A seed electron-based multi-physical field assisted laser micro-machining method and device

Abstract

The application discloses a seed electron-based multi-physical field assisted laser micro-machining method, which comprises the following steps: introducing an ionized gas flow into a laser and material interaction region; the ionized gas flow is ionized by high-voltage discharge, and a high-speed gas flow containing free electrons and charged ions is formed; the ionized gas flow is used to transport free electrons to the laser and material interaction region; the free electrons act as seed electrons to promote avalanche ionization, accelerate the phase change and ionization process of the material after absorbing laser energy, and reduce the ablation threshold of the material; the high-speed gas flow is used to discharge the ablation products from the machining area, and simultaneously plays a cooling role on the machining area; the ionized gas flow forms a space electric field at the interface of the laser and the material interaction to constrain the expansion of the machining area plasma and make the ablation debris charged to inhibit the agglomeration deposition, so that the quality of the material machining surface is improved.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, specifically relating to a multi-physics field-assisted laser microprocessing method and apparatus based on seed electrons. Background Technology

[0002] Laser processing is an advanced manufacturing technology that utilizes the interaction between laser light and materials to achieve processing. It is a typical non-contact micromachining technology. Laser ablation of materials exhibits a significant threshold effect; effective processing can only occur when the laser energy density exceeds the material's ablation threshold. The ablation threshold, as a crucial parameter in laser processing, plays a vital role in energy control during the process. Insufficient laser energy fails to achieve effective material removal, while excessively high laser energy may exacerbate thermal damage, affecting processing quality and increasing energy consumption. Laser micromachining relies on microscopic processes such as liquefaction / vaporization, plasma expansion, sputtering deposition of ablation products, and heat conduction after the material absorbs laser energy. This process presents challenges including poor processing accuracy, the presence of recast layers and microcracks on the surface, and thermal damage.

[0003] To address the above issues, scholars both domestically and internationally have proposed laser micromachining methods assisted by gas, water, ultrasonic vibration, electric / magnetic fields, or a combination of multiple fields. These methods have improved the efficiency and precision of laser micromachining and enhanced the surface quality. For example, the literature Applied Surface Science, 2004, 230(1): 50-59 reported on helium-assisted femtosecond laser micromachining, finding that flowing helium can effectively prevent oxidation of the processed surface and remove debris generated in the processing area, thereby improving material removal rate and surface quality. The literature Applied Physics Letters, 2016, 108(25): 254103 studied magnetic field-assisted nanosecond laser processing technology, finding that the magnetic field can effectively confine laser-induced plasma, improve the absorption of laser energy by the material, thereby reducing the ablation threshold and improving processing quality. The paper *International Journal of Machine Tools and Manufacture*, 2020, 150: 103510, describes the use of coaxial water jet-assisted nanosecond laser machining of film cooling holes in nickel-based turbine blades. It found that increasing the water jet velocity significantly reduces the thickness of the heat-affected zone (HAZ) on the hole wall. When the water jet velocity is ≥5.1 m / s, even with a laser energy density far exceeding the material ablation threshold, high-quality micropores free from defects such as oxide layers, recast layers, HAZ, and microcracks can be obtained. Multi-mode combined laser micromachining methods integrate the advantages of single-mode methods, further improving the efficiency and quality of laser micromachining. However, these methods involve numerous devices, complex operations, and are difficult to integrate into applications.

[0004] In recent years, scholars have proposed a multi-energy field micromachining method combining laser and plasma jet processing. Patent CN119549888A, published as a "laser-plasma composite processing device and method for curved microstructures," uses plasma jets as the primary processing method. The jet generated by the plasma source and nozzle delivers active and high-energy particles to the processing area. Simultaneously, a femtosecond laser is introduced into the plasma generation or processing area to regulate the particle energy in the plasma jet and preheat the processing area, thereby improving the stability of particle energy and processing efficiency. This method is suitable for localized processing of curved microstructures. The advantage of this method lies in its ability to improve the consistency and efficiency of plasma jet processing through shaping the plasma jet and laser preheating. Its technical focus is "plasma jet processing as the main method and laser as a supplementary method," meaning the plasma jet is used for workpiece processing, while the laser is mainly used to regulate the particle energy of the plasma jet or for surface preheating. Patent CN109048088B, published as a "method and device for composite processing of microholes using long-pulse laser and plasma jet," discloses a method and device for processing microholes using a combination of long-pulse laser and plasma jet processing. The typical process is as follows: first, a long-pulse laser is used to drill the hole; then, the plasma jet nozzle is rotated or switched to be aimed at the drilled micro-hole. The plasma jet cleans the slag on the inner wall of the hole and improves the hole wall properties. The advantage of this approach is that it uses a plasma jet to remove splashed slag and improve the hole wall quality after laser drilling. However, the process is clearly a two-stage sequential process of "laser first, then plasma," with the plasma jet mainly playing a post-processing role in micro-hole cleaning.

