Repetitive Plasma Jet Ignition System and Method Using Energetic Modified Working Medium

Abstract

A high-repetition-rate plasma jet ignition system and method using an energetic modified working fluid. The system includes six parts: a capillary jet device, a pulsed voltage generation circuit, a pulsed current generation circuit, a thyristor trigger circuit, an LC series resonance charging circuit, and a control system. The capillary jet device uses a polymer modified working fluid doped with active metal powder. While generating plasma by arc ablation of the working fluid material, the chemical reaction energy release of the working fluid components improves the temperature and heat flux of the plasma jet. Through the pulsed voltage-pulsed current generation circuit, the jet device can be driven to operate repeatedly based on the plasma jet injection trigger principle. The LC series resonance charging circuit is used to quickly charge the energy storage capacitor, enabling the system to repeatedly generate hot plasma jets at a maximum frequency of 20 Hz. The system improves the ignition efficiency of the ignition system by two means: releasing the chemical energy of the energy-enhanced modified working fluid to increase the energy of a single-shot plasma jet and the heat accumulation effect of the repetitive frequency jet.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace propulsion system ignition, and particularly relates to a repetitive plasma jet ignition system and method using an energetic modified working medium. Background Art

[0002] With the progress of aerospace technology, aircraft engines face difficulties in reigniting under extreme conditions such as high altitude, high speed, low pressure, and low temperature. The success rate of traditional spark ignition is low. In addition, the molecular structures of new propellants are different from those of traditional propellants, requiring higher ignition temperatures and energies. Facing the future development trend of aerospace propulsion systems, plasma ignition technology is one of the research hotspots. Compared with traditional ignition methods, plasma ignition has characteristics such as a large ignition area, short ignition delay time, and high ignition energy utilization rate. According to different discharge forms, it can be divided into direct breakdown arc ignition, sliding arc discharge, nanosecond pulsed corona discharge ignition, plasma jet ignition, etc.

[0003] However, the above plasma ignition devices still have certain application limitations: the structure of nanosecond pulsed discharge plasma power supplies is generally complex; the ions and neutral gas temperatures of non-equilibrium low-temperature plasmas are relatively low, and the heat flux is small, resulting in limited ignition ability for solid working media; sliding arc discharge and plasma torch jet ignition require the introduction of gas flow, including complex structures such as gas path valves, increasing the complexity of the ignition system and having the possibility of failure under some conditions.

[0004] Among them, capillary discharge is a form of discharge in which an arc ablates a low melting point and high boiling point polymer material to form a high-temperature and high-pressure plasma jet ejected from a capillary with an open end at one side. The plasma jet has characteristics such as high temperature (>10000K), high speed (1 - 10 km / s), high heat flux density (up to GW / m 2 level), and high exit pressure (>MPa), and can be applied to fields such as space electric propulsion, material spraying, harmful substance treatment, and propellant ignition. Capillary discharge only relies on solid working media to generate plasma jets, without the need for complex structures such as gas paths, valves, and gas cylinders, reducing the possibility of system failure and being suitable for the aerospace field with strict requirements for system reliability.

[0005] Traditional capillary discharge mostly relies on the electro-explosion of metal wires to conduct the capillary channel. After each discharge, the metal initiating wire needs to be replaced and cannot be operated repeatedly. In addition, restricted by the mass of the energy storage system and the strength of the capillary polymer working medium block, blindly increasing the single capillary discharge energy will, on the one hand, cause the mass and volume of the energy storage system to increase sharply, and on the other hand, increase the temperature and pressure inside the capillary in the polymer working medium, easily causing the capillary working medium block to break. Therefore, it is crucial to improve the single jet energy and the ignition efficiency of capillary discharge without changing the energy storage. Summary of the Invention

[0006] Aiming at the problems existing in the high-repetition-rate capillary discharge jet system in the prior art, the purpose of the present invention is to provide a high-repetition-rate plasma jet ignition system using an energetic-doped modified working medium, which comprises a two-gap capillary discharge jet device 19 using an energetic-doped capillary working medium, a pulse voltage generation circuit 9, a pulse current generation circuit 10, a thyristor trigger circuit 16, an LC series resonance charging circuit 17, and a control system 18. The capillary jet device 19 is driven by the pulse voltage generation circuit 9 and the pulse current generation circuit 10, and can operate repeatedly based on the plasma jet triggering principle. The pulse current generation circuit 10 generates pulsed discharge in the capillary gap 12 to ablate the energetic working medium 1 by arc, and the reaction between the active metal component and the polytetrafluoroethylene component releases chemical energy to further increase the temperature and heat flux of the plasma jet. In each discharge cycle, the control system 18 controls the LC series resonance charging circuit 17 to quickly charge the energy storage capacitor C1 in the pulse current generation circuit 10, controls the thyristor trigger circuit 16 according to the discharge frequency, and triggers the thyristors in the pulse current generation circuit 10 and the pulse voltage generation circuit 9 to cause capillary discharge. The system can generate capillary discharge plasma jets at a maximum frequency of 20 Hz. The system improves the ignition efficiency of the ignition system by two means: releasing the chemical energy of the energy-enhanced modified working medium to increase the energy of a single plasma jet, and the heat accumulation effect of the repetitive-frequency jet.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] A high-repetition-rate plasma jet ignition system using an energetic-modified working medium, comprising a capillary jet device 19, a pulse voltage generation circuit 9, a pulse current generation circuit 10, a thyristor trigger circuit 16, an LC series resonance charging circuit 17, and a control system 18; when applied to the ignition of a propulsion system, the capillary jet device 19 is connected to the engine 31.

[0009] The capillary jet device 19 uses an energy-enhanced modified working medium and can operate repeatedly. It includes an energy-doped working medium block 1, which is coaxially installed inside the housing 8. The energy-doped working medium block 1 is made of active metal powders ranging from nanoscale to micron-scale, mixed, pressed, sintered, and machined with polymer powders to form a modified energy-containing working medium, and a capillary channel 12 is machined at the axis, and a cylindrical channel 14 is machined on the side to communicate with the capillary channel 12; the front of the housing 8 is connected to the front flange cover plate 5, and the rear is connected to the rear flange cover plate 7; the front flange cover plate 5 is machined with an expanding cathode nozzle 6 coaxially; the anode 2 is inserted into the capillary channel 12 from the rear of the energy-doped working medium block 1, and the trigger electrode 3 is inserted into the cylindrical channel 14 on the side of the energy-doped working medium block 1, dividing the capillary channel 12 between the end of the anode 2 and the front flange cover plate 5 into two parts between the anode 2 and the trigger electrode 3, called the trigger channel 15, and two parts between the trigger electrode 3 and the front flange cover plate 5; insulators 4 are installed outside the anode 2 and the trigger electrode 3 to achieve electrical isolation from the housing, and the limit screw 11 is installed outside the insulator 4 and fixedly connected to the housing 8;

[0010] The connection relationships of each module in the high-repetition-rate plasma jet ignition system are as follows: the high-voltage output terminal of the pulse voltage generation circuit 9 is connected to the trigger electrode 3 of the capillary jet device 19, and the low-level output terminal is connected to the front flange cover plate 5 of the capillary jet device 19; the high-voltage output terminal of the pulse current generation circuit 10 is connected to the anode 2 of the capillary jet device 19, and the low-voltage output terminal is connected to the front flange cover plate 5 of the capillary jet device 19, and the front flange cover plate 5 of the capillary jet device 19 is grounded through a grounding wire; the high-voltage output terminal of the LC series resonance charging circuit 17 is connected to the high-voltage end of the energy storage capacitor C1 in the pulse current generation circuit 10, and the low-voltage output terminal is connected to the low-voltage end of the energy storage capacitor C1 in the pulse current generation circuit 10 to achieve rapid charging of the energy storage capacitor C1; the two drive voltage output terminals of the thyristor trigger circuit 16 are respectively connected to the thyristor SCR2 in the pulse voltage generation circuit 9 and the thyristor SCR1 in the pulse current generation circuit 10 to turn on the two thyristors; the control system 18 is connected to the LC series resonance charging circuit 17 and the thyristor trigger circuit 16 through optical fibers, and sends a charging start signal 23 to the LC series resonance charging circuit 17 and a trigger thyristor control turn-on signal 20 to the thyristor trigger circuit 16 according to the set frequency.

[0011] When applied to the ignition of a propulsion system, in the repetitive pulse plasma jet generation system, the capillary jet device 19 is connected to the end of the outer shell 27 of the engine 31. The propellant 28 is placed inside the engine combustion chamber 29. The propellant 28 can be in the form of a gaseous, liquid or solid working medium. An adiabatic partition 30 is installed between the cathode nozzle 6 of the capillary jet device 19 and the combustion chamber 29 of the engine 31, and it is opened when engine ignition is required and closed after the engine is ignited to isolate the influence of the high-temperature and high-pressure gas in the combustion chamber 29 on the capillary jet device 19.

