Ultrasonic-assisted magnetic control plasma polishing method and device for hard and brittle elements

Abstract

The invention belongs to the technical field of hard and brittle optical element machining, and particularly relates to an ultrasonic-assisted magnetic control plasma polishing method and device for hard and brittle elements, and the method comprises the steps that working gas and compressed oxygen are mixed and conveyed to a plasma guide pipe in a stable pressure mode; gas is ionized through a high-voltage tungsten needle electrode, plasma jet is generated, and discharge parameters are adjusted; an annular ultrasonic array is used for forming a high-intensity ultrasonic field, electric arc divergence is restrained, and jet flow focusing is orderly; jet flow is guided to enter a conical rotating magnetic field area, and the energy concentration ratio is improved through secondary focusing and acceleration of a rotating magnetic field; and the jet flow acts on the surface of the optical element to realize physical etching or chemical reaction. The plasma is restrained through the rotating magnetic field, the movement track is accurately controlled, the machining precision is improved, and the problems of arc instability, low machining efficiency, high surface roughness, subsurface damage and poor material adaptability in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of processing hard and brittle optical elements that are difficult to process. Specifically, it relates to a method and device for ultrasonic-assisted magnetron plasma polishing of hard and brittle elements. Background Art

[0002] In modern optical systems, optical elements, as core components, play a crucial role in aerospace, national defense, and high-end civilian fields (such as satellite observation, laser weapons, lithography machines, etc.). The processing accuracy of these elements directly determines the imaging quality and stability of the optical system. However, optical materials (such as quartz, sapphire, etc.) usually have high hardness and brittleness, and traditional processing methods are difficult to meet the requirements of ultra-precision processing, easily leading to surface cracks and subsurface damage, thereby affecting the performance of optical elements.

[0003] Currently, the processing methods of optical elements mainly include mechanical processing, chemical etching, and laser processing, etc. Among them, mechanical processing (such as grinding, polishing) can improve the processing accuracy to a certain extent, but it is easy to generate micro-cracks and surface damage for hard and brittle materials, and at the same time, the processing efficiency is relatively low; although the chemical etching method can perform large-area uniform removal, its processing accuracy is relatively low, and the surface quality is difficult to strictly control; laser processing has a high energy density and good processing accuracy, but it is easy to cause thermal damage and material melting during the processing of hard and brittle materials, affecting the final surface quality. The limitations of these traditional processing methods make the precision manufacturing of optical elements face great challenges and limit the further improvement of processing accuracy and quality.

[0004] In recent years, plasma jet processing technology, as a new optical element processing method, has shown unique advantages. The plasma jet has high temperature, high energy density, and good directivity, and can achieve efficient etching and surface modification of optical materials. During the processing, the active particles in the plasma jet interact physically and chemically with the surface of the optical material, thereby removing the material and regulating the surface morphology. Compared with traditional processing methods, plasma jet processing has higher processing accuracy, better surface quality, and can also achieve the processing of complex shapes, so it has broad application prospects in the field of ultra-precision optical element manufacturing.

[0005] However, there are still some key technical problems in the current plasma jet machining technology that need to be solved urgently. Among them, the focusing and acceleration of the plasma jet are important factors affecting the ultra-precision machining effect. Traditional plasma jets usually exhibit the characteristics of divergence and disorder, resulting in a low energy density and it is difficult to further improve the machining accuracy. For this reason, researchers have proposed a series of methods for plasma jet focusing and acceleration, such as electromagnetic field constraint, gas dynamics regulation, and optical constraint technologies. However, these methods still have certain limitations in practical applications. For example, the accuracy of electromagnetic field constraint is difficult to meet the requirements of ultra-precision machining, gas dynamics regulation is likely to introduce additional fluid interference, and optical constraint technology has problems such as energy loss and damage to optical components.

[0006] Therefore, in view of the ultra-precision machining requirements of hard and brittle optical components, it is urgent to develop a new type of plasma processing method with high efficiency and low damage to further improve the machining quality and accuracy and meet the needs of high-end optical manufacturing. Summary of the Invention

[0007] In view of the above problems, the present invention provides a method and device for ultrasonic-assisted magnetron plasma polishing of hard and brittle components, which solves the problems of arc instability caused by factors such as air flow and pressure fluctuation in the prior art, low machining efficiency, high surface roughness and subsurface damage of the optical component material surface, and poor adaptability to different materials. Through the effective constraint of the plasma by the rotating magnetic field, the Lorentz force is used to precisely control the movement trajectory of the plasma, reduce the jet beam width, improve the energy concentration, and make the machining process more efficient and accurate.

[0008] On the one hand, the present invention provides a method for ultrasonic-assisted magnetron plasma polishing of hard and brittle components, and the method includes:

[0009] Step 1: Mix the working gas and compressed oxygen in a preset ratio, and adjust the pressure through a gas pressure reduction mixer to make the mixed gas stably flow into the inner cavity of the plasma conduit;

[0010] Step 2: Ionize the mixed gas by a high-voltage tungsten needle electrode under the action of high-frequency and high-voltage to generate a plasma jet, and adjust the discharge parameters through a frequency conversion matching controller;

[0011] Step 3: Make the plasma jet pass through an annular ultrasonic array, and form a high-intensity ultrasonic field under the drive of an annular ultrasonic array controller. Use the ultrasonic field to suppress the divergent and disordered state of the arc, make it transform into a concentrated and ordered state, and regulate the movement trajectory of the plasma to pre-focus the plasma jet;

[0012] Step 4: Guide the plasma jet pre-focused by the ultrasonic field into the conical rotating magnetic field region. Use the conical rotating magnetic field generating device to generate a conical rotating magnetic field under the action of the conical coil iron core, and perform secondary focusing and acceleration on the pre-focused plasma jet.

[0013] Step 5: Act the plasma jet beam after magnetic secondary focusing and acceleration on the surface of the optical element to be processed, and perform physical etching or chemical reaction through the high-energy active particles in the plasma with the surface of the optical element material.

[0014] In a preferred implementation, further, in Step 3, the formation process of the ultrasonic field includes: the ultrasonic transducer array is arranged in a ring shape. When the ultrasonic transducer receives the high-frequency electrical signal sent by the drive power supply, it quickly converts electrical energy into mechanical vibration to generate high-frequency ultrasonic waves. The ultrasonic waves propagate in the air medium, forming alternating compression waves and rarefaction waves, and generating a highly focused sound field structure in the plasma jet region.

[0015] In a preferred implementation, further, in Step 3, by adjusting the drive frequency and power of the ultrasonic transducer, the intensity and distribution of the ultrasonic field can be dynamically controlled, thereby optimizing the focusing degree and energy density of the plasma jet.

[0016] In a preferred implementation, further, the secondary focusing and acceleration process of the conical rotating magnetic field includes: the magnetic force generated by the rotating magnetic field in its action region further focuses the already pre-focused plasma jet, reduces the divergence degree of the jet, improves the density and energy concentration of the jet, and the rotating magnetic field makes the charged particles in the plasma move in a spiral trajectory under the action of the magnetic force, increasing their speed and kinetic energy in the jet.

