31 surrounding the combustion chamber 15 and an annular water jacket formed outside the insulating layer 31. The annular water jacket has a spiral zigzag flow channel inside to increase the flow path and heat exchange time of the cooling water. The cooling water enters from the lower inlet section 32, exchanges heat around the gun tube, and exits from the upper outlet section 33. Fixed thermometers 34 are respectively installed at the inlet section 32 and the outlet section 33 to monitor the inlet and outlet temperatures of the cooling water. A flow sensor 36 is also installed on the pipeline of the annular water jacket to detect the cooling water flow rate. The signals from the thermometers 34 and the flow sensor 36 are both transmitted back to the control terminal 21 to realize automatic shutdown protection in case of over-temperature and under-flow. Low conductivity water is preferably used for cooling to prevent electrolytic corrosion of the inner wall 35 of the anode sleeve. One of the innovations of this invention is that it makes full use of the existing water-cooling structure of the explosive spraying device itself. The nozzle used in explosive spraying technology has a water-cooling wall between itself and the outer sleeve. The plasma ignition device is integrated into it without the need for additional complex water-cooling structures, thus achieving a clever coupling of function and structure.

[0022] The following is combined with Figures 6 to 7 This invention describes its usage and workflow.

[0023] In use, the ignition parameters are first set on the interface of the control terminal 21, including the gas type, filling pressure, gas supply flow rate, discharge pulse width, and number of ignition cycles. The control terminal 21 automatically calculates the target feed amount (i.e., the optimal discharge gap) of the stepper motor 22 and the set voltage of the high-voltage power supply based on the built-in adaptive ignition parameter calculation module.

[0024] Specifically, the storage unit of the control terminal 21 contains a pre-set "gas-breakdown characteristic database". After the operator inputs the gas type and preset filling pressure, the system performs parameter conversion based on the modified Paschen's Law model. For engineering simplification, a simplified control function can also be used to determine the relationship between the set voltage, gas pressure, and gap. The control terminal 21 calculates the maximum allowable discharge gap within the maximum allowable voltage range of the high-voltage power supply and converts it into the number of feed pulses for the stepper motor 22. Then, it drives the stepper motor 22 to rotate the corresponding number of steps, precisely adjusting the position of the cathode 23 to the target discharge gap.

[0025] After the gap is adjusted, the control terminal 21 opens the solenoid valve 13, supplying premixed gas 12 into the combustion chamber 15. After a short delay (typically milliseconds) to ensure the combustion chamber is full and the flow field is stable, the control terminal 21 triggers the high-voltage power supply, applying a set voltage to the cathode 23. Under the high voltage, breakdown occurs at the annular discharge gap between the cathode 23 and the anode 24, generating an annular plasma arc, which instantly ignites the premixed gas 12 in the combustion chamber 15, forming an annular plasma flow. This plasma flow has a high energy density, which can significantly shorten the distance and time from deflagration to detonation, enabling the mixed gas to detonate rapidly and form a stable detonation wave. The detonation wave is ejected at high speed along the nozzle, driving the sprayed powder to impact the substrate surface, completing one spraying operation.

[0026] After one spraying cycle, the stepper motor 22 can retract a certain distance to disconnect the discharge circuit, the high-voltage power supply is turned off, and the system repeats the above process at set intervals until the entire ignition cycle is completed. When stopping, the solenoid valve 13 and the high-voltage power supply are turned off first, the stepper motor 22 returns to zero, and the cooling system 3 continues to run for a period of time until the gun barrel cools down before stopping.

[0027] In routine maintenance, it is only necessary to periodically check the erosion of the cathode end consumable 231, replace it when necessary, and clean the carbon deposits or dust that may accumulate in the inner cavity of the anode 24 to maintain stable detonation and spraying performance for a long time.