[0012] In the pulse voltage generation circuit 9, the high-voltage end of the DC power supply U1 is connected to one end of the charging current-limiting resistor R C2 One end of the charging current-limiting resistor R C2 The other end is divided into two paths. One path is connected to one end of the trigger capacitor C2 as the high-voltage end of the trigger capacitor C2, and the other path is connected to the anode of the thyristor SCR2. The other end of the trigger capacitor C2, that is, the low-voltage end, is divided into two paths. One path is connected to the low-voltage end of the DC power supply U1, and the other path is connected to one end of the primary coil of the pulse transformer T1. The cathode of the thyristor SCR2 is connected to the other end of the primary coil of the pulse transformer T1. The anti-parallel diode VT2 is connected in parallel with the primary coil of the pulse transformer T1, its anode is connected to the low-voltage side of the trigger capacitor C2, and its cathode is connected to the cathode of the thyristor SCR2. The first trigger signal 21 of the thyristor trigger circuit 16 controls the gating of the thyristor SCR2 to control the discharge of the trigger capacitor C2 to the primary side of the pulse transformer T1. The high-voltage output end of the secondary side of the pulse transformer T1 is connected to one end of the DC-blocking capacitor C3. The other end of the DC-blocking capacitor C3 is led out and divided into two paths. One path is connected to one end of the saturable inductor L, and the other path is led out as the high-voltage output end of the pulse voltage of the pulse voltage generation circuit 9, which is connected to the trigger electrode 3 of the capillary discharge jet device 19. The other end of the wave-adjusting inductor L is connected to one end of the trigger loop current-limiting resistor R. The other end of the trigger loop current-limiting resistor R is divided into two paths. One path is connected to the low-voltage output end of the secondary side of the pulse transformer T1, and the other path is led out as the low-voltage output end of the pulse voltage of the pulse voltage generation circuit 9, which is connected to the front flange cover plate 5 of the capillary jet device 19.

[0013] The turns ratio of the primary and secondary coils of the pulse transformer T1 is 1:39.

[0014] In the pulse current generation circuit 10, the high and low voltage terminals of the energy storage capacitor C1 are respectively connected to the high and low voltage output terminals of the LC series resonance charging circuit 17. Before the start of a single discharge, the energy storage capacitor C1 is quickly charged to a preset voltage. The high voltage terminal of the energy storage capacitor C1 is connected to the anode of the thyristor SCR1, and the thyristor SCR1 and the diode VT1 are connected in antiparallel. Among them, the anode of the thyristor SCR1 is connected to the cathode of the diode VT1, and the cathode of the SCR1 is connected to the anode of the diode VT1. The cathode terminal of the thyristor SCR1 is led out as the high voltage output terminal of the pulse current generation circuit 10 and connected to the anode 2 of the capillary jet device 19. The thyristor trigger circuit 16 sends a second trigger signal 22 to the gate stage of the thyristor SCR1 to control the conduction of the thyristor SCR1 and control the discharge of the energy storage capacitor C1. The connection wire of the low voltage side of the energy storage capacitor C1 is led out as the low voltage output terminal of the pulse current generation circuit 10 and connected to the front flange cover 5 of the capillary jet device 19.

[0015] In the LC series resonance charging circuit 17, the primary part of the transformer T: The first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 in the N-channel IGBT module are connected in a bridge circuit. Among them, each IGBT module S i is connected in antiparallel with the diode D i . The collector of the IGBT module S i is connected to the cathode of the diode D i . The emitter of the IGBT module S i is connected to the anode of the diode D i , where i = 1, 2, 3, 4. The high voltage terminal of the DC power supply U2 is connected to the collectors of the first IGBT module S1 and the third IGBT module S3. The emitter of the first IGBT module S1 is connected to the collector of the second IGBT module S2. The emitter of the third IGBT module S3 is connected to the collector of the fourth IGBT module S4. The emitters of the third IGBT module S3 and the fourth IGBT module S4 are connected together and commonly connected to the low voltage side of the DC power supply U2. The gates of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 are respectively connected to the all-hardware drive controller 24. The all-hardware drive controller 24 respectively sends control signals to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 to control their conduction and turn-off. The emitter of the first IGBT module S1 is connected to one end of the resonance inductor L r . The other end of the resonance inductor L r is connected to one end of the resonance capacitor C r . One end of the resonance capacitor C rThe other end is connected to one end of the primary coil of transformer T, and the other end of the primary coil of transformer T is connected to the emitter of the third IGBT module S3; the secondary side of transformer T is connected to a diode full-bridge rectifier circuit composed of the first diode D5, the second diode D6, the third diode D7, and the fourth diode D8. The anode of the first diode D5 is connected to the cathode of the second diode D6, and the anode of the third diode D7 is connected to the cathode of the fourth diode D8. One end of the secondary side of transformer T is commonly connected to the anode of the first diode D5 and the cathode of the second diode D6, and the other end of the secondary side of transformer T is commonly connected to the anode of the third diode D7 and the cathode of the fourth diode D8. The cathode of the first diode D5 and the cathode of the third diode D7 are connected and connected to one end of the filter inductor L2. The other end of the filter inductor L2 is connected to the collector of the fifth IGBT module S5. The emitter of the fifth IGBT module S5 is connected to the high-voltage output end of the LC series resonance charging circuit. The gate of the fifth IGBT module S5 is connected to the all-hardware drive controller 24. The all-hardware drive controller 24 controls the on and off of the fifth IGBT module S5 to control the on and off of the output circuit; the negative-polarity output end of the diode full-bridge rectifier circuit is connected to the low-voltage output end of the LC series resonance charging circuit module. A resistor divider 26 composed of the first resistor R1 and the second resistor R2 is connected in parallel between the high- and low-voltage output ends of the LC series resonance charging circuit. One end of the first R1 is connected to the high-voltage output end, and the other end is connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to the low-voltage output end and is connected to the anodes of the second diode D6 and the fourth diode D8; the voltage signal divided by the resistor divider 26 is input into the opto-isolation module 25 and is input into the all-hardware drive controller 24 after signal isolation; at the same time, the control signal 23 from the control system 18 controls the operation of the all-hardware drive controller 24 and controls the start and stop of the PWM signals for driving the bridge arms of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 and the on and off of the fifth IGBT module S5.

[0016] The resistance value of the first resistor R1 is 1334 times that of the second resistor R2.

[0017] The preparation method of the energetic doped working medium block 1 is as follows:

[0018] Mix the nano- to micron-sized active metal powder with the micron-sized polymer powder in a certain proportion. The active metal powder accounts for 3%-26% of the total powder mass, or dope some active metal oxide powder to improve the mechanical properties of the energetic working medium block, or add a small amount of ammonium perchlorate powder to increase the chemical energy released by the reaction. After placing all the powders in a blender and shear-mixing them evenly, put them into a cylindrical hydraulic press mold with a hole in the middle, complete the filling at one time, apply pressure and maintain it, and then slowly and gradually release the pressure of the hydraulic press to make a cylindrical blank with a through hole in the middle. Let it stand to eliminate internal stress, and then sinter it in an argon protection atmosphere. First, heat it at a heating rate of 50 degrees Celsius per hour to 370-390 degrees Celsius, keep it warm for 2-6 hours, then cool it at a cooling rate of 50 degrees Celsius per minute to 327 degrees Celsius, keep it warm for 2 hours, and then reduce the temperature to room temperature at a cooling rate of 50 degrees Celsius per minute. Finally, through machining, process the capillary channel 12 at the axis position of the working medium block, and vertically and inwardly process a cylindrical channel 14 on the side of the cylindrical working medium block to communicate with the capillary channel 12.

[0019] The active metal powder is aluminum powder or boron powder; the polymer powder is polytetrafluoroethylene, high-density polyethylene or polyether ether ketone.

[0020] The no-load output voltage of the pulse voltage generation circuit 9 is 39 kV. When the breakdown voltage required to trigger the spark gap 15 is higher than the output voltage of the pulse voltage generation circuit 9, the plasma jet ignition device cannot work because it cannot trigger the capillary discharge plasma jet.

[0021] An interlocking structure in which the insulator 4 first gradually expands and then has an equal diameter inside the energetic doped working medium block 1 is adopted between the energetic doped working medium block 1 and the insulator 4 to increase the creepage distance and the outer creepage distance of the insulator 4, preventing flashover discharge from occurring at other positions except the spark gap 15 and resulting in trigger failure.

[0022] The working method of the repetitive frequency plasma jet ignition system using the energetic modified working medium repetitively generates plasma jets at a set frequency. In each cycle, the control system 18 controls the DC power supply U2 in the LC series resonance charging circuit to start charging by sending a charging start signal 23 to the all-hardware drive controller 24 in the LC series resonance charging circuit 17; the control system 18 inputs a turn-on signal 20 to the thyristor trigger circuit 16 at a set frequency to trigger a single capillary discharge to generate a plasma jet. Each cycle of generating a plasma jet is divided into two steps: energy storage system charging and pulse discharge to generate a plasma jet.