[0017] In a preferred implementation, further, in Step 5, physical etching is through the impact and stripping action of high-energy ions on the material surface; chemical reaction is through the reaction of reactive gases or free radicals in the plasma with the material to chemically react and convert part of the surface layer of the material into volatile substances or oxidation products.

[0018] In a preferred implementation, further, in Step 5, physical etching is suitable for the removal of hard optical materials, and chemical reaction is suitable for the fine regulation and cleaning of the material surface.

[0019] In a preferred implementation, further, in Step 1, the working gas includes but is not limited to one or more of argon, carbon tetrafluoride, and sulfur hexafluoride.

[0020] On the other hand, the present invention also provides an ultrasonic coupling electromagnetic controlled plasma hard and brittle element processing device, which is used to implement the ultrasonic assisted magnetron plasma polishing method for hard and brittle elements described in any one of the above; the device includes a plasma duct, a plasma generating component, an ultrasonic focusing component, and a conical rotating magnetic field generating component, wherein:

[0021] The plasma duct has an inner cavity, and a mixed gas inlet for compressed oxygen and working gas is provided at the top thereof, and an air outlet is provided at the bottom. An optical element material to be processed is placed below the air outlet, and the air outlet is used to act the high-energy focused jet beam on the surface of the optical element material to be processed;

[0022] The plasma generating component includes a high-voltage tungsten needle electrode, and the high-voltage tungsten needle electrode is arranged at the top of the inner cavity of the plasma duct; the high-voltage tungsten needle electrode is used for discharging and ionizing the mixed gas to form a plasma jet;

[0023] The ultrasonic focusing component includes an annular ultrasonic array located below the high-voltage tungsten needle electrode. The annular ultrasonic array is composed of a plurality of ultrasonic emission units, and each ultrasonic emission unit is evenly distributed and embedded in the inner cavity wall surface of the plasma duct; the annular ultrasonic array is used to generate an ultrasonic sound field and pre-focus the plasma jet;

[0024] The conical rotating magnetic field generating component includes a conical coil and a conical coil iron core. The conical coil iron core is arranged in the inner cavity of the plasma duct and is located below the annular ultrasonic array. Its conical opening faces downward and is communicated with the air outlet of the plasma duct. A plurality of conical coils are evenly arranged around the surface of the conical coil iron core; the conical coil is used to generate a conical rotating magnetic field when the focused plasma jet passes through, so that the plasma jet performs a spiral contraction movement along the magnetic induction line trajectory, obtains kinetic energy gain, and thus forms a high-energy focused jet beam.

[0025] In a preferred implementation manner, further, the plasma generating component further includes a gas pressure reducing mixer and a frequency conversion matching controller. The electrode tail of the high-voltage tungsten needle electrode is connected to the frequency conversion matching controller, and the gas pressure reducing mixer is connected to the air inlet of the plasma duct through a pipeline;

[0026] The conical rotating magnetic field generating component further includes an insulating sheet, and the insulating sheet is installed outside each conical coil and covers the entire area of the conical coil.

[0027] In a preferred implementation, further, the plasma catheter is composed of a straight tube structure in the upper part and a conical tube structure in the lower part. The two are connected to each other and internally communicate to jointly form the inner cavity of the plasma catheter. The straight tube structure is located in the upper part of the plasma catheter, and an air inlet is provided at its top. The conical tube structure in the lower part is tapered and contracted, with the taper angle facing downwards, and an air outlet is provided at its bottom end. The outer surface of the conical coil iron core matches the inner surface of the conical tube structure of the plasma catheter.

[0028] The beneficial effects of the present invention are as follows:

[0029] First, in the ultrasonic-assisted magnetron plasma polishing method for brittle elements of the present invention, through the synergistic effect of the ultrasonic field and the conical rotating magnetic field, multi-stage focusing and precise trajectory control of the plasma jet are achieved, improving the stability and precision of processing. The pre-focusing effect of the ultrasonic field effectively suppresses the divergence of the arc, causing the plasma jet to change from disorder to order, ensuring the concentrated utilization of plasma energy, and reducing the problem of reduced processing accuracy caused by energy dispersion in traditional plasma jets. The secondary focusing and acceleration of the conical rotating magnetic field further enhance the energy density and directivity of the jet, increasing the material removal rate and effectively reducing the thermal affected area during processing, reducing the risk of material damage. Compared with traditional methods such as mechanical processing, chemical etching, and laser processing, this method can effectively reduce the thermal affected area during processing, reduce material damage, and is particularly suitable for the fine processing of high-precision optical elements, meeting the processing requirements for complex morphologies and high surface quality in the high-end manufacturing field.

[0030] Second, in a preferred implementation, step 3 of the present invention forms a highly focused sound field structure in the plasma jet region through the high-frequency mechanical vibration of the annular ultrasonic transducer array, achieving precise control of the plasma. The alternating action of the compression wave and rarefaction wave of the ultrasonic wave effectively suppresses the divergence of the plasma jet, improving its stability and energy concentration. At the same time, by adjusting the driving frequency and power of the ultrasonic transducer, the intensity and distribution of the ultrasonic field can be dynamically optimized, thereby precisely controlling the focusing degree and energy density of the plasma jet, improving the processing uniformity and efficiency, reducing material damage, and meeting the requirements for processing high-precision brittle elements.

[0031] Third, in a preferred implementation, the method of the present invention performs secondary focusing and acceleration on the pre-focused plasma jet through the conical rotating magnetic field, effectively reducing the divergence of the jet, and increasing its density and energy concentration. Under the action of the rotating magnetic field, the charged particles in the plasma move along a helical trajectory, further enhancing their velocity and kinetic energy in the jet, thereby improving the material etching efficiency and processing accuracy.

[0032] Fourth, in the preferred implementation, the method of the present invention combines two processing mechanisms of physical etching and chemical reaction, enabling the plasma jet to adapt to the processing requirements of different types of optical materials. The impact and stripping effects of high-energy ions can efficiently remove hard optical materials, increasing the material removal rate, while the reactive gases or free radicals in the plasma can chemically react with the materials to achieve fine regulation and cleaning of the material surface layer, improving the surface quality.

[0033] Fifth, the ultrasonic-coupled electromagnetic-controlled plasma brittle element processing device provided by the present invention realizes precise control and efficient focusing of the high-energy plasma jet through multi-stage regulation of plasma generation, ultrasonic focusing, and conical rotating magnetic field. The plasma duct ensures the stable supply and jet guidance of the mixed gas, and the high-voltage tungsten needle electrode realizes efficient ionization and forms a stable plasma jet. The annular ultrasonic array regulates the movement trajectory of the plasma through the high-frequency sound field, inhibits jet divergence, and improves the energy concentration of the jet. The conical rotating magnetic field further performs spiral contraction acceleration on the jet, significantly increasing its energy density and enhancing the etching and fine processing capabilities for the optical element materials.