[0028] The specific workflow is as follows: The control terminal 21 is not only used to send control signals, but also has a built-in adaptive ignition parameter calculation module. The core function of this module is to automatically calculate the optimal cathode-cathode gap value (d) and high-voltage power supply voltage (V) based on the user-input operating parameters, ensuring that the ignition energy (E) is always maintained within the effective detonation range (MIE). <E<E saturation Within. MIE is the minimum ignition energy of acetylene, E saturation This represents the electrode ablation threshold.

[0029] The specific setup method and calculation logic are as follows: 1. Mapping relationship between input variables and control variables The storage unit of control terminal 21 contains a pre-set "gas-breakdown characteristic database". When the operator inputs the gas type (such as acetylene, propane, hydrogen) and the preset filling pressure (P), the system will determine the control parameters according to the following logic: Input variables (independent variables): α: Dielectric strength coefficient of the gas (depends on the type of gas; for example, acetylene is easily ionized, so α is low; propane is difficult to ionize, so α is high).

[0030] P: Premixed gas pressure in the combustion chamber (determined by flow meter 17 and pressure reducing valve 16).

[0031] Q: The gas supply flow rate affects the degree of gas turbulence, which in turn affects the heat dissipation of the flame core.

[0032] Output variables (dependent variables): L: The feed amount of stepper motor 22 (corresponding to the linear gap d between cathode 23 and anode 24).

[0033] V set : The set voltage of the high-voltage power supply.

[0034] T pulse : Discharge pulse width (determines the duration of energy).

[0035] 2. Parameter Calculation Model (Core Algorithm) Control terminal 21 performs parameter conversion based on the modified Paschen's Law model. Since this device operates under high-pressure spraying conditions, the breakdown voltage V... b The pressure P and the gap d satisfy an approximate relationship:

[0036] Where A and B are constants related to the type of gas, and γ is the secondary electron emission coefficient of the cathode material, which is related to the cathode material.

[0037] For engineering simplification, the control terminal adopts the following simplified control function:

[0038] Where k1 is the dielectric constant related to the type of gas, and V0 is the system base voltage offset.

[0039] Example of parameter adjustment steps Step S1 (Operating Condition Setting): The user sets the gas used for this spraying to be "acetylene", and the mixed gas pressure P=0.2MPa.

[0040] Step S2 (Gap Calculation): The system, after consulting a table, determined that the optimal ignition breakdown field strength for acetylene is relatively low. To obtain a larger plasma ignition nucleus volume (to shorten the DDT distance), the system tends to choose a larger gap d. However, under high pressure, an excessively large d would lead to an excessively high breakdown voltage exceeding the power supply load. Therefore, the system calculations satisfy V set ≤V max The maximum allowable gap d for (maximum power supply voltage) opt .

[0041] Example calculation logic: If the power supply limit is 20kV and the breakdown field strength of acetylene at the current atmospheric pressure is 5kV / mm, then the maximum gap d opt ≈4mm.

[0042] Step S3 (Execute Action): The control terminal will calculate d opt Convert this to the number of pulses for a stepper motor 22. Given that the stepper motor leadscrew lead is h and the step angle is θ, calculate the number of feed pulses. The control unit drives the stepper motor to rotate N steps, precisely adjusting the position of cathode 23.

[0043] Step S4 (Energy Matching): After determining the gap d, the system matches the energy according to the energy formula. or Set pulse width T pulse Ensure that the total energy E is greater than the minimum ignition energy (MIE) of acetylene and less than the electrode ablation threshold (E). saturation ).

[0044] In the above embodiment, the axial movement of the cathode 23 is driven by the stepper motor 22. As another variant embodiment of the invention, the driving mechanism of the cathode 23 can also be a hydraulic cylinder or a pneumatic cylinder. The control end 21 precisely controls the extension length of the piston rod by controlling the opening and direction of the hydraulic or pneumatic valve, thereby driving the cathode 23 to the target position. This driving method is suitable for applications requiring high thrust or with special requirements for electrical explosion protection.