[0023] 1) Charging process of the energy storage system: The control system 18 sends a charging start signal 23 to the all-hardware drive controller 24 in the LC series resonance charging circuit 17, and the LC series resonance charging circuit 17 starts to work; the all-hardware drive controller 24 inputs complementary PWM drive signals with a duty cycle of 25% to the first IGBT module S1 and the third IGBT module S3 as a group, and the second IGBT module S2 and the fourth IGBT module S4 as a group, controlling the bridge arms to turn on alternately; the direct current provided by the DC power supply U2 is converted into alternating current, stepped up by the transformer T, and then converted into direct current again through the diode full-bridge rectifier circuit, realizing the charging of the energy storage capacitor C1 to a high voltage of up to 2000V; the resistor voltage divider 26 connected to the output terminal collects the voltage of the energy storage capacitor C1, divides the 0-2000V voltage of the energy storage capacitor C1 into a voltage signal of 0-1.5V, inputs it into the all-hardware drive controller 24 through the opto-isolation module 25, compares it with the set charging voltage through the operational amplifier circuit, and judges whether the voltage of the energy storage capacitor C1 reaches the preset voltage through the gate circuit group. When the voltage of the energy storage capacitor C1 reaches the set charging voltage, the all-hardware drive controller stops inputting drive PWM signals to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4, and controls the fifth IGBT module S5 to turn off the charging circuit;

[0024] 2) Process of generating plasma jet by pulsed discharge: When reaching the trigger discharge moment, the control system 18 transmits a trigger plasma jet signal to the thyristor trigger circuit 16; the thyristor trigger circuit 16 transmits a second trigger signal 22 to the thyristor SCR1 in the pulsed current generation circuit 10, controlling its conduction, applying the voltage of the energy storage capacitor C1 between the anode 2 and the front flange cover 5. During the discharge process, the front flange cover 5 serves as the cathode; after a delay, the thyristor trigger circuit 16 inputs a first trigger signal 21 to the thyristor SCR2 in the pulsed voltage generation circuit, controlling its conduction, applying a trigger high voltage pulse to the trigger electrode 3, and inducing surface discharge in the trigger channel 15 between the end of the anode 2 and the end of the trigger electrode 3;

[0025] The trigger channel 15 discharges along the surface to form an arc, and the high-conductivity plasma formed by ablating the capillary wall material of the trigger channel 15 moves toward the front flange cover plate 5 serving as the cathode. When the plasma reaches the cathode front flange cover plate 5, the capillary channel between the anode 2 and the cathode front flange cover plate 5 is filled with high-conductivity plasma, and the channel between the anode 2 and the cathode front flange cover plate 5, that is, the high voltage output end and the low voltage output end of the pulse current generating circuit 10 are short-circuited, and a discharge loop from the high voltage output end of the pulse current generating circuit 10 - anode 2 - arc in the capillary channel 12 - cathode front flange cover plate 5 - low voltage output end of the pulse current generating circuit 10 is formed, and the electric energy stored in the energy storage capacitor in the pulse current generating circuit 10 begins to be released through the arc load in the capillary channel 12, and the high-temperature arc radiation energy causes the energetic doping material of the capillary wall of the solid working fluid to ablate to form a high-temperature and high-pressure plasma, and the active metal powder and the polymer powder components in the plasma undergo a chemical reaction to release energy, further increasing the internal energy of the plasma jet. The inner wall material of the capillary channel 12 of the energetic doping working medium block 1 continuously changes phase and decomposes into the interior of the capillary channel 12, increasing the pressure inside the cavity, so that the plasma continuously moves toward the cathode nozzle 6 under the action of the pressure gradient, and finally ejects outward to generate a high-temperature and high-density plasma jet 13;

[0026] The heavy-frequency plasma jet ignition system triggers the capillary channel 12 between the anode 2 and the front flange cover 5 through plasma injection. The mass of the working fluid block and the electrode ablation in a single discharge is from several milligrams to tens of milligrams. There is no obvious change in its morphology after a single discharge. The next discharge starts immediately after the pulse current generating circuit 10 completes energy storage.

[0027] The above process is repeated to repeatedly draw out the plasma jet at a set frequency until the propellant 28 is ignited, and the insulation baffle 30 is closed. When the next ignition time arrives, the insulation baffle 30 is opened and the above process is repeated to achieve repeated ignition of the engine.

[0028] The present invention improves the energy of a single jet by doping active metal into a polymer working fluid block, utilizes the chemical energy release of plasma, and improves the ignition efficiency of the jet device through the heat accumulation effect by operating the jet device in a repetitive frequency mode.

[0029] Although there are some reproducible capillary discharge plasma devices with two-gap structures, such as the patent "A combination wave circuit for driving ablation capillary discharge, patent number CN201610256978.3" and the paper "Experimental study on transient high heat load generated by capillary discharge plasma", the present invention is different from these reproducible two-gap capillary jet devices in terms of working fluid type, structural design, application occasions and control logic:

[0030] (1) In terms of the working fluid type, the existing capillary discharge jet device that can be repeatedly operated uses ordinary polymer working fluids such as polyethylene and polytetrafluoroethylene. During the ablation formation process, a large amount of arc energy is required to dissociate chemical bonds, vaporize, and ionize the polymer compound to generate plasma. However, the modified polytetrafluoroethylene working fluid doped with aluminum and boron with nano- to micron-sized particles in the present invention can release chemical energy through chemical reactions caused by high temperature during the ablation process, which can compensate for part of the energy loss during the ablation process and increase the jet energy at the same time. The reaction equation is:

[0031] 4Al + 3C2F4 = 4AlF3 + 6C + Q1

[0032] Where Q1 is the heat released by the reaction, and the energy release can reach 14.9 kJ / g.

[0033] (2) In terms of the device structure, the existing two-gap jet device that can be repeatedly operated has a short gap between the trigger electrode and the anode, generally only 2-3 mm, and the voltage of the trigger electrode is not high, generally not exceeding 20 kV. When the discharge electrode is ablated and shortened multiple times, the trigger gap increases, and the breakdown voltage gradually increases. When the length of the trigger gap increases to a value where the required trigger voltage is higher than the peak value of the input voltage of the trigger electrode, breakdown cannot occur, which limits the number of uses. In addition, the insulation between the electrode and the outer shell is not strengthened. However, the device of the present invention takes into account the factor of the ablation and shortening of the electrode and the lengthening of the trigger electrode, raises the trigger electrode voltage to 39 kV, and uses an interlocking contact surface structure to strengthen the inner and outer surface lengths of the trigger electrode insulator to prevent flashover along the surface between the electrode and the outer shell. The high trigger voltage can achieve a longer trigger gap for breakdown, well adapting to the process of the ablation of the electrode and the lengthening of the trigger gap, and enabling more repeated discharges.

[0034] (3) In terms of the application background, the existing two-gap jet device that can be repeatedly operated is applied to fields such as long air gap conduction and high heat load simulation, while the capillary plasma jet device of the present invention is applied to the ignition field of aerospace propulsion systems.

[0035] The preparation method of the energetic doped polymer working fluid is mentioned in documents such as the paper "Theoretical and Experimental Research on the Working Process and Working Fluid Modification of Pulse Plasma Thrusters", but the working fluid block structure, working environment, and doping purpose in this paper are essentially different from those of the present invention.

[0036] In the paper "Theoretical and Experimental Research on the Working Process of Pulse Plasma Thruster and the Modification of Working Medium", the modified working medium block is applied to the pulse plasma thruster. The structure of the working medium block is a cuboid, and it works in a vacuum environment. By doping, the conductivity of the ablated plasma is changed, and then the current flowing through the plasma is changed. The purpose is to change the thrust parameters of the thruster. However, the working medium block of the present invention is applied to a capillary-type plasma jet igniter, and is made into a coaxial structure with capillary through holes. During the discharge process, the pressure in the capillary of the working medium block can reach the order of several megapascals. The purpose of doping is to increase the jet energy by exothermic chemical reactions.

[0037] The paper "Experimental Research on the Generation of Transient High Heat Flux Based on Capillary Discharge Plasma" relies on a 10-way parallel energy storage system and switches to discharge the gaps in sequence to achieve repetitive operation. The present invention uses an LC series resonance charging system to achieve repetitive operation of the jet system by repeatedly charging and discharging a single capacitor quickly. This reduces the mass and quantity of circuit components and the complexity of the system. Using a pure hardware control and drive circuit, it avoids the situation of the microcontroller being locked in a strong interference environment, improves the anti-interference ability of the system, reduces the possibility of its failure under extreme conditions, and makes it more suitable for the aerospace field with strict reliability requirements.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. The present invention uses an LC series resonance charging circuit to charge and discharge a single energy storage capacitor at high speed to achieve repetitive operation of the system, simplifies the circuit topology, reduces the number of circuit components, reduces the system mass, and can achieve repetitive operation at higher frequencies. Using a full hardware drive circuit and control system, the capillary jet device is a fully solid working medium, without an ignition material storage and supply device and mechanism, and does not require complex gas paths, valves, gas cylinders and other devices. The system is simple and reliable, reducing the possibility of the system failing in a strong interference environment.

[0040] 2. The present invention uses an energetic doped polymer material as the working medium of the igniter. Through the co-ablative entry of the polymer and active metal powder into the plasma, the two undergo a chemical reaction at high temperature to release chemical energy, which compensates to a certain extent for the energy absorbed by the ablation of the capillary wall material, increases the internal energy of the plasma jet, and improves the ignition efficiency.

[0041] 3. The capillary jet device part of the present invention increases the trigger electrode voltage, improves the insulation strength of the inner and outer surfaces of the insulator, improves the adaptability to the ablation of the electrode and the elongation of the trigger gap, can break down a larger length of the trigger gap to cause capillary discharge, increases the number of working times of the device, and can be more suitable for high-repetition frequency and multiple-discharge working conditions;

[0042] 4. The capillary jet device is designed with a three - electrode structure and triggered by plasma jet. After each discharge, the device structure shows no obvious change, enabling the jet device to operate repeatedly. It can achieve reliable multiple ignitions and flexible control of the ignition moment in the aerospace propulsion system. By multiple energy storage and release and controlling the ignition moment, the engine can achieve multiple ignitions and flexible control of the ignition moment, improving the intelligent level of the engine. Description of the Drawings

[0043] Figure 1 Schematic diagram of a repetitive - frequency plasma jet ignition system using an energetic modified working medium according to the present invention.

[0044] Figure 2 Schematic diagram of the positions of the capillary channels of the energetic - doped working medium block and the cylindrical through - holes on the side.

[0045] Figure 3 Schematic diagram of the pulse voltage generation circuit.

[0046] Figure 4 Schematic diagram of the pulse current generation circuit.