[0034] Sixth, in the preferred implementation, the device of the present invention realizes stable regulation of the mixed gas supply and precise control of the plasma discharge parameters by adding a gas pressure reduction mixer and a frequency conversion matching controller in the plasma generation component, ensuring the stability and uniformity of the plasma jet. At the same time, an insulating sheet is introduced in the conical rotating magnetic field generation component to effectively isolate the conical coil, prevent electromagnetic interference, improve the magnetic field control accuracy, and enhance the safety of the device operation.

[0035] Seventh, in the preferred implementation, the device of the present invention adopts a plasma duct design that combines an upper straight cylinder structure and a lower conical cylinder structure, enabling the plasma jet to be stably formed in the straight cylinder structure first and then restricted and contracted in the conical cylinder structure when passing through the duct, improving the directivity and energy density of the jet. The contraction effect of the conical cylinder structure enhances the focusing effect of the air flow and the plasma, further reducing jet divergence and improving the processing accuracy. At the same time, the outer surface of the conical coil iron core matches the inner surface of the conical cylinder structure, enabling the conical rotating magnetic field to act more efficiently on the plasma jet, achieving better spiral contraction acceleration, improving the plasma energy transfer efficiency, and ultimately enhancing the processing quality and efficiency of the optical element. Description of the Drawings

[0036] Figure 1 is a flowchart of the ultrasonic-assisted magnetron plasma polishing method for brittle elements in an embodiment of the present invention;

[0037] Figure 2 is an effect diagram of processing optical element materials by a method that does not combine ultrasonic focusing and conical rotating magnetic field in the prior art;

[0038] Figure 3 It is the effect diagram of processing the optical element material by the ultrasonic-assisted magnetron plasma polishing method of brittle elements in the embodiments of the present invention;

[0039] Figure 4 It is the structural schematic diagram of the ultrasonic-coupled electromagnetic-controlled plasma brittle element processing device in the embodiments of the present invention;

[0040] Figure 5 It is the structural schematic diagram of the conical rotating magnetic field of the ultrasonic-coupled electromagnetic-controlled plasma brittle element processing device in the embodiments of the present invention;

[0041] Figure 6 It is the structural schematic diagram of the ultrasonic emission unit of the ultrasonic-coupled electromagnetic-controlled plasma brittle element processing device in the embodiments of the present invention;

[0042] Figure 7 It is the diagram of the change of high-voltage arc under the action of the ultrasonic field in the embodiments of the present invention;

[0043] Figure 8 It is the schematic diagram of the principle of the change of the plasma motion trajectory under the action of the conical rotating magnetic field in the embodiments of the present invention.

[0044] Among them, 1 - annular ultrasonic array controller, 2 - conical rotating magnetic field generating device, 3 - insulating high-voltage tungsten needle electrode base, 4 - high-voltage tungsten needle electrode fastening screw, 5 - high-voltage tungsten needle electrode, 6 - conical coil, 7 - optical element material, 8 - mixed gas inlet, 9 - annular ultrasonic array, 10 - plasma duct nozzle, 11 - workbench, 12 - gas pressure reducing mixer, 13 - frequency conversion matching controller, 14 - manual pressure reducing valve, 15 - compressed oxygen, 16 - working gas, 17 - insulating sheet, 18 - conical coil iron core, 19 - ultrasonic emission unit, 20 - high-voltage arc, 21 - ion motion trajectory, 22 - conical rotating magnetic field magnetic induction line distribution. Specific embodiments

[0045] In order to enable those skilled in the art to better understand the technical solutions of the present application, the following will further describe the present invention in detail with reference to the drawings and embodiments.

[0046] The orientation terms such as up, down, left, right, front and back in the present application document are established based on the positional relationship shown in the drawings. If the drawings are different, the corresponding positional relationship may also change accordingly, so it cannot be understood as a limitation of the protection scope.

[0047] In this application, terms such as "installation", "connection", "joining", "linkage", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection or a connection that allows mutual communication, a direct connection, an indirect connection through an intermediate medium, a connection inside two components, or an interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0048] The present invention aims to provide a method and device for ultrasonic-assisted magnetron plasma polishing of hard and brittle components. This method combines the focusing and accelerating effects of an ultrasonic field and a conical magnetic field, and can achieve non-destructive ultra-precision machining of hard and brittle materials (such as silicon carbide, calcium fluoride, fused silica, etc.). First, the acoustic force is used to stably focus the high-voltage arc, transforming the arc from a divergent and disordered state to a concentrated and ordered state. The radiation force of the high-frequency sound field greatly stabilizes the arc trajectory. Subsequently, the rotating magnetic field generated by the conical three-phase coil acts on charged particles through the Lorentz force, constraining their movement trajectories and helically accelerating the velocity of the plasma, thereby narrowing the width of the plasma beam. The plasma generated by ionizing the working gas through a high-frequency voltage undergoes physical and chemical reactions with the optical element, achieving material removal at the atomic scale. Through the synergistic effect of ultrasound and the magnetic field, the focused and accelerated plasma is significantly improved in terms of velocity, density, kinetic energy, and beam width compared to a single plasma jet, thus improving the processing efficiency and precision.

[0049] Refer to the attached Figure 1 description of the specification, the present invention describes a method for ultrasonic-assisted magnetron plasma polishing of hard and brittle components. In this method, the high-voltage arc is first stably focused by the acoustic force, transforming the arc from a divergent and disordered state to a concentrated and ordered state. The radiation force of the high-frequency sound field can greatly stabilize the arc trajectory. Then, the rotating magnetic field generated by the conical three-phase coil generates a Lorentz force on the charged particles, constraining the movement trajectories of the particles and helically accelerating the movement velocity of the plasma, thereby narrowing the width of the plasma beam. The plasma generated by ionizing the working gas through a high-frequency voltage undergoes physical and chemical reactions with the optical element, achieving material removal at the atomic scale. The specific steps are as follows:

[0050] Step 1: Mix the working gas and compressed oxygen in a preset ratio, and adjust the pressure through a gas pressure reducing mixer to make the mixed gas stably flow into the inner cavity of the plasma duct.

[0051] The purpose of Step 1 is to optimize the generation conditions of the plasma jet, ensure the stability, uniformity, and controllability of the plasma, improve the processing precision of subsequent ultrasonic focusing and magnetic field acceleration, and at the same time meet the processing requirements of different optical element materials.