[0045] In the above embodiment, the cathode end consumable 231 has a frustum-shaped structure. In other embodiments of the present invention, the cathode end consumable 231 may also adopt other shapes, for example: (1) Spherical: The end of the cathode is hemispherical or spherical, forming an annular gap with the inner wall of the anode; (2) Frustum shape: The cathode end is a multi-faceted frustum shape, which can produce a multi-point ignition effect; (3) Cylindrical with spiral groove: The cylindrical surface at the end of the cathode is provided with a spiral groove, which can guide the airflow to rotate and enhance the mixing of plasma and gas.

[0046] Regardless of the shape used, the core principle is to create a ring-shaped or near-ring-shaped discharge region between the cathode end and the inner wall of the anode, in order to generate a uniform ring-shaped plasma flow.

[0047] In the above embodiments, the cooling system 3 adopts a spiral flow channel structure with a single inlet and a single outlet. In other embodiments of the present invention, the cooling system 3 may also take the following form: (1) Dual-channel water inlet and outlet structure: Two water inlets and two water outlets are set on both sides of the gun barrel to form symmetrical cooling and improve cooling uniformity; (2) Axial straight-through flow channel structure: Multiple straight-through water channels parallel to the gun barrel axis are set on the outside of the insulation layer 31, and the two ends are connected by an annular water collection cavity to form axial flow cooling; (3) Use other cooling media: For special high-temperature occasions, cooling oil or air can be used as cooling media. In this case, the flow channel structure and heat exchange area need to be adjusted accordingly.

[0048] In the above embodiment, the control terminal 21 automatically calculates the optimal ignition parameters using a built-in adaptive ignition parameter calculation module. As another variation of the present invention, the control terminal 21 may also employ the following control strategy: (1) Manual mode: The operator manually inputs the discharge gap value and discharge voltage value based on experience. The control terminal 21 only performs the driving action and does not perform automatic calculation. (2) Semi-automatic mode: The control terminal 21 provides a recommended parameter range, and the operator selects the set value within the range. The control terminal 21 executes according to the set value. (3) Learning mode: The control terminal 21 records the parameter combination of each successful or failed ignition, establishes a historical database, and optimizes the parameter model through machine learning algorithm to achieve self-learning and self-optimization control.

[0049] The plasma ignition device and method of the present invention are applicable not only to Figure 1 The straight-tube detonation spraying device shown can also be applied to other types of detonation spraying devices, such as: (1) Bending barrel explosion spraying device: The coaxial plasma ignition system of the present invention can also be integrated into its combustion chamber, and the problem of difficult ignition of the bending section can be solved by utilizing the advantages of annular plasma ignition. (2) Multi-tube parallel explosive spraying device: For occasions that require large-area spraying or simultaneous spraying of multiple points, the plasma ignition system of the present invention can be set in multiple parallel combustion chambers and synchronously controlled by the same control terminal 21. (3) Long-barrel explosion spraying device: For devices with long barrels, the plasma ignition system of the present invention can be installed at the rear of the combustion chamber to ensure that the detonation wave propagates stably in the long barrel by utilizing its characteristic of shortening the DDT distance.

[0050] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of protection of the present invention, should still fall within the scope of the present invention. Furthermore, the technical features, technical features and technical solutions, and technical solutions in the present invention can be freely combined and used.

Claims

1. A plasma ignition device for use in the field of explosive spraying, characterized in that, include: An air supply system (1) is used to supply premixed gas (12) into the combustion chamber (15). The stepping plasma ignition system (2) includes a control terminal (21), a stepper motor (22), a cathode (23) and an anode (24). The cathode (23) and the anode (24) are coaxially arranged in the combustion chamber (15). The control terminal (21) is electrically connected to the stepper motor (22) and the cathode (23) respectively, and is used to control the stepper motor (22) to drive the cathode (23) to move axially to adjust the discharge gap between the cathode (23) and the anode (24), and to control the discharge voltage of the cathode (23). A cooling system (3) is provided, covering the outside of the combustion chamber (15), for cooling the combustion chamber (15).