[0047] Figure 5 Schematic diagram of the series - resonant charging circuit.

[0048] Figure 6 Flow chart of the ignition system for achieving repetitive - frequency capillary discharge.

[0049] Figure 7 Schematic diagram of the bite - type structure of the trigger electrode, insulator at the anode and the working medium block to enhance the surface insulation length and enhance the surface insulation.

[0050] Figure 8 In (a) to (b) is a schematic diagram of the change in electrode ablation, electrode shortening and trigger gap lengthening during multiple discharges.

[0051] Figure 9 Sintering temperature curve of the energy - enhanced working medium.

[0052] Figure 10 Flow chart for preparing the energy - enhanced capillary discharge working medium block.

[0053] Figure 11 Typical discharge voltage - current waveform diagram of the pulsed thermal plasma jet device using an aluminum - based energetic working medium.

[0054] Figure 12 Voltage waveform diagram of the series - resonant charging circuit charging the energy - storage capacitor C1.

[0055] Figure 13 Voltage - current waveform diagram of charging and discharging at a repetition frequency of 20 Hz using an aluminum - based energetic working medium. Detailed Implementation Modes

[0056] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] As Figure 1 shown, a repetitive plasma jet ignition system using an energetic modified working medium includes six modules: a capillary jet device 19, a pulse voltage generation circuit 9, a pulse current generation circuit 10, a thyristor trigger circuit 16, an LC series resonance charging circuit 17, and a control system 18, which are connected to an engine 31.

[0058] Among them, an energy - enhancing modified working medium is used in the capillary jet device 19, which can operate repeatedly. It includes an energetic doped working medium block 1. As Figure 2 shown, the energetic doped working medium block 1 is made by mixing aluminum powder or boron powder from the micron - scale to the nano - scale with polymer powders such as polytetrafluoroethylene, high - density polyethylene, and polyether ether ketone, pressing, sintering, and machining into a modified energetic working medium. A capillary channel 12 is machined at the axis, and a cylindrical channel 14 is machined on the side to communicate with the capillary channel 12. The energetic doped working medium block 1 is coaxially installed inside a housing 8. The front of the housing 8 is connected to a front flange cover plate 5, and the rear is connected to a rear flange cover plate 7. The front flange cover plate 5 is coaxially machined with an expanding cathode nozzle 6. The anode 2 is inserted into the capillary channel 12 from the rear of the energetic doped working medium block 1, and the trigger electrode 3 is inserted into the capillary channel 12 from the cylindrical channel 14 on the side of the energetic doped working medium block 1. The capillary channel 12 between the end of the anode 2 and the front flange cover plate 5 is divided into two parts: the part between the anode 2 and the trigger electrode 3, called the trigger channel 15, and the part between the trigger electrode 3 and the front flange cover plate 5. Insulators 4 are installed outside the anode 2 and the trigger electrode 3 to achieve electrical isolation from the housing. A limit screw 11 is installed outside the insulator 4 and fixedly connected to the housing 8.

[0059] As Figure 1As shown in the figure, the connection relationships of each module of the entire ignition system of the present invention are as follows: The high-voltage output terminal of the pulse voltage generation circuit 9 is connected to the trigger electrode 3 of the capillary jet device 19, and the low-level output terminal is connected to the front flange cover plate 5 of the capillary jet device 19; the high-voltage output terminal of the pulse current generation circuit 10 is connected to the anode 2 of the capillary jet device 19, and the low-voltage output terminal is connected to the front flange cover plate 5 of the capillary jet device 19. The front flange cover plate 5 of the capillary jet device 19 is grounded through a ground wire; the high-voltage output terminal of the LC series resonance charging circuit 17 is connected to the high-voltage end of the energy storage capacitor C1 in the pulse current generation circuit 10, and the low-voltage output terminal is connected to the low-voltage end of the energy storage capacitor C1 in the pulse current generation circuit 10 to achieve rapid charging of the energy storage capacitor C1; the two drive voltage output terminals of the thyristor trigger circuit 16 are respectively connected to the thyristor SCR2 in the pulse voltage generation circuit 9 and the thyristor SCR1 in the pulse current generation circuit 10 to turn on the two thyristors; the control system 18 is connected to the LC series resonance charging circuit 17 and the thyristor trigger circuit 16 through optical fibers, and sends a charging start signal 23 to the LC series resonance charging circuit 17 and a trigger signal 20 to the thyristor trigger circuit 16 according to the set frequency.

[0060] When applied to the ignition of the engine in the propulsion system, the capillary jet device 19 in the repetitive pulse plasma jet generation system is connected to the end of the outer shell 27 of the engine 31. The interior of the engine outer shell 27 is filled with a propellant 28, and the propellant can be in the form of gas, liquid or solid. An adiabatic partition 30 is installed between the cathode nozzle 6 of the capillary jet device 19 and the combustion chamber 29 of the engine 31, which is opened when engine ignition is required and closed after the engine is ignited to isolate the influence of the high-temperature and high-pressure gas in the combustion chamber 29 on the capillary jet device 19.

[0061] As Figure 3 shown, in the pulse voltage generation circuit 9, the voltage of the DC power supply U1 is 800V, the charging current-limiting resistor R C2 has a resistance value of 10Ω, and the capacitance of the trigger capacitor C2 is 2.5 μF. The high-voltage end of the DC power supply U1 is connected to one end of the charging current-limiting resistor R C2 and R C2The other end is divided into two paths. One path is connected to one end of the trigger capacitor C2, serving as the high-voltage end of the trigger capacitor C2, and the other path is connected to the anode of the thyristor SCR2. The connection line of the other end (low-voltage end) of the trigger capacitor C2 is divided into two paths. One path is connected to the low-voltage end of the DC power supply U1, and the other path is connected to one end of the primary coil of the pulse transformer T1. The cathode of the thyristor SCR2 is connected to the other end of the primary coil of the pulse transformer T1. The antiparallel diode VT2 is connected in parallel with the primary coil of the pulse transformer T1, with its anode connected to the low-voltage side of the trigger capacitor C2 and its cathode connected to the cathode of the thyristor SCR2. The first trigger signal 21 of the thyristor trigger circuit 16 controls the gating of the thyristor SCR2 to control the discharge of the trigger capacitor C2 to the primary side of the pulse transformer T1. The turns ratio of the primary and secondary coils of the pulse transformer T1 is 1:39. The high-voltage output end of the secondary side of the pulse transformer T1 is connected to one end of the DC-blocking capacitor C3 with a capacitance of 2.6 nF. The connection line of the other end of the DC-blocking capacitor C3 is divided into two paths. One path is connected to one end of the saturable inductor L, and the other path is led out as the high-voltage output end of the pulse voltage of the pulse voltage generation circuit 9, which is connected to the trigger electrode 3 of the capillary discharge jet device 19. The other end of the wave-tuning inductor L is connected to one end of the trigger loop current-limiting resistor R. The other end of the trigger loop current-limiting resistor R is divided into two paths. One path is connected to the low-voltage output end of the secondary side of the pulse transformer T1, and the other path is led out as the low-voltage output end of the pulse voltage of the pulse voltage generation circuit 9, which is connected to the front flange cover 5 of the capillary jet device 19.

[0062] As Figure 4 shown, in the pulse current generation circuit 10, the typical charging voltage of the energy storage capacitor C1 is 2 kV, the capacitance value of the energy storage capacitor is adjustable from 140 μF to 560 μF, and the energy storage is 280 J - 1120 J. Its high- and low-voltage ends are respectively connected to the high- and low-voltage output ends of the LC series resonance charging circuit 17. The energy storage capacitor C1 is quickly charged to the preset voltage before the single discharge starts. The high-voltage end of the energy storage capacitor C1 is connected to the anode of the thyristor SCR1, and the thyristor SCR1 and the diode VT1 are connected in antiparallel, where the anode of the thyristor SCR1 is connected to the cathode of the diode VT1, and the cathode of the thyristor SCR1 is connected to the anode of the diode VT1. The cathode end of the thyristor SCR1 is led out as the high-voltage output end of the pulse current generation circuit 10 and is connected to the anode 2 of the capillary jet device 19. The trigger signal 22 of the thyristor trigger circuit 16 is connected to the gate of the thyristor SCR1 to control the conduction of the thyristor SCR1 and the discharge of the energy storage capacitor C1. The connection line of the low-voltage side of the energy storage capacitor C1 is led out as the low-voltage output end of the pulse current generation circuit 10 and is connected to the front flange cover 5 of the capillary jet device 19.