[0052] Specifically, according to the material properties of the optical element to be processed, an appropriate working gas (such as argon (Ar), carbon tetrafluoride (CF4), sulfur hexafluoride (SF6), etc.) is selected and mixed with compressed oxygen (O2) in a preset ratio. For example: for quartz glass (SiO2), the working gas is argon (Ar) + oxygen (O2), and the recommended ratio is Ar:O2 = 80:20, to enhance discharge stability, improve the removal rate, and reduce surface roughness. For sapphire (Al2O3), the working gas is argon (Ar) + carbon tetrafluoride (CF4) + oxygen (O2), and the recommended ratio is Ar:CF4:O2 = 60:30:10. Argon is used to improve plasma stability, CF4 enhances chemical etching, and O2 assists in the oxidation reaction to improve surface uniformity. For calcium fluoride (CaF2), the working gas is carbon tetrafluoride (CF4) + oxygen (O2), and the recommended ratio is CF4:O2 = 70:30, to enhance chemical reaction activity, improve processing efficiency, and reduce subsurface damage at the same time. For silicon-based optical materials (Si, Si3N4, SiC), the working gas is sulfur hexafluoride (SF6) + argon (Ar) + oxygen (O2), and the recommended ratio is SF6:Ar:O2 = 50:30:20. SF6 is used to improve etching selectivity, argon increases plasma density, and O2 optimizes surface chemical stability, which is suitable for high-precision micro-structure processing.

[0053] Compressed oxygen and the working gas are respectively input from independent gas cylinders, and independent gas pressure regulators are used to adjust the inlet pressures of compressed oxygen and the working gas respectively. The pressure setting range of the working gas (Ar, CF4, SF6) is 0.1 - 0.5 MPa, and the pressure setting range of compressed oxygen (O2) is 0.05 - 0.3 MPa. After the gas enters the mixing chamber, the residence time is controlled within 0.2 - 1.0 seconds to ensure complete mixing before flowing into the plasma conduit.

[0054] Step 2: Ionize the mixed gas under the action of high-frequency high voltage through a high-voltage tungsten needle electrode to generate a plasma jet, and adjust the discharge parameters through a frequency conversion matching controller.

[0055] The purpose of Step 2 is to optimize the stability, energy density, and uniformity of the plasma jet, and provide a high-quality plasma source for subsequent ultrasonic focusing and magnetic field acceleration. The discharge parameters are precisely controlled through a frequency conversion matching controller to ensure that the plasma has appropriate electron density, temperature, and ion energy to meet the processing requirements of different optical elements. Reduce arc instability and overheating problems, prevent the material surface from melting or generating micro-cracks, and improve processing quality.

[0056] Specifically, a high-voltage tungsten needle electrode is adopted, with its tip facing the inner cavity of the plasma catheter to ensure the stable generation of plasma jets. The electrode is installed on the insulating high-voltage tungsten needle electrode base to avoid high-voltage leakage and is fixed by high-voltage tungsten needle electrode fastening screws to ensure long-term stable operation. The tungsten needle electrode can be selected as W-2% Th (2% thorium tungsten alloy), which has high heat resistance and low electron work function, improving the discharge stability.

[0057] Select a suitable discharge mode of the frequency conversion matching controller according to the processing requirements. The discharge modes include radio frequency (RF) discharge, microwave discharge, and pulsed DC discharge. RF discharge is suitable for ultra-precision low-damage processing with high plasma uniformity. Microwave discharge is suitable for high-density plasma applications to improve the etching rate. Pulsed DC discharge is suitable for controlling the heat-affected area and increasing the material removal rate.

[0058] The discharge parameters of the frequency conversion matching controller include voltage, frequency, and power. Among them, the voltage regulation range is 10 - 30 kV. The frequency regulation range: for RF discharge is 13.56 MHz, for microwave discharge is 2.45 GHz, and for pulsed DC discharge is 1 - 10 kHz. The power control range: low power (10 - 50 W) is suitable for ultra-precision surface modification, medium power (50 - 200 W) is suitable for uniform etching, and high power (200 - 500 W) is suitable for rapid material removal.

[0059] The plasma excitation process includes: The excitation of the plasma starts from the high-voltage tungsten needle electrode. After it is connected to the high-frequency high-voltage power supply (10 - 30 kV), a strong electric field is formed in the gas flow region. This electric field exerts an accelerating effect on free electrons, enabling them to obtain sufficient energy and collide with working gas molecules, triggering electron impact ionization, and thus forming a plasma (including electrons, ions, and neutral particles). To ensure the uniformity and stability of the plasma, the discharge electric field intensity is optimized to ≥10 5 V / m, effectively reducing local arc jitter, suppressing arc drift, and improving the consistency of the plasma jet.

[0060] Step 3: Pass the plasma jet through the annular ultrasonic array, and form a high-intensity ultrasonic field under the drive of the annular ultrasonic array controller. Use the ultrasonic field to suppress the divergent and disordered state of the arc, making it transform into a concentrated and ordered state, and regulate the movement trajectory of the plasma to pre-focus the plasma jet.

[0061] The purpose of Step 3 is to reduce arc drift and randomness through the action of the ultrasonic field, making the jet more directional, enhancing the uniformity of the flow field, suppressing the divergence characteristics of the plasma jet, reducing the angular diffusion of the plasma jet, making its energy more concentrated, and improving the processing accuracy. Through the focusing effect of ultrasonic waves, the plasma particles are arranged more orderly under the action of sound waves, reducing random motion and increasing the jet density. Provide a more uniform and high-density plasma input for magnetic field direction control and acceleration, improving the overall processing performance and energy utilization rate.

[0062] Specifically, an ultrasonic transducer array arranged in a ring is adopted to ensure uniform distribution of ultrasonic energy and form an axisymmetric ultrasonic field in the plasma jet region. The ultrasonic transducers are embedded in the inner wall of the plasma conduit to ensure that the jet is stably acoustically modulated when passing through the ultrasonic field.

[0063] The formation process of the ultrasonic field includes: the ultrasonic transducer array is arranged in a ring. When the ultrasonic transducers receive high-frequency electrical signals emitted by the drive power supply, they quickly convert electrical energy into mechanical vibrations, generating high-frequency ultrasonic waves. The ultrasonic waves propagate in the air medium, forming alternating compression waves and rarefaction waves, generating a highly focused sound field structure in the plasma jet region.

[0064] The ways in which the ultrasonic field acts on the plasma jet include acoustic field modulation of the arc shape, acoustic force acting on plasma particles, and ultrasonic waves guiding the jet trajectory. Acoustic field modulation of the arc shape means that the periodic pressure wave of the ultrasonic field affects the shape of the arc, causing the high-voltage discharge to change from a disordered and divergent state to a concentrated and ordered state. Acoustic force acting on plasma particles means that the vibration energy of ultrasonic waves acts on electrons, ions, and neutral particles in the plasma jet. Under the acoustic wave pressure gradient, the particle movement direction becomes more orderly, improving the uniformity and stability of the plasma jet. Ultrasonic waves guiding the jet trajectory means that the ultrasonic pressure makes the jet particles move along the set direction, reducing the irregular diffusion of the jet and increasing the jet energy density.

[0065] In addition, by precisely adjusting the drive frequency and power of the ultrasonic transducers in Step 2, the intensity and distribution of the ultrasonic field can be dynamically controlled, thereby optimizing the focusing degree and energy density of the plasma jet and ensuring the efficiency and stability of the subsequent processing process.

[0066] Step 4: Guide the plasma jet pre-focused by the ultrasonic field to the conical rotating magnetic field region, and use the conical rotating magnetic field generating device to generate a conical rotating magnetic field under the action of the conical coil iron core to perform secondary focusing and acceleration on the pre-focused plasma jet.