[0005] While the above-mentioned solutions can improve the surface quality or processing efficiency of laser processing to some extent, overall, the existing technologies still have several unresolved issues:

[0006] 1. The mechanism of action is singular and difficult to control the microscopic process of laser-material interaction: Auxiliary methods such as gas, water, ultrasonic vibration, and electric / magnetic fields can only passively improve the negative effects of laser processing through a single action, but they are difficult to actively control the microscopic process of laser-material interaction. Patent CN119549888A focuses on using laser to control the energy distribution of plasma particles and preheat the plasma jet processing area; essentially, it is laser-assisted plasma jet processing. Patent CN109048088B uses plasma as a cleaning / modification method after laser drilling. Neither of these uses plasma jets as a means to directly intervene in the microscopic interaction process of "laser-material".

[0007] 2. Unable to reduce the ablation threshold of materials: Traditional auxiliary methods mainly address the negative effects already generated during laser micromachining, but cannot improve laser energy utilization and processing efficiency from the perspective of controlling microscopic processes such as material phase transition ionization and reducing the ablation threshold of materials.

[0008] 3. Multi-physics field integration is difficult and the process is complex: Although traditional multi-physics field assistance can improve the quality of laser micro-machining by comprehensively utilizing two or more auxiliary mechanisms, the integration is difficult and may even require significant modifications to the equipment structure, timing switching or vacuum / fixture conditions (such as coupling of water supply system and ultrasonic device, rotary switching device, etc.), which makes it difficult to achieve both process integration and automation, thus limiting industrial promotion.

[0009] In summary, although various physical field-assisted and plasma composite processing approaches have been proposed and widely used, and have achieved certain results in improving processing efficiency and quality, there is still a lack of a multi-physics field-assisted laser micro-processing method that can control the microscopic process of laser-material interaction in real time, thereby systematically and controllably reducing the material ablation threshold, improving material removal efficiency, and improving surface processing quality. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and solve the problems that the physical fields used in the prior art are difficult to actively control the microscopic processes such as laser-material interaction and material phase transition ionization, and cannot fundamentally control the key factors affecting the efficiency, quality and precision of laser micromachining. This invention provides a multi-physics field assisted laser micromachining method and device based on seed electrons. This invention can actively control the material ionization and phase transition process in real time, and at the same time has the functions of reducing laser propagation loss, promoting chip removal and cooling, and inhibiting oxidation of the processed surface, thereby improving the efficiency of laser micromachining and improving the quality of the processed surface.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A multiphysics-assisted laser microfabrication method based on seed electrons includes the following steps:

[0013] An ionized gas flow is introduced into the region where the laser interacts with the material. The ionized gas flow is ionized by high-voltage (1-40KV voltage) discharge to form a high-speed gas flow containing free electrons and charged ions.

[0014] The ionized gas flow provides free electrons in the laser-material interaction region. These free electrons act as seed electrons to promote avalanche ionization after the material absorbs laser energy, thereby accelerating the phase transition and ionization process of the material and reducing the ablation threshold of the material.

[0015] The high-speed airflow is used to discharge the ablation products from the processing area, while simultaneously cooling the processing area.

[0016] The ionized gas flow forms a spatial electric field at the interface where the laser interacts with the material to constrain the plasma expansion of the material in the processing area and charge the ablation debris to suppress agglomeration and deposition, thereby improving the quality of the processed surface.

[0017] The ionized gas flow isolates the laser-material interaction area from direct contact with air, suppressing the oxidation of the processed surface by oxygen and thus improving the surface quality.

[0018] Furthermore, the gas is one or more of nitrogen, helium, or argon.

[0019] Furthermore, the ionization gas flow rate is 0.5–100 m / s to balance debris removal and cooling effect.

[0020] Furthermore, the ionized gas flow is directed through the nozzle assembly to the laser-material interaction region to ensure efficient injection of free electrons; the angle between the nozzle assembly and the laser beam propagation direction is 0°–90°.

[0021] Furthermore, the spatial electric field strength is in the range of 0.1–20 kV / cm to ensure effective confinement of the high-density plasma expansion formed by material phase transition.

[0022] Furthermore, the ionized gas flow forms an oxygen-free atmosphere with a diameter on the order of millimeters in the laser-material interaction region, preventing the processed surface from being oxidized by air.

[0023] Furthermore, this method can be applied to microstructure processing, thin film peeling, or material surface modification, where microstructures include micropores, trenches, and micropits.

[0024] Preferably, the present invention also provides a multiphysics-assisted laser micromachining device based on seed electrons, comprising:

[0025] A laser unit is used to generate a focused laser beam and focus the laser beam onto the surface of the workpiece being processed.

[0026] A gas supply unit is used to supply the gas to be ionized;

[0027] A gas ionization device is used to discharge gas from a gas supply unit, causing it to ionize and form an ionized gas stream.

[0028] A nozzle assembly, disposed at the injection end of the gas ionization device, is used to directionally inject the ionized gas flow into the laser-material interaction region;

[0029] A power supply unit is used to provide driving power for the gas ionization device;

[0030] The control unit is configured to synchronously control the position, time and power of the laser unit and the gas ionization device according to a predetermined program, so that the ionized gas flow acts on the laser-material interaction interface within the laser action time window;

[0031] The worktable is used to move the workpiece relative to it to complete the required machining path.