[0063] As Figure 5As shown, in the LC series resonant charging circuit 17, the turns ratio of the primary and secondary sides of the transformer T is 6:48. In its primary part, the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 in the N-channel IGBT module are connected in a bridge configuration, where each IGBT module S i is anti-parallel connected to the diode D i . The collector of the IGBT module S i is connected to the cathode of the diode D i , and the emitter of the IGBT module S i is connected to the anode of the diode D i (i = 1, 2, 3, 4). The voltage of the DC power supply U2 is 360V and the power is 12kW. The high-voltage end is connected to the collectors of the first IGBT module S1 and the third IGBT module S3. The emitter of the first IGBT module S1 is connected to the collector of the second IGBT module S2. The emitter of the third IGBT module S3 is connected to the collector of the fourth IGBT module S4. The emitters of the third IGBT module S3 and the fourth IGBT module S4 are connected together and jointly connected to the low-voltage side of the DC power supply U2. The gates of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 are respectively connected to the all-hardware drive controller 24, and the all-hardware drive controller 24 sends control signals to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4 respectively to control their turn-on and turn-off. The emitter of the first IGBT module S1 is connected to one end of the resonant inductor L r , and the other end of the resonant inductor L r is connected to one end of the resonant capacitor C r , and the other end of the resonant capacitor C rThe other end is connected to one end of the primary coil of transformer T, and the other end of the primary coil of transformer T is connected to the emitter of the third IGBT module S3. The secondary side of transformer T is connected to a diode full-bridge rectifier circuit composed of a first diode D5, a second diode D6, a third diode D7, and a fourth diode D8. The anode of the first diode D5 is connected to the cathode of the second diode D6, and the anode of the third diode D7 is connected to the cathode of the fourth diode D8. One end of the secondary side of transformer T is commonly connected to the anode of the first diode D5 and the cathode of the second diode D6, and the other end of the secondary side of transformer T is commonly connected to the anode of the third diode D7 and the cathode of the fourth diode D8. The cathode of the first diode D5 and the third diode, the cathode of D7 are connected and connected to one end of the filter inductor L2. The other end of the filter inductor L2 is connected to the collector of the fifth IGBT module S5. The emitter of the fifth IGBT module S5 is connected to the high-voltage output terminal of the LC series resonant charging circuit. The gate of the fifth IGBT module S5 is connected to the all-hardware drive controller 24. The all-hardware drive controller 24 controls the on and off of the fifth IGBT module S5 to control the on and off of the output circuit; the negative output terminal of the diode full-bridge rectifier circuit is connected to the low-voltage output terminal of the LC series resonant charging circuit module. A resistor divider 26 composed of a first resistor R1 and a second resistor R2 is connected in parallel between the high- and low-voltage output terminals of the LC series resonant charging circuit. One end of the first R1 is connected to the high-voltage output terminal, the other end is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the low-voltage output terminal and connected to the anodes of the second diode D6 and the fourth diode D8; the voltage signal divided by the resistor divider 26 is input into the opto-isolation module 25 and input into the all-hardware drive controller 24 after signal isolation; at the same time, the control signal 23 from the control system 18 controls the operation of the all-hardware drive controller 24, controls the start and stop of the PWM signals for driving the bridge arms of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4, and the on and off of the fifth IGBT module S5.

[0064] Among them, the capillary jet device 19 uses an energetic doped working medium block 1, such as Figure 2 shown, and its preparation method is as Figure 10 shown:

[0065] Mix aluminum powder with nano- to micron-sized particles and polytetrafluoroethylene powder with a micron particle size in a certain proportion. The aluminum powder accounts for 3%-26% of the total powder mass. Other materials can be added, including doping part of the alumina powder to improve the mechanical properties of the energetic working medium block, or adding a small amount of ammonium perchlorate (AP) powder to increase the chemical energy released by the reaction. The reaction equation between aluminum powder and polytetrafluoroethylene at high temperature is:

[0066] 4Al + 3C2F4 = 4AlF3 + 6C + Q1

[0067] Among them, Q1 is the heat released by the reaction, and the energy release can reach 14.9 kJ / g.

[0068] After placing all the powders in a blender and shear-mixing them evenly, they are put into a cylindrical hydraulic press mold with a hole in the middle. The filling is completed at one time, and it is kept under a pressure of 20 Mpa for 5 minutes. Then, the pressure of the hydraulic press is slowly and gradually removed to make a cylindrical blank with a through-hole in the middle. It is left standing for 24 hours to eliminate internal stress, and then it is sintered in a tubular furnace under an argon protection atmosphere. The temperature curve is set as Figure 9 shown: First, it is heated to 380 °C at a heating rate of 50 °C per hour and kept warm for 6 hours. Then, it is cooled to 327 °C at a cooling rate of 50 °C per minute and kept warm for 2 hours. Then, it is cooled to room temperature at a cooling rate of 50 °C per minute. This can not only ensure that the polytetrafluoroethylene is fully melted and the powder is evenly mixed, but also ensure the crystallinity of the sample after cooling to ensure sufficient mechanical strength. Finally, through machining, a capillary channel 12 is machined at the axial center position of the working medium block, with a diameter range of 1 - 10 mm and a length range of 10 - 100 mm, for inserting into the anode 2. And a cylindrical channel 14 with a diameter of 1 - 5 mm is vertically machined inward on the side of the cylindrical working medium block. The depth of the through-hole is equal to the radius of the capillary working medium block, and the distance from the position where the through-hole is machined to one bottom surface of the cylindrical working medium block is 25 mm. For inserting the trigger electrode 3 in the middle.

[0069] Figure 1 In, the characteristics and connection methods of each device inside the capillary jet device 19 are as follows:

[0070] Figure 1 In, the cathode nozzle 6, the cathode nozzle 6 and the front flange cover 5 are of an integrated structure, used for the front limit fixation of the energetic doped working medium block 1 and simultaneously serving as the cathode of the discharge circuit; the through-hole diameter of the cathode nozzle 6 close to the front flange cover 5 is the same as the diameter of the capillary channel 12 in the energetic doped working medium block 1. The cathode nozzle 6 adopts a conical expansion shape with a cone angle of 5° - 15°, used to increase the plasma jet velocity and better restrict its expansion, making the plasma jet energy more concentrated. The front flange cover 5 and the outer shell 8 are connected by a bolt-flange structure.

[0071] Figure 1 In, the outer shell 8, adopts a coaxial structure design, the material is stainless steel, and the thickness is 4 mm, to provide sufficient mechanical strength; its internal diameter is the same as the diameter of the energetic doped working medium block 1, so that the two can be closely fitted, and the length is the same as that of the energetic doped working medium block 1. A threaded hole is machined at the same position as the through-hole for inserting the trigger electrode in the middle of the energetic doped working medium block, for installing the side trigger electrode and insulator. Flange structures are machined on both sides, for connecting with the front flange cover 5 and the rear flange cover 7 through bolts.

[0072] Figure 1Among them, the trigger electrode 3, made of brass or copper tungsten alloy, is arranged on the outer shell 8, and the end of the electrode extends into the energetic doped working medium block 1. Its length makes its end face contact with the wall of the middle capillary channel 12 of the energetic doped working medium block 1, and is insulated from the outer shell 8 through the insulator 4.

[0073] Figure 1 Among them, the insulator 4 uses insulating materials such as nylon, polyether ether ketone, and alumina ceramics, and is fixedly pressed against the outer shell 8 through the limiting screw 11 made of stainless steel. Its bottom is connected to the energetic doped working medium block 1 through an interlocking structure, such as Figure 7 As shown, the internal surface insulation path from the high-potential electrode to the low-potential limiting screw and the outer shell part is the broken line ABCD. Through the design of the interlocking structure, the surface distance is maximally increased in the limited space inside the working medium block, the flashover voltage is increased, and the unexpected discharge phenomenon of insulation failure is prevented, resulting in the failure of triggering the capillary discharge plasma jet. As Figure 7 As shown, the external surface insulation path is EFG, and the external flashover discharge is prevented by increasing the height of the insulator 4.

[0074] Through the insulation strengthening design of the structure of the insulator 4, not only can the compactness of the device be improved, the volume and weight be reduced, but also the voltage that the trigger electrode can withstand can be increased without unexpected discharge. After multiple discharges, the anode 2 and the trigger electrode 3 are ablated by the arc, and the length is continuously shortened. For the repetitive discharge condition, the number of discharges is significantly increased, and the electrode ablation phenomenon is more significant. The length of the trigger gap 15 between the end of the anode 2 and the end of the trigger electrode 3 gradually becomes longer, and the required breakdown voltage gradually increases. As Figure 8 As shown, Figure 8 In (a) among them, HI is the trigger gap in the initial state, Figure 8 In (b) among them, KJ is the trigger gap after multiple discharges. Figure 1 In the high-pulse voltage design of the external circuit pulse voltage generation circuit 9, the output trigger voltage amplitude can reach 39 kV, and the breakdown of the trigger gap below 13 mm can be achieved without insulation failure. It has good adaptability to the extension of the trigger gap caused by electrode ablation, can achieve more discharges, and extend the life of the jet device.

[0075] Figure 1 Among them, the rear flange cover 7 is designed with a flange structure the same as that of the outer shell, and is connected to the outer shell 8 through a bolt-flange structure. A threaded hole is machined at its axial center, which matches the limiting screw 11.

[0076] Figure 1 Among them, the anode 2 is inserted into the tail of the capillary channel 12 of the energetic doped working medium block 1, has the same structure and material as the trigger electrode 3, is also insulated from the rear flange cover 7 through the insulator 4, and the insulator 4, the anode 2 and the rear flange cover 7 are fixed through the limiting screw 11.

[0077] Figure 1 In it, at the end of the anode 2, the end of the trigger electrode 3 and the surface along the cavity of the energetic doped working medium block 1 form a trigger gap 15.

[0078] Figure 1 In it, the trigger electrode 3 and the front flange cover plate 5 are connected to the pulse voltage generating circuit 9 through wires. The trigger electrode 3 is connected to the high-level output of the pulse voltage generating circuit, and the front flange cover plate 5 is connected to the ground terminal of the pulse voltage generating circuit.

[0079] Figure 3 In it, the pulse voltage generating circuit 9 outputs a pulse voltage with an open-circuit amplitude of 39 kV and a pulse width of 500 ns.