[0067] The purpose of Step 4 is to further accelerate the particles in the plasma jet through the action of a conical rotating magnetic field, enhance their kinetic energy, and provide higher processing efficiency and precision. Enhance the focusing effect of the plasma jet. Based on the pre-focusing in the ultrasonic field, through the focusing action of the magnetic field, the directivity and density of the jet are further improved, and the processing accuracy of the target area is increased. Through the dynamic regulation of the magnetic field, precisely control the energy distribution of the plasma jet, avoid excessive concentration or dissipation of energy, and ensure a uniform and stable processing effect. Utilize the special design of the conical rotating magnetic field to improve the stability of the jet during the processing and reduce the influence of external interference on the jet trajectory.

[0068] Specifically, in the conical rotating magnetic field generating device, a conical coil iron core is adopted, and its shape and material are precisely designed to generate a uniform and high-intensity rotating magnetic field. Through the interaction of this magnetic field with the plasma jet, the particles in the jet obtain additional accelerating kinetic energy. The rotating direction of the magnetic field matches the flowing direction of the jet, so that the particles in the plasma are accelerated along the direction of the magnetic force line, forming a tighter beam. By controlling the current intensity and frequency, the adjustable magnetic field intensity is realized, and the acceleration and focusing effects of the magnetic field on the plasma jet are optimized.

[0069] The secondary focusing and acceleration process of the conical rotating magnetic field includes: the magnetic force generated by the rotating magnetic field in its action area further focuses the already pre-focused plasma jet, reduces the divergence degree of the jet, and improves the density and energy concentration of the jet. The rotating magnetic field makes the charged particles in the plasma move in a spiral trajectory under the action of the magnetic force, increasing their speed and kinetic energy in the jet.

[0070] In Step 4, by adjusting the conical rotating magnetic field generating device and precisely controlling the intensity and characteristics of the conical rotating magnetic field, the secondary focusing and acceleration of the plasma jet can be achieved, thereby improving the speed and precision of the jet. The main ways to adjust the conical rotating magnetic field include: adjustment of magnetic field intensity, adjustment of frequency, local magnetic field adjustment, optimization of magnetic field direction and morphology.

[0071] The adjustment of magnetic field intensity is to change the intensity of the conical rotating magnetic field by adjusting the current and voltage. A strong magnetic field can accelerate the charged particles in the plasma jet, thereby increasing the speed and energy density of the jet.

[0072] The adjustment of frequency is to adjust the acceleration effect of the jet by controlling the rotation frequency of the magnetic field, so as to adapt to different processing requirements. For example, by adjusting the frequency, the efficiency of the acceleration stage can be optimized, and the acceleration speed of the jet can be controlled.

[0073] Local magnetic field adjustment is to design the change of magnetic field intensity in different regions in the magnetic field generating device according to the processing requirements, so as to achieve precise control of the jet.

[0074] The optimization of the magnetic field direction and morphology is that the morphology of the conical rotating magnetic field will directly affect the focusing effect and movement trajectory of the plasma jet. By adjusting the conical angle or position of the magnetic field, the movement path of the jet can be optimized to ensure that it remains concentrated and stable during the processing and achieves the required processing accuracy.

[0075] Through these adjustment means, it can be ensured that when the plasma jet passes through the conical rotating magnetic field region, it can act on the surface of the optical element to be processed at a high speed, concentratedly and precisely, so as to achieve an ultra-precise and non-destructive processing effect.

[0076] Step 5: Act on the surface of the optical element to be processed with the plasma jet beam after secondary focusing and acceleration by the magnetic field, and physical etching or chemical reaction occurs between the high-energy active particles in the plasma and the surface of the optical element material.

[0077] The purpose of Step 5 is to achieve high-precision and non-destructive surface processing by acting on the surface of the optical element to be processed with the plasma jet beam after secondary focusing and acceleration by the magnetic field. In this step, physical etching or chemical reaction occurs between the high-energy active particles in the plasma and the surface of the optical element, so as to perform surface modification or polishing on the optical element, improve its surface quality and processing accuracy, and meet the manufacturing requirements of ultra-precision optical elements.

[0078] Specifically, when the plasma jet beam after secondary focusing and acceleration acts on the surface of the optical element to be processed, high-energy electrons, ions, free radicals and other active particles in the plasma interact with the surface of the optical element material. These active particles can remove surface materials through mechanisms such as physical etching or chemical reactions, or rearrange surface atoms and molecules to improve the surface topography. Physical etching mainly relies on the impact and stripping of the material surface by high-energy ions and is suitable for the removal of hard optical materials. Chemical reactions occur through reactive gases or free radicals in the plasma reacting with the material to convert part of the surface layer of the material into volatile substances or oxidation products, and are suitable for fine regulation and cleaning of the material surface.

[0079] Furthermore, by adjusting the density, energy and action time of the plasma jet beam, the action intensity and depth on the surface of the optical element can be controlled. By controlling these parameters, precise control of the surface quality, roughness and processing accuracy can be achieved. By adjusting the flow rate and intensity of the plasma jet, the balance between the surface etching rate and the processing accuracy is ensured. Excessive processing may lead to over-etching, while too slow may affect the production efficiency. By finely adjusting the focusing and energy distribution of the plasma jet, the uniformity and smoothness of the surface of the optical element after processing are ensured, and uneven surface damage or fine cracks are avoided.

[0080] In addition to physical etching, the plasma can also perform surface modification. For example, a thin film can be formed through chemical reactions or the composition of surface elements can be changed to enhance the wear resistance, corrosion resistance, or optical properties of the material. By regulating the atmosphere and activation process of the plasma, directional modification of the surface of optical elements can also be achieved, such as adding an anti-reflection coating and modifying optical properties.

[0081] Example 1

[0082] Existing plasma processing methods mostly rely on a single physical force (such as electric arc, laser, etc.) to remove or surface-treat materials. In this example, the advantages of the present invention are illustrated by comparing the plasma processing methods of the present invention and the prior art.

[0083]

[0084]

[0085]

[0086] Example 2

[0087] Refer to the attached drawings of the specification Figures 2-3 , Figure 2 It is the effect diagram of processing the optical element material by the method that combines ultrasonic focusing and conical rotating magnetic field without the prior art. Figure 3 It is the effect diagram of processing the optical element material by the method of the present invention. As can be seen from Figure 2 it, the frequency of the reaction between the active ions and the material is low, the distribution of the ions is relatively disordered, and many ions fail to effectively react with the surface atoms of the material. Due to the uneven distribution of the ions, the flatness of the processed material surface is low and the surface roughness is high. As can be seen from Figure 3 it, under the action of ultrasonic focusing and conical rotating magnetic field, the ultrasonic focusing provides a local high energy density, and the active ions obtain higher energy in a specific area, thereby increasing the survival time of the ions. The Lorentz force generated by the conical rotating magnetic field further guides the active ions to form a stable rotational motion, improving the uniformity of material removal and the processing efficiency. The ions are constrained by the Lorentz force generated by the conical rotating magnetic field, concentrated in a specific area and the movement path becomes more orderly, mainly concentrated along the direction of magnetic field contraction, forming a local high electron density processing reaction area. Due to the high concentration of ions in the processing area, the material removal is more uniform and controllable, avoiding the irregular etching of random removal.