2. The plasma ignition device for use in explosive spraying as described in claim 1, characterized in that, The cathode (23) is provided with a detachable cathode end consumable (231) at its end. The cathode end consumable (231) is a frustum-shaped structure, and its outer diameter gradually increases along the axial direction towards the anode (24) to form an annular discharge gap with the inner wall of the anode (24).

3. The plasma ignition device for use in explosive spraying as described in claim 2, characterized in that, The gas delivery system (1) includes a gas cylinder (11), a pressure reducing valve (16), a solenoid valve (13), a flow meter (17), and symmetrically arranged air intake pipes (14); the premixed gas (12) is delivered from the gas cylinder (11) through the pressure reducing valve (16), the solenoid valve (13), and the flow meter (17) in sequence, and then simultaneously enters the combustion chamber (15) through the symmetrically arranged air intake pipes (14).

4. The plasma ignition device for use in explosive spraying as described in claim 3, characterized in that, The cooling system (3) includes an insulating layer (31) covering the outside of the combustion chamber (15) and an annular water jacket formed on the outside of the insulating layer (31). The annular water jacket has an inlet section (32) and an outlet section (33). A thermometer (34) is provided at the inlet section (32) and the outlet section (33), respectively. A flow sensor (36) is provided on the pipeline of the annular water jacket.

5. The plasma ignition device for use in explosive spraying as described in claim 4, characterized in that, The control terminal (21) has an adaptive ignition parameter calculation module built in. The adaptive ignition parameter calculation module is used to calculate the feed amount of the stepper motor (22), the set voltage of the high-voltage power supply and the discharge pulse width according to the input gas type, preset filling pressure and gas supply flow rate.

6. A plasma ignition method for use in the field of explosive spraying, employing the plasma ignition device for use in the field of explosive spraying as described in claim 5, characterized in that, Includes the following steps: Step S1: Set the ignition parameters through the control terminal (21); Step S2: The control terminal (21) calculates and outputs a pulse signal to the stepper motor (22) according to the set ignition parameters, drives the stepper motor (22) to drive the cathode (23) to move along the axial direction, and adjusts the discharge gap to the target position that matches the current gas type and pressure. Step S3: Open the solenoid valve (13) to supply premixed gas (12) into the combustion chamber (15); Step S4: The control terminal (21) controls the high-voltage power supply to apply voltage to the cathode (23) according to the set ignition parameters, and generates a plasma arc at the adjusted discharge gap, igniting the premixed gas (12) in the combustion chamber (15), forming an annular plasma flow, and triggering deflagration to detonation. Step S5: The detonation wave is ejected along the nozzle, completing one coat of paint. Step S6: Repeat steps S2 to S5 until the set number of ignition cycles is completed.

7. The plasma ignition method for use in explosive spraying as described in claim 6, characterized in that, In step S2, the method for determining the target position is as follows: based on the preset gas type and filling pressure, determine the optimal discharge gap that can achieve stable arc ignition within the maximum allowable voltage range of the high-voltage power supply, and control the stepper motor (22) to drive the cathode (23) to move to the position corresponding to the optimal discharge gap.

8. The plasma ignition method for use in explosive spraying as described in claim 7, characterized in that, In step S4, the control terminal (21) adjusts the discharge pulse width according to the set ignition parameters to ensure that the total ignition energy is greater than the minimum ignition energy of the premixed gas and less than the electrode ablation threshold.

9. The plasma ignition method for use in explosive spraying as described in claim 8, characterized in that, In step S4, the plasma arc forms an annular discharge gap between the frustum-shaped cathode end consumable (231) at the end of the cathode (23) and the inner wall of the anode (24), generating a uniform annular plasma flow.

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