[0080] Figure 1 In it, the anode 2 and the front flange cover plate 5 are respectively connected to the high-level and ground terminals of the pulse current generating circuit 10 through wires. In the pulse current generating circuit 10, a high-energy density metallized film capacitor is used for electric energy storage, and the on-off is controlled by the thyristor SCR1. The typical charging voltage is 2 kV, the capacitance value of the energy storage capacitor is adjustable from 140 μF to 560 μF, and the energy storage is 280 J - 1120 J. An arc is formed by pulsed discharge through the capillary channel 12, ablating the capillary wall material to form a high-temperature and high-pressure plasma, which is ejected from the cathode nozzle 6 to form a high-temperature and high-density plasma jet 13.

[0081] The repetitive plasma jet ignition system using an energetic modified working medium can repeatedly generate plasma jets at a set frequency, and its working timing diagram is as Figure 6 shown, and its working process is as follows:

[0082] Within each cycle T time, the control system 18 controls the DC power supply U2 in the LC series resonance charging circuit 17 to start charging by sending a charging start signal 23 to the all-hardware drive controller 24 in the LC series resonance charging circuit; the control system inputs a trigger plasma jet opening signal 20 to the thyristor trigger circuit 16 at a set frequency to trigger a single capillary discharge to draw out the plasma jet. When the opening signal 20 is sent, the charging start signal 23 is interrupted for 580 μs to ensure that after the plasma jet is drawn out, the LC series resonance charging circuit is controlled to start working again. Each cycle of generating the plasma jet can be divided into two steps: energy storage system charging and pulsed discharge to generate the plasma jet.

[0083] 1) Charging process of the energy storage system: The control system 18 controls the LC series resonant charging circuit 17 to start working by sending a charging start signal 23 to the all-hardware drive controller 24 in the LC series resonant charging circuit 17. This signal lasts for the time T of the entire discharge cycle until the thyristor control turn-on signal 20 is sent and then stops. The all-hardware drive controller 24 inputs complementary PWM drive signals with a duty cycle of 25% to the first IGBT module S1 and the third IGBT module S3 as a group, and the second IGBT module S2 and the fourth IGBT module S4 as a group. The frequency of the PWM drive signal is the same as the circuit resonance period, which is set to 18.3 kHz, to control the bridge arms to turn on alternately. The direct current provided by the DC power supply U2 is converted into alternating current, stepped up by the transformer T, and then converted back into direct current through the diode full-bridge rectifier circuit, so as to charge the energy storage capacitor C1 to a high voltage of up to 2000V. The resistor voltage divider 26 connected to the output terminal, with a voltage division ratio of 1334:1, collects the voltage of the energy storage capacitor C1, divides the 0 - 2000V voltage of the energy storage capacitor C1 into a voltage signal of about 0 - 1.5V, and inputs it into the all-hardware drive controller 24 through the optoelectronic isolation module 25. It is compared with the set charging voltage through the operational amplifier circuit, and the gate circuit group judges whether the voltage of the energy storage capacitor C1 reaches the preset voltage. When the voltage of the energy storage capacitor C1 reaches the set charging voltage, the all-hardware drive controller 24 stops inputting the drive PWM signal to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3, and the fourth IGBT module S4, and controls the fifth IGBT module S5 to turn off the charging circuit. In the system of the present invention, when the capacitance of the energy storage capacitor C1 in the pulse current generation circuit is 140 μF, the LC series resonant charging circuit 17 can charge it to 2000V in about 32.5 ms. The voltage waveform of the energy storage capacitor C1 during the charging process is as Figure 12 shown.

[0084] 2) Process of generating plasma jet by pulsed discharge: When a repetition frequency period T elapses and the trigger discharge moment is reached, the control system 18 transmits a trigger signal 20 for controlling the thyristor to turn on to the thyristor trigger circuit 16. The duration of this signal is 20 μs. At the same time, the charging start signal 23 is stopped for 580 μs, so that the LC series resonant charging circuit stops working during the whole process of extracting the capillary discharge plasma jet; the thyristor trigger circuit 16 transmits a second trigger signal 22 to the thyristor SCR1 in the pulsed current generating circuit 10 to control its conduction, and applies the voltage of the energy storage capacitor C1 between the anode 2 and the front flange cover 5. During the discharge process, the front flange cover 5 serves as the cathode; after a delay of 5 μs, the thyristor trigger circuit 16 inputs a first trigger signal 21 to the thyristor SCR2 in the pulsed voltage generating circuit to control its conduction, and applies a trigger high-voltage pulse to the trigger electrode 3. Its amplitude is 39 kV and the pulse width is 500 ns, inducing a surface discharge to occur in the trigger channel 15 between the end of the anode 2 and the end of the trigger electrode 3.

[0085] The surface discharge in the trigger channel 15 forms an arc, and the high-conductivity plasma formed by ablating the capillary wall material of the trigger channel 15 moves towards the front flange cover 5 serving as the cathode. When the plasma reaches the cathode front flange cover 5, the capillary channel between the anode 2 and the cathode front flange cover 5 is filled with high-conductivity plasma. The channel between the anode 2 and the cathode front flange cover 5, that is, the high-voltage output terminal and the low-voltage output terminal of the pulsed current generating circuit 10, are short-circuited. A discharge loop is formed from the high-voltage output terminal of the pulsed current generating circuit 10 - anode 2 - arc in the capillary channel 12 - cathode front flange cover 5 - low-voltage output terminal of the pulsed current generating circuit 10. The electrical energy stored in the energy storage capacitor in the pulsed current generating circuit 10 starts to be released through the arc load in the capillary channel 12. The high-temperature arc radiation energy ablates the energy-containing doped working medium material on the inner wall of the capillary channel 12 of the solid working medium to form a high-temperature and high-pressure plasma. The active components such as aluminum powder in the plasma react chemically with the polytetrafluoroethylene (PTFE) component to release energy, further increasing the internal energy of the plasma jet. The inner wall material of the capillary channel 12 of the energy-containing doped working medium block 1 continuously undergoes phase change and decomposition and enters the interior of the capillary channel 12, increasing the internal pressure of the cavity, so that the plasma continuously moves towards the cathode nozzle 6 under the action of the pressure gradient and finally ejects outward to generate a high-temperature and high-density plasma jet 13; the voltage-current waveform of a single capillary discharge is as Figure 11 shown. When the charging voltage of the energy storage capacitor C1 is 2000 V and the stored energy is 280 J, the voltage-current waveform of a single discharge is as Figure 11 shown. The peak value of the discharge current is about 7.4 kA. From the breakdown of the trigger gap 15, the delay of the plasma jet trigger process is about 74 μs, and the whole discharge process is about 130 μs.

[0086] It should be noted that after multiple discharges, the anode 2 and the trigger electrode 3 are ablated by the arc, and their lengths are continuously shortened. As a result, the length of the trigger gap 15 between the end of the anode 2 and the end of the trigger electrode 3 gradually becomes longer, and the required breakdown voltage gradually increases. If the breakdown voltage required for the trigger gap 15 is higher than the output voltage of the pulse voltage generation circuit 9, the jet device cannot trigger the capillary discharge plasma jet and thus cannot work. For a greater number of discharge times in the burst mode, the phenomenon of electrode ablation and shortening is particularly obvious. In this device, the no-load output voltage of the pulse voltage generation circuit 9 is increased to 39 kV, and the creepage distance is increased by designing a structure in which the energetic doped working fluid block 1 and the insulator 4 are engaged with each other, and the creepage distance along the outer surface of the insulator 4 is increased to prevent flashover discharge from occurring at other positions except the trigger gap 15, resulting in trigger failure.

[0087] This capillary discharge plasma jet device triggers and conducts the long capillary channel 12 between the anode 2 and the cathode front flange cover 5 through plasma jet injection. The ablation mass of the working fluid block and the electrode during a single discharge is in the range of several milligrams to dozens of milligrams, and there is no obvious change in their morphology after a single discharge.

[0088] 3) After the trigger signal 20 is sent for 580 μs, the control charging start signal 23 is sent to the LC series resonance charging power supply (17) to control it to start charging the energy storage capacitor C1 again, starting the next burst discharge cycle, and so on until the preset number of discharges is reached, and the ignition system stops working. The system can repeatedly generate plasma jets at a maximum frequency of 20 Hz. The voltage of the energy storage capacitor C1 and the waveform of the arc discharge current in the capillary channel during the burst charge and discharge process are as Figure 13 shown.

[0089] When applied to engine ignition, the specific steps are as follows:

[0090] Step 1: In Figure 1 , before ignition, the adiabatic baffle 30 is opened so that the plasma jet can enter the engine combustion chamber 29.

[0091] Step 2: The LC series resonance charging circuit 17 quickly charges the energy storage capacitor C1 to a predetermined voltage.

[0092] Step 3: The pulse current generation circuit 10 operates to generate a pulsed high current, and the pulsed high current ablates the energetic doped capillary working fluid block 1 in the capillary jet device 19 to generate a high-density, high-temperature, and highly active plasma jet 13.

[0093] Step 4: The plasma jet 13 is ejected and acts on the propellant, which can be in the form of gas, liquid, or solid. To improve the ignition efficiency, the energy storage capacitor C1 needs to be repeatedly charged, and the pulsed plasma jet 13 can be repeatedly generated at a maximum frequency of 20 Hz.

[0094] Step 5: Under the cumulative action of the thermal effect and chemical effect of the pulsed thermal plasma jet, the propellant burns after reaching the ignition point, achieving successful ignition of the propulsion system;

[0095] Step 6: As Figure 3 shown, the control system controls the closing of the adiabatic partition 30 to protect the ignition system from erosion by the high-temperature gas inside the engine;

[0096] Step 7: When reignition is required after the engine shuts down, open the adiabatic partition 30 and repeat the above steps to achieve the next ignition. The ignition moment in this process can be flexibly adjusted.