[0088] Refer to the attached drawings of the specification Figures 4-8 , the present invention also records an ultrasonic-coupled electromagnetic-controlled plasma hard and brittle element processing device, which includes a plasma conduit, a plasma generating component, an ultrasonic focusing component, a conical rotating magnetic field generating component, and an optical element material 7.

[0089] The plasma conduit consists of a straight tube structure at the upper part and a conical tube structure at the lower part. The two are connected to each other and internally communicate to jointly form the inner cavity of the plasma conduit. This inner cavity is used as the working space for the generation of plasma and the ultrasonic regulation of plasma self-organization to ensure the stable delivery and continuous flow of air flow or plasma.

[0090] Among them, the straight tube structure is located at the upper part of the plasma conduit. An air inlet is provided at its top for introducing the mixture of compressed oxygen 15 and working gas 16, so that it enters the inner cavity for reaction. The conical tube structure at the lower part is tapered and contracted, with the cone angle facing downwards. An air outlet is provided at its bottom end for outputting the formed plasma. After the plasma undergoes stable flow and ultrasonic regulation in the inner cavity, it acts on the surface of the optical element material 7 below through the air outlet. During this process, physical and chemical reactions occur between the plasma and the atoms on the material surface, realizing high-precision and non-damaging surface modification and processing, and ensuring high-quality treatment effects on the material surface.

[0091] In addition, the structural design of the plasma conduit helps to optimize the stability and uniformity of the plasma, improve the controllability of the processing process, and is applicable to the surface treatment requirements of different types of optical materials.

[0092] In the implementation mode of this application, the conical barrel structure of the plasma conduit is the nozzle 10 shown in the attached drawings of the specification Figure 4 The nozzle 10 optimizes the air flow distribution through a precisely designed structure to enhance the stability and uniformity of the plasma jet. The nozzle 10 can adopt a specific inner wall curvature or a multi-stage contraction and expansion structure to regulate the air flow velocity and pressure distribution to ensure the action effect of the plasma in the target area. At the same time, the material of the nozzle 10 can be selected as a material with high temperature resistance and plasma erosion resistance, such as ceramics or superalloys, to improve durability and reduce interference with the jet characteristics.

[0093] The plasma generating component includes a high-voltage tungsten needle electrode 5, a gas pressure reducing mixer 12, and a frequency conversion matching controller 13. The high-voltage tungsten needle electrode 5 is fixedly installed at the inner center of the top of the straight tube structure of the plasma conduit, and its tip faces the inner cavity of the plasma conduit to ensure stable discharge. The tail of the electrode is connected to the frequency conversion matching controller 13 through an insulating high-voltage tungsten needle electrode base. The frequency conversion matching controller 13 can accurately adjust the discharge parameters, such as voltage, frequency, and power, etc., so as to optimize the plasma generation process, improve the discharge stability and plasma activity.

[0094] The gas pressure reducing mixer 12 is responsible for proportionally mixing and regulating the pressure of the working gas to optimize the plasma environment. The gas pressure reducing mixer 12 is connected to the inlet of the plasma conduit through a pipeline, mixes compressed oxygen 15 and the working gas 16 according to a preset ratio, and reduces the pressure of the mixed gas so that it stably flows into the inner cavity of the plasma conduit within a set pressure range. Appropriate gas flow rate and pressure can not only improve the stability of the plasma, but also effectively control the physical parameters of the discharge area to meet different application requirements.

[0095] To enhance the structural stability and discharge reliability, the plasma generating component further includes an insulating high-voltage tungsten needle electrode base 3 and a high-voltage tungsten needle electrode fastening screw 4. The insulating high-voltage tungsten needle electrode base 3 is installed on the top of the straight cylinder structure of the plasma conduit to provide electrical insulation and mechanical fixation. The inlet of the mixed gas of compressed oxygen 15 and the working gas 16 is opened on the insulating high-voltage tungsten needle electrode base 3, such as the mixed gas inlet 8 shown in the attached Figure 4 specification. The high-voltage tungsten needle electrode 5 is locked at the center of the insulating high-voltage tungsten needle electrode base 3 through the high-voltage tungsten needle electrode fastening screw 4 to ensure its precise positioning and no displacement or loosening during long-term operation.

[0096] In the implementation mode of the present application, the working gas 16 can be selected according to the material characteristics of different optical elements, including but not limited to argon (Ar), carbon tetrafluoride (CF4), or sulfur hexafluoride (SF6), etc. These gases can be used alone or mixed in a specific ratio to meet the plasma processing requirements of different materials. For example, argon can be used to improve the discharge stability, while carbon tetrafluoride or sulfur hexafluoride is suitable for enhancing the chemical reaction activity to optimize the effect of the plasma on the target material.

[0097] The plasma generating component also includes a manual pressure reducing valve 14. The cylinders of compressed oxygen 15 and the working gas 16 are respectively connected to the gas pressure reducing mixer 12 through independent pipelines, and a manual pressure reducing valve 14 is provided on each pipeline to independently regulate and control the gas pressure to ensure stable and controllable gas supply at the input end of the mixer 12.

[0098] The ultrasonic focusing component includes an annular ultrasonic array controller 1 and an annular ultrasonic array 9 located below the high-voltage tungsten needle electrode 5. The annular ultrasonic array 9 is composed of a plurality of ultrasonic emission units 19, and these ultrasonic emission units 19 are evenly distributed and embedded in the straight cylinder structure of the plasma conduit. The annular ultrasonic array controller 1 realizes synchronous driving and phase control of the ultrasonic array 9 through precise signal regulation to form a specific ultrasonic focusing mode.

[0099] Specifically, multiple ultrasonic transmitting units 19 in the annular ultrasonic array 9 are uniformly arranged along the axial and radial directions of the plasma catheter at a preset interval, and can form a single-layer or multi-layer annular structure to optimize the distribution of ultrasonic energy in the plasma region. Each ultrasonic transmitting unit 19 is connected in series or parallel with adjacent units through flexible wires or integrated circuit ribbon cables to ensure the stability and consistency of signal transmission of the entire array. The series connection method is suitable for driving with low voltage and high current, which can reduce line loss and improve energy utilization efficiency. The parallel connection method is suitable for driving with high voltage and low current, which can improve the system redundancy. Even if some units fail, other units can still work normally. In actual design, the series-parallel connection mode can also be combined to optimize the circuit characteristics and ensure the efficiency of ultrasonic coherent synthesis. The ultrasonic transmitting unit 19 is made of piezoelectric ceramics or other ultrasonic transducer materials, and its resonance frequency matches the working environment to ensure the efficient propagation of ultrasonic waves and their action on the plasma region.

[0100] The annular ultrasonic array controller 1 is connected to each ultrasonic transmitting unit 19 through an independent signal driving line, providing a high-frequency alternating current signal to drive the ultrasonic transducer to vibrate and generate ultrasonic waves. The annular ultrasonic array controller 1 is used to precisely control the working state of the annular ultrasonic array 9. Through phase control, amplitude adjustment, frequency matching and mode switching, the focusing and energy optimization of ultrasonic waves are achieved. Phase control is used to adjust the phase of the excitation signal of each ultrasonic transmitting unit 19 to form a specific ultrasonic interference effect, and focus the ultrasonic energy in the target area through phased array technology, thereby enhancing the energy density of the plasma. The amplitude adjustment dynamically adjusts the driving voltage or power of each unit according to the real-time monitored data to optimize the effect of ultrasonic waves. The frequency matching adjusts the driving signal frequency according to the plasma working environment and material characteristics, so that the ultrasonic waves match the natural vibration frequency of the plasma, improve the coupling efficiency of ultrasonic energy, and enhance the stability of the plasma. In addition, the controller can perform mode switching to set different ultrasonic working modes, such as diffusion mode, focusing mode or frequency sweep mode, to adapt to different working conditions. For example, the diffusion mode is adopted in the initial stage to improve the plasma uniformity; the focusing mode is switched to in the processing stage to increase the local energy density, thereby optimizing the effect of the plasma.

[0101] The conical rotating magnetic field generating component is embedded in the nozzle 10, and its conical structure makes the plasma jet spiral accelerate and contract from the large end to the small end of the magnetic field. The conical rotating magnetic field generating component includes a conical rotating magnetic field generating device 2, a conical coil 6, an insulating sheet 17 and a conical coil iron core 18.

[0102] The conical coil iron core 18 is made of a high magnetic permeability material. Its outer surface is precisely matched with the inner surface of the conical structure of the plasma duct to ensure the uniformity of the magnetic field distribution. Its function is to focus and guide the magnetic field generated by the coil, improve the magnetic induction intensity, and enhance the stability and control accuracy of the rotating magnetic field. A plurality of conical coils 6 are evenly arranged around the surface of the conical coil iron core 18 and arranged at a certain interval. The conical coil 6 is a 12-pole three-phase coil. After these coils are energized, a rotating magnetic field is generated on the iron core surface. Through corresponding drive control, the direction, intensity, and rotation speed of the magnetic field can be adjusted to meet the requirements of different plasma working conditions.

[0103] The insulating sheet 17 is installed outside each conical coil 6 to cover its entire area. The insulating sheet is made of a high heat-resistant and high voltage-resistant material. Its function is to provide electrical isolation, prevent short circuits between coils, and optimize thermal management to reduce the heat accumulation generated by the coils during long-term operation. The conical rotating magnetic field generating device 2, as the core drive control unit, is responsible for providing alternating current to the conical coils 6 to form an adjustable rotating magnetic field. The conical rotating magnetic field generating device 2 is used to precisely control the current parameters of the conical coils 6 to form a stable rotating magnetic field, improve the confinement ability and uniformity of the plasma. Through phase regulation, the current phase difference of each coil is adjusted to make the magnetic field rotate in the set direction and optimize the spatial distribution of the magnetic field to ensure uniform magnetic field action. Through frequency control, the frequency of the alternating current is dynamically adjusted according to the working parameters of the plasma to make the magnetic field match the characteristics of the plasma, thereby enhancing the stable confinement effect of the magnetic field on the plasma. Through magnetic field intensity adjustment, the input current amplitude of the coil is adjusted according to the real-time working conditions to precisely control the magnetic field intensity, further optimize the stability and uniformity of the plasma, and improve the working efficiency of the overall system.

[0104] In the implementation mode of the present application, the conical coil 6 and the conical coil iron core 18 adopt a closely fitting structure to ensure efficient magnetic field conduction and reduce magnetic flux loss. The insulating sheet 17 is installed between the conical coil 6 and the external environment to ensure electrical isolation between each coil unit and prevent short circuits or damage caused by high-voltage breakdown. Each conical coil 6 is connected to the conical rotating magnetic field generating device 2 through an independent wire and is uniformly powered and controlled by this device to achieve the rotational control of the magnetic field. The drive current of the conical coil 6 adopts a multi-phase alternating mode (such as three-phase or multi-phase alternating current) to form a stable rotating magnetic field and improve the magnetic confinement ability of the plasma. In different application scenarios, the arrangement spacing of the conical coils 6 can be adjusted according to the magnetic field intensity requirements to adapt to different plasma working conditions.

[0105] To achieve reliable connections between the annular ultrasonic array 9 and the annular ultrasonic array controller 1, as well as between the conical coil 6 and the conical rotating magnetic field generating device 2, wire through-holes need to be opened at corresponding positions on the plasma catheter to ensure the stability of signal and power transmission while avoiding affecting the working environment of the plasma. To ensure the airtightness and electrical insulation of the plasma catheter, the wire through-holes need to be sealed to prevent the external environment from affecting the stability of the plasma. Silicone rubber, high-temperature resistant epoxy resin, or ceramic sealing materials can be used to fill the through-holes to prevent high-temperature leakage or electrical breakdown. Alternatively, the through-holes can be protected by a double layer of an O-ring + high-temperature ceramic sleeve to improve pressure resistance and airtightness. Or a high-temperature resistant polyimide coating can be added to the surface of the wire to enhance the electrical insulation performance.

[0106] The ultrasonic coupling electromagnetic controlled plasma brittle element processing device of the present application utilizes the synergistic effect of the ultrasonic field and the magnetic field to achieve a high-density and high-energy plasma jet beam to meet the requirements of high-efficiency, low-damage, and ultra-precision processing. Its working principle is as follows:

[0107] First, compressed oxygen 15 and working gas 16 are mixed by the gas pressure reducing mixer 12 and the mixed gas is input into the plasma catheter through the mixed gas inlet 8. The high-voltage tungsten needle electrode 5 generates a high-voltage arc under the precise control of the frequency conversion controller 13. However, in the initial state, the arc is disordered and vulnerable to external interference. Subsequently, the high-voltage arc passes through the annular array 9. Under the action of the ultrasonic sound field, the ultrasonic pressure dynamically modulates the arc, causing the arc to contract and the direction to be stable, and a plasma jet 20 is formed in the inner cavity of the plasma catheter. Subsequently, the stabilized plasma jet enters the conical rotating magnetic field 22, which is generated by the 12-pole conical three-phase coil 6 and precisely controlled by the conical rotating magnetic field generating device 2. The magnetic field exerts a Lorentz force on the charged particles in the plasma, causing them to move in a spiral contraction along the trajectory of the magnetic induction line 21. The plasma gains kinetic energy during the contraction process from the large end to the small end of the magnetic field, and its density and energy are increased, forming a high-energy focused jet beam. Finally, the high-energy plasma jet is precisely ejected onto the surface of the optical element material 7 placed on the workbench 11 through the nozzle 10 of the plasma catheter, and physical etching or chemical reactions occur with the material atoms to achieve non-damaging and high-precision surface modification and micro-structure processing. To adapt to different optical materials, the type and proportion of the working gas 16 can be adjusted. For example, argon (Ar) is used to improve the discharge stability, and carbon tetrafluoride (CF4) or sulfur hexafluoride (SF6) is used to enhance the chemical reaction activity to optimize the processing effect. Through the synergistic effects of stabilizing the jet by the ultrasonic field, focusing and accelerating by the magnetic field, and optimizing the control of the working gas, the density, directivity, and processing precision of the plasma are greatly improved in this device, ensuring high-quality processing of optical elements and being applicable to the field of ultra-precision manufacturing.