[0097] The ignition system of the present invention uses an energetic-doped high polymer as the working medium of the capillary jet device, and utilizes the chemical reaction between the active metal component and the polytetrafluoroethylene component in the plasma during discharge to release energy and enhance the single-jet energy; at the same time, an LC series resonant charging circuit is used to quickly charge and discharge the energy storage system to generate a repetitive capillary discharge plasma jet at a maximum frequency of 20 Hz, and two means of using the thermal accumulation effect are used to improve the ignition efficiency of the device. Compared with the existing repetitive capillary discharge jet device, the present invention simplifies the circuit topology, which is beneficial to the miniaturization of the device; the jet device increases the trigger electrode voltage and enhances the creepage length of the insulator, adapts to the shortening of the ablation length of the electrode and the increase of the breakdown voltage of the trigger gap, realizes more discharge times, prolongs the service life of the jet device, and makes it more suitable for the repetitive discharge condition with a large number of discharge times. Using all-solid working medium, there is no need for an ignition material storage and supply device and mechanism, the system is simple and reliable, and an all-hardware drive controller is used to avoid the possibility of system failure in extreme environments. By using two means, namely, releasing chemical energy by the energetic-doped working medium to enhance the single plasma jet energy and the heat accumulation effect of the repetitive plasma jet, to improve the ignition efficiency of the plasma jet, the present invention can achieve multiple ignitions of the engine and flexible control of the ignition moment, and improve the intelligent level of the engine.

Claims

1. A heavy frequency plasma jet ignition system using an energetic modified working fluid, characterized in that: It comprises a capillary jet device (19), a pulse voltage generating circuit (9), a pulse current generating circuit (10), a thyristor trigger circuit (16), an LC series resonant charging circuit (17) and a control system (18); The capillary jet device (19) uses an energy-enhancing modified working medium and can be operated repeatedly. The capillary jet device (19) comprises an energetic doping working medium block (1), which is coaxially mounted inside a housing (8). The energetic doping working medium block (1) is made of active metal powders ranging from nanometers to micrometers, mixed with polymer powders, pressed, sintered, and machined to form a modified energetic working medium. A capillary channel (12) is machined on the axis, and a cylindrical channel (14) is machined on the side to communicate with the capillary channel (12). The front of the housing (8) is connected to a front flange cover plate (5), and the rear is connected to a rear flange cover plate (7). The front flange cover plate (5) is coaxially machined to form an expansion-type cathode nozzle. (6); the anode (2) is inserted into the capillary channel (12) from the rear of the energetic doping working medium block (1), and the trigger electrode (3) is inserted from the cylindrical channel (14) on the side of the energetic doping working medium block (1), so that the capillary channel (12) between the end of the anode (2) and the front flange cover (5) is divided into a part between the anode (2) and the trigger electrode (3), which is called a trigger gap (15), and two parts between the trigger electrode (3) and the front flange cover (5); insulators (4) are installed outside the anode (2) and the trigger electrode (3) to achieve electrical isolation from the housing, and a limit screw (11) is installed on the outside of the insulator (4) and fixedly connected to the housing (8); The connection relationship of each module in the heavy-frequency plasma jet ignition system is as follows: the high voltage output end of the pulse voltage generating circuit (9) is connected to the trigger electrode (3) of the capillary jet device (19), and the low level output end is connected to the front flange cover (5) of the capillary jet device (19); the high voltage output end of the pulse current generating circuit (10) is connected to the anode (2) of the capillary jet device (19), and the low voltage output end is connected to the front flange cover (5) of the capillary jet device (19), and the front flange cover (5) of the capillary jet device (19) is grounded through a grounding wire; the high voltage output end of the LC series resonant charging circuit (17) is connected to the high voltage end of the energy storage capacitor C1 in the pulse current generating circuit (10); The low voltage output end is connected to the low voltage end of the energy storage capacitor C1 in the pulse current generating circuit (10) to realize the rapid charging of the energy storage capacitor C1; the two driving voltage output ends of the thyristor triggering circuit (16) are respectively connected to the thyristor SCR2 in the pulse voltage generating circuit (9) and the thyristor SCR1 in the pulse current generating circuit (10) to turn on the two thyristors; the control system (18) connects the LC series resonant charging circuit (17) and the thyristor triggering circuit (16) through an optical fiber, and sends a charging start signal (23) to the LC series resonant charging circuit (17) and sends a trigger thyristor control turn-on signal (20) to the thyristor triggering circuit (16) according to a set frequency; When applied to the ignition of a propulsion system, a capillary jet device (19) in a heavy-frequency pulse plasma jet ignition system is connected to the end of a housing (27) of an engine (31), a propellant (28) is placed inside the engine combustion chamber (29), and an insulating baffle (30) is installed between the cathode nozzle (6) of the capillary jet device (19) and the combustion chamber (29) of the engine (31). The baffle is opened when the engine needs to be ignited and closed after the engine is ignited, so as to isolate the capillary jet device (19) from the influence of the high-temperature and high-pressure combustion gas in the combustion chamber (29).

2. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 1, characterized in that: In the pulse voltage generating circuit (9), the high voltage end of the DC power supply U1 is connected to the charging current limiting resistor R C2 One end, charging current limiting resistor R C2 The other end is divided into two paths, one path is connected to one end of the trigger capacitor C2 as the high voltage end of the trigger capacitor C2, and the other path is connected to the anode of the thyristor SCR2; the other end of the trigger capacitor C2, that is, the low voltage end, is divided into two paths, one path is connected to the low voltage end of the DC power supply U1, and the other path is connected to one end of the primary coil of the pulse transformer T1; the cathode of the thyristor SCR2 is connected to the other end of the primary coil of the pulse transformer T1; the anti-parallel diode VT2 is connected in parallel with the primary coil of the pulse transformer T1, its anode is connected to the low voltage side of the trigger capacitor C2, and its cathode is connected to the cathode of the thyristor SCR2; the first trigger signal (21) of the thyristor trigger circuit (16) controls the gate level of the thyristor SCR2 to open, so as to control the trigger capacitor C2 Discharge to the primary side of the pulse transformer T1; the high-voltage output end of the secondary side of the pulse transformer T1 is connected to one end of the DC blocking capacitor C3, the other end of the DC blocking capacitor C3 is divided into two paths, one path is connected to one end of the saturable inductor L, and the other path is led out as the high-voltage output end of the pulse voltage of the pulse voltage generating circuit (9), and connected to the trigger electrode (3) of the capillary jet device (19); the other end of the wave modulation inductor L is connected to one end of the trigger loop current limiting resistor R, the other end of the trigger loop current limiting resistor R is divided into two paths, one path is connected to the low-voltage output end of the secondary side of the pulse transformer T1, and the other path is led out as the low-voltage output end of the pulse voltage of the pulse voltage generating circuit (9), and connected to the front flange cover (5) of the capillary jet device (19).

3. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 2, characterized in that: The turns ratio of the primary and secondary coils of the pulse transformer T1 is 1:

39.

4. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 1, characterized in that: In the pulse current generating circuit (10), the high and low voltage ends of the energy storage capacitor C1 are respectively connected to the high and low voltage output ends of the LC series resonant charging circuit (17), and the energy storage capacitor C1 is quickly charged to a preset voltage before a single discharge begins; the high voltage end of the energy storage capacitor C1 is connected to the anode of the thyristor SCR1, and the thyristor SCR1 is connected in anti-parallel to the diode VT1, wherein the anode of the thyristor SCR1 is connected to the cathode of the diode VT1, and the cathode of the thyristor SCR1 is connected to the anode of the diode VT1. The cathode end of the thyristor SCR1 is led out as the high-voltage output end of the pulse current generating circuit (10) and connected to the anode (2) of the capillary jet device (19); the thyristor trigger circuit (16) sends a second trigger signal (22) to the gate of the thyristor SCR1 to control the thyristor SCR1 to turn on and control the energy storage capacitor C1 to discharge; the low-voltage side of the energy storage capacitor C1 is led out as the low-voltage output end of the pulse current generating circuit (10) and connected to the front flange cover (5) of the capillary jet device (19).