[0108] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics known in the art are not described in detail herein. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A method for ultrasonically assisted magnetron plasma polishing of hard and brittle components, characterized in that: The method comprises: Step 1: Mix the working gas and compressed oxygen in a preset ratio, and adjust the pressure through a gas pressure reducing mixer so that the mixed gas flows stably into the inner cavity of the plasma guide tube; Step 2: Ionize the mixed gas under high frequency and high voltage through a high-voltage tungsten needle electrode to generate a plasma jet, and adjust the discharge parameters through a variable frequency matching controller; Step 3: passing the plasma jet through an annular ultrasonic array, and forming a high-intensity ultrasonic field under the drive of the annular ultrasonic array controller, using the ultrasonic field to suppress the arc divergence disorder state, so that it transforms into a concentrated and ordered state, and regulates the motion trajectory of the plasma to pre-focus the plasma jet; Step 4: guiding the plasma jet pre-focused by the ultrasonic field to the conical rotating magnetic field area, using the conical rotating magnetic field generating device to generate a conical rotating magnetic field under the action of the conical coil core, and performing secondary focusing and acceleration on the pre-focused plasma jet; Step 5: Apply the plasma jet beam after secondary focusing and acceleration by the magnetic field to the surface of the optical element to be processed, and the high-energy active particles in the plasma will physically etch or chemically react with the surface of the optical element material.

2. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: In step 3, the formation process of the ultrasonic field includes: the ultrasonic transducer array is arranged in a ring shape, and when the ultrasonic transducer receives the high-frequency electrical signal emitted by the driving power supply, the electrical energy is quickly converted into mechanical vibration to generate high-frequency ultrasonic waves. The ultrasonic wave propagates in the air medium, forming alternating compression waves and rarefaction waves, and generating a highly focused acoustic field structure in the plasma jet area.

3. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: In step 3, by adjusting the driving frequency and power of the ultrasonic transducer, the intensity and distribution of the ultrasonic field can be dynamically controlled, thereby optimizing the focusing degree and energy density of the plasma jet.

4. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: The secondary focusing and acceleration process of the conical rotating magnetic field includes: the magnetic force generated by the rotating magnetic field in its action area further focuses the pre-focused plasma jet, reduces the divergence of the jet, and increases the density and energy concentration of the jet. The rotating magnetic field causes the charged particles in the plasma to move in a spiral trajectory under the action of the magnetic field force, increasing their speed and kinetic energy in the jet.

5. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: In step 5, physical etching is the impact and peeling effect of high-energy ions on the surface of the material; chemical reaction is the chemical reaction between the reactive gas or free radicals in the plasma and the material, converting part of the surface layer of the material into volatile substances or oxidation products.

6. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: In step 5, physical etching is suitable for removing hard optical materials, and chemical reaction is suitable for finely controlling and cleaning the material surface.

7. The method for ultrasonically assisted magnetron plasma polishing of hard and brittle components according to claim 1, characterized in that: In step 1, the working gas includes but is not limited to one or more of argon, carbon tetrafluoride, and sulfur hexafluoride.

8. An ultrasonically coupled electromagnetically controlled plasma hard and brittle component processing device, characterized in that: The device is used to implement the ultrasonic assisted magnetron plasma polishing method for hard and brittle components according to any one of claims 1 to 7; the device comprises a plasma guide tube (3), a plasma generating component, an ultrasonic focusing component and a conical rotating magnetic field generating component, wherein: A plasma conduit (3), the plasma conduit (3) having an inner cavity, a mixed gas inlet of compressed oxygen and working gas being provided at the top, and a gas outlet being provided at the bottom, an optical element material to be processed being placed below the gas outlet, and the gas outlet being used to direct the high-energy focused jet beam to act on the surface of the optical element material to be processed; A plasma generating component comprises a high-voltage tungsten needle electrode (5), wherein the high-voltage tungsten needle electrode (5) is arranged at the top of the inner cavity of the plasma conduit (3); the high-voltage tungsten needle electrode (5) is used for discharging and ionizing the mixed gas to form a plasma jet; An ultrasonic focusing component comprises an annular ultrasonic array (9) located below the high-voltage tungsten needle electrode (5), the annular ultrasonic array (9) being composed of a plurality of ultrasonic transmitting units (19), each of the ultrasonic transmitting units (19) being evenly distributed and embedded in the inner cavity wall of the plasma conduit (3); the annular ultrasonic array (9) is used to generate an ultrasonic sound field and pre-focus the plasma jet; The conical rotating magnetic field generating component comprises a conical coil (6) and a conical coil core (18). The conical coil core (18) is arranged in the inner cavity of the plasma conduit (3) and below the annular ultrasonic array (9), with its conical opening facing downward and connected to the gas outlet of the plasma conduit (3). A plurality of conical coils (6) are evenly arranged around the surface of the conical coil core (18). The conical coil (6) is used to generate a conical rotating magnetic field when a focused plasma jet passes through, so that the plasma jet performs a spiral contraction motion along a magnetic flux line trajectory to obtain kinetic energy gain, thereby forming a high-energy focused jet beam.

9. The ultrasonically coupled electromagnetically controlled plasma hard and brittle component processing device according to claim 8, characterized in that: The plasma generating component further comprises a gas decompression mixer (12) and a frequency conversion matching controller (13), the electrode tail of the high-voltage tungsten needle electrode (5) is connected to the frequency conversion matching controller (13), and the gas decompression mixer (12) is connected to the gas inlet of the plasma guide tube through a pipeline; The conical rotating magnetic field generating component further comprises an insulating sheet (17), which is installed outside each conical coil (6) and covers the entire area of ​​the conical coil (6).

10. The ultrasonically coupled electromagnetically controlled plasma hard and brittle component processing device according to claim 8, characterized in that: The plasma conduit is composed of an upper straight tube structure and a lower conical tube structure, which are interconnected and internally connected to form an inner cavity of the plasma conduit; the straight tube structure is located at the upper part of the plasma conduit, and an air inlet is arranged at the top; the lower conical tube structure is conically contracted, with the cone angle facing downward, and an air outlet is arranged at the bottom; the outer profile of the conical coil core (18) matches the inner profile of the conical tube structure of the plasma conduit.

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