5. The heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 1, characterized in that: In the LC series resonant charging circuit (17), the primary side of the transformer T: the first IGBT module S1, the second IGBT module S2, the third IGBT module S3 and the fourth IGBT module S4 of the N-channel IGBT module are connected in a bridge manner, wherein each IGBT module S i Both with diode D i Anti-parallel connection, IGBT module S i Collector and diode D i Cathode connection, IGBT module S i Emitter and diode D i anode connection, i=1, 2, 3, 4; the high voltage end of the DC power supply U2 is connected to the collectors of the first IGBT module S1 and the third IGBT module S3, the emitter of the first IGBT module S1 is connected to the collector of the second IGBT module S2, the emitter of the third IGBT module S3 is connected to the collector of the fourth IGBT module S4, the emitters of the third IGBT module S3 and the fourth IGBT module S4 are connected and connected to the low voltage side of the DC power supply U2; the gates of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3 and the fourth IGBT module S4 are respectively connected to the full hardware drive controller (24), and the full hardware drive controller (24) sends control signals to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3 and the fourth IGBT module S4 to control their opening and closing; the emitter of the first IGBT module S1 is connected to the resonant inductor L r One end, resonant inductor L r The other end is connected to the resonant capacitor C r One end, resonant capacitor C r The other end is connected to one end of the primary coil of the transformer T, and the other end of the primary coil of the transformer T is connected to the emitter of the third IGBT module S3; the secondary side of the transformer T is connected to a diode full-bridge rectifier circuit composed of a first diode D5, a second diode D6, a third diode D7 and a fourth diode D8, the anode of the first diode D5 is connected to the cathode of the second diode D6, the anode of the third diode D7 is connected to the cathode of the fourth diode D8, one end of the secondary side of the transformer T is connected to the anode of the first diode D5 and the cathode of the second diode D6, the other end of the secondary side of the transformer T is connected to the anode of the third diode D7 and the cathode of the fourth diode D8, the cathode of the first diode D5 and the cathode of the third diode D7 are connected and connected to one end of the filter inductor L2, the other end of the filter inductor L2 is connected to the collector of the fifth IGBT module S5, the emitter of the fifth IGBT module S5 is connected to the high-voltage output end of the LC series resonant charging circuit, and the gate of the fifth IGBT module S5 is connected to a full hardware drive controller (24), which is controlled by the full hardware drive controller (24). The fifth IGBT module S5 is turned on and off to control the on and off of the output circuit; the negative polarity output end of the diode full-bridge rectifier circuit is connected to the low voltage output end of the LC series resonant charging circuit module; a resistor voltage divider (26) composed of a first resistor R1 and a second resistor R2 is connected in parallel between the high and low voltage output ends of the LC series resonant charging circuit; one end of the first resistor R1 is connected to the high voltage output end, and the other end is connected to one end of the second resistor R2; the other end of the second resistor R2 is connected to the low voltage output end, and is connected to the anodes of the second diode D6 and the fourth diode D8; the voltage signal divided by the resistor voltage divider (26) is input into the photoelectric isolation module (25), and is input into the full hardware drive controller (24) after signal isolation; at the same time, the control signal from the control system (18) controls the operation of the full hardware drive controller (24), controls the start and stop of the PWM signal driving the bridge arms of the first IGBT module S1, the second IGBT module S2, the third IGBT module S3 and the fourth IGBT module S4, and controls the on and off of the fifth IGBT module S5.

6. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 5, characterized in that: The resistance of the first resistor R1 is 1334 times the resistance of the second resistor R2.

7. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 1, characterized in that: The preparation method of the energetic doping working medium block (1) is as follows: Active metal powders of nanometer to micrometer size and polymer powders of micrometer particle size are mixed in a certain proportion, with active metal powder accounting for 3%-26% of the total mass of the powders, or part of active metal oxide powders are doped to improve the mechanical properties of the energetic working medium block, or a small amount of ammonium perchlorate powder is added to increase the chemical energy released by the reaction; all the powders are placed in a mixer for shearing and mixing, and then placed in a cylindrical hydraulic press mold with a hole in the middle, the filling is completed at one time, pressurized and maintained, and then the hydraulic press pressure is gradually released to form a cylindrical hair with a through hole in the middle. The blank is left to stand to eliminate internal stress, and then sintered in an argon protective atmosphere, firstly heating the temperature to 370-390 degrees Celsius at a heating rate of 50 degrees Celsius per hour, keeping the temperature for 2-6 hours, then cooling the temperature to 327 degrees Celsius at a cooling rate of 50 degrees Celsius per minute, keeping the temperature for 2 hours, and then cooling the temperature to room temperature at a cooling rate of 50 degrees Celsius per minute; finally, through mechanical processing, the axial position of the working fluid block is processed into a capillary channel (12), and a cylindrical channel (14) is vertically processed inwardly on the side of the cylindrical working fluid block to communicate with the capillary channel (12).

8. A heavy frequency plasma jet ignition system using an energetic modified working medium according to claim 7, characterized in that: The active metal powder is aluminum powder or boron powder; the polymer powder is polytetrafluoroethylene, high-density polyethylene or polyetheretherketone.

9. The heavy-frequency plasma jet ignition system using an energetic modified working medium according to claim 1, characterized in that: The no-load output voltage of the pulse voltage generating circuit (9) is 39 kV, so that when the breakdown voltage required for the trigger gap (15) is higher than the output voltage of the pulse voltage generating circuit (9), the plasma jet ignition device cannot be triggered to cause a capillary discharge plasma jet and thus cannot work; The energetic doping working medium block (1) and the insulator (4) are provided with a structure in which the insulator (4) first gradually expands and then interlocks with each other in equal diameters within the energetic doping working medium block (1) to increase the surface distance, increase the outer surface distance of the insulator (4), and prevent flashover discharge from occurring at positions other than the trigger gap (15) and causing trigger failure.

10. The working method of the heavy frequency plasma jet ignition system using the energetic modified working medium according to any one of claims 1 to 9, characterized in that: Plasma jets are repeatedly generated at a set frequency. In each cycle, the control system (18) controls the DC power supply U2 in the LC series resonant charging circuit to start charging by sending a charging start signal (23) to a full hardware drive controller (24) in the LC series resonant charging circuit (17). The control system (18) inputs an opening signal (20) to the thyristor trigger circuit (16) at a set frequency to trigger a single capillary discharge to induce a plasma jet. Each cycle of generating a plasma jet is divided into two steps: charging the energy storage system and generating a plasma jet by pulse discharge. 1) Energy storage system charging process: the control system (18) sends a charging start signal (23) to the full hardware drive controller (24) in the LC series resonant charging circuit (17), and the LC series resonant charging circuit (17) starts to work; the full hardware drive controller (24) inputs complementary PWM drive signals with a duty cycle of 25% to the first IGBT module S1 and the third IGBT module S3 as a group, and the second IGBT module S2 and the fourth IGBT module S4 as a group, to control the bridge arm interval opening; the DC power provided by the DC power supply U2 is converted into AC power, which is boosted by the transformer T and converted into DC power again by the diode full bridge rectifier circuit, so as to realize charging the energy storage capacitor C1 to a maximum of 2000 V high voltage; a resistor voltage divider (26) connected to the output end collects the voltage of the energy storage capacitor C1, divides the 0-2000V voltage of the energy storage capacitor C1 into a voltage signal of 0-1.5V, and inputs the voltage into the full hardware drive controller (24) through the photoelectric isolation module (25), compares the voltage with the set charging voltage through the operational amplifier circuit, and determines whether the voltage of the energy storage capacitor C1 reaches the preset voltage through the gate circuit group. When the voltage of the energy storage capacitor C1 reaches the set charging voltage, the full hardware drive controller stops inputting the driving PWM signal to the first IGBT module S1, the second IGBT module S2, the third IGBT module S3 and the fourth IGBT module S4, and controls the fifth IGBT module S5 to turn off the charging circuit; 2) Pulse discharge generates plasma jet process: when the trigger discharge moment is reached, the control system (18) transmits a trigger plasma jet signal to the thyristor trigger circuit (16); the thyristor trigger circuit (16) transmits a second trigger signal (22) to the thyristor SCR1 in the pulse current generating circuit (10), controls the thyristor SCR1 to be turned on, applies the voltage of the energy storage capacitor C1 between the anode (2) and the front flange cover plate (5), and the front flange cover plate (5) serves as a cathode during the discharge process; after a delay, the thyristor trigger circuit (16) inputs a first trigger signal (21) to the thyristor SCR2 in the pulse voltage generating circuit, controls the thyristor SCR2 to be turned on, applies a trigger high voltage pulse to the trigger electrode (3), and induces surface discharge in the trigger channel (15) between the end of the anode (2) and the end of the trigger electrode (3); The trigger channel (15) discharges along the surface to form an arc, and the high-conductivity plasma formed by ablating the capillary wall material of the trigger channel (15) moves toward the front flange cover plate (5) serving as the cathode. When the plasma reaches the cathode front flange cover plate (5), the capillary channel between the anode (2) and the cathode front flange cover plate (5) is filled with the high-conductivity plasma, and the channel between the anode (2) and the cathode front flange cover plate (5), that is, the high voltage output terminal and the low voltage output terminal of the pulse current generating circuit (10) are short-circuited, and the high voltage output terminal of the pulse current generating circuit (10) is connected to the low voltage output terminal. ——Anode (2)——Arc in the capillary channel (12)——Cathode front flange cover (5)——A discharge loop at the low voltage output end of the pulse current generating circuit (10) is formed, and the electric energy stored in the energy storage capacitor in the pulse current generating circuit (10) begins to be released through the arc load in the capillary channel (12). The high-temperature arc radiation energy causes the energetic doping material of the capillary wall of the solid working fluid to ablate to form a high-temperature and high-pressure plasma, and the active metal powder and polymer powder components in the plasma undergo a chemical reaction to release energy, further increasing the internal energy of the plasma jet. The inner wall material of the capillary channel (12) of the energetic doping working fluid block (1) continuously changes phase and decomposes into the interior of the capillary channel (12), increasing the internal pressure of the cavity, so that the plasma continuously moves toward the cathode nozzle (6) under the action of the pressure gradient, and finally ejects outward to generate a high-temperature and high-density plasma jet (13); The heavy-frequency plasma jet ignition system triggers the capillary channel (12) between the anode (2) and the front flange cover plate (5) through plasma jetting. The mass of the working fluid block and the electrode ablation in a single discharge is between several milligrams and tens of milligrams. There is no obvious change in the morphology after a single discharge. The next discharge starts immediately after the pulse current generating circuit (10) completes energy storage. The above process is repeated to repeatedly draw out the plasma jet at a set frequency until the propellant (28) is ignited, and the heat insulation baffle (30) is closed. When the next ignition time arrives, the heat insulation baffle (30) is opened and the above process is repeated to achieve repeated ignition of the engine.

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