[0032] The workbench controller is used to control the movement of the workbench.

[0033] Furthermore, it also includes sensors for providing feedback signals from the processing area to the control unit in real time; the control unit adaptively adjusts the pulse energy of the laser and the ionization gas flow parameters based on the feedback signals to optimize the processing quality; the feedback signals include emission spectrum, temperature field, and three-dimensional morphology or roughness data of the processed surface.

[0034] Preferably, the present invention also provides a non-transitory computer-readable storage medium storing program instructions for running on a processor, wherein the program instructions, when executed, cause the processor to perform the steps of the multiphysics-assisted laser micromachining method, including: controlling laser emission, controlling the discharge timing of the gas ionization device, controlling the positioning and flow rate of the nozzle assembly, and adjusting the above parameters according to feedback signals.

[0035] Furthermore, the program instructions also include a feedback-based closed-loop control module, which adjusts the laser pulse parameters and ionization gas discharge parameters based on emission spectrum, temperature field, three-dimensional morphology of the processed surface, and roughness data.

[0036] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0037] 1. Reduce ablation threshold and improve energy utilization: Traditional methods cannot fundamentally change the phase transition ionization process after the material absorbs laser energy, making it difficult to improve laser energy utilization. This invention utilizes free electrons in the ionized gas flow as seed electrons to promote avalanche ionization after the material absorbs laser energy. Therefore, the material of the workpiece can complete phase transition and ionization at a lower laser power, effectively reducing the ablation threshold and thus achieving material ablation processing at a lower power, thereby improving laser energy utilization.

[0038] 2. Improve processing efficiency and chip removal capability: In existing methods, slag and debris deposition is severe, making it difficult to achieve efficient chip removal and cooling simultaneously during laser action, resulting in energy loss and repeated heating; the technical solution of this invention can quickly remove ablation products through high-speed ionized gas flow, avoiding their absorption and scattering of laser energy; significantly improving processing efficiency and reducing the problems of recast layer and debris deposition.

[0039] 3. Reduce heat damage and improve surface quality: Traditional methods have problems such as large heat-affected zones, surface microcracks and recast layers; this invention uses high-speed ionized gas flow to cool the processing zone, reducing heat accumulation and the formation of microcracks and heat damage layers.

[0040] 4. Suppressing debris agglomeration and deposition: Existing technologies lack effective control over debris agglomeration and deposition; This invention utilizes the spatial electric field formed by ionized gas flow in the processing area to charge the debris, causing them to repel each other, thus suppressing their agglomeration and deposition and solidification on the surface, and improving the quality of the processed surface.

[0041] 5. Suppressing oxidation of the processed surface: Traditional methods mostly achieve material ablation in an air atmosphere, which makes it difficult to avoid oxidation of the processed surface by the air, which has an adverse effect on the surface quality; This invention uses ionized gas flow to isolate the air in the laser-material interaction area, and the resulting oxygen-free atmosphere can prevent the processed surface from being oxidized by the air, further improving the quality of the processed surface.

[0042] 6. Combining the advantages of multiple physical fields: Existing technologies are difficult to integrate multiple auxiliary mechanisms, resulting in limited auxiliary effects on laser micromachining and an inability to actively control the microscopic processes of laser-material interaction; This invention cleverly integrates the functions of seed electron-induced material phase transition ionization, high-speed airflow chip removal and cooling, spatial electric field-constrained ablation and deposition of debris, and oxygen-free atmosphere to suppress surface oxidation in an integrated system, and can realize real-time control of the microscopic processes of laser micromachining.

[0043] 7. Real-time coupling and closed-loop control: This invention synchronizes the ionization gas flow, gas flow rate, discharge intensity and laser parameters in time and adjusts them in real time based on feedback signals, thereby improving the efficiency and surface quality of micro-machining and ensuring the stability and consistency of the processing.

[0044] In summary, this invention improves the efficiency of laser micromachining and enhances the surface quality of the processed material by applying an ionized gas flow to the laser-material contact area, regulating the laser-material interface, promoting microscopic processes such as material phase transition and ionization, reducing the material ablation threshold, promoting cooling of the processing area and debris removal by using high-speed gas flow, suppressing debris agglomeration and deposition by using a spatial electric field, and suppressing surface oxidation by using an oxygen-free atmosphere. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the multiphysics-assisted laser micromachining device in an embodiment of the present invention.

[0046] Figure 2 This illustrates the effect of different processing methods on the ablation threshold of silicon in embodiments of the present invention.

[0047] Figure 3aThis is a schematic diagram of the surface morphology obtained by pure laser ablation.

[0048] Figure 3b This is a schematic diagram of the surface morphology obtained by conventional airflow-assisted laser ablation.

[0049] Figure 3c This is a schematic diagram of the surface morphology obtained by laser ablation assisted by ionized gas flow.

[0050] Figures 4a to 4c These are images of the microgroove morphology obtained under different auxiliary processing methods.

[0051] Figure 5 A comparison chart showing the volume of material removed under different processing methods.

[0052] Reference numerals: 1-Control unit, 2-Laser, 3-Beam expander, 4-Attenuator, 5-Reflector, 6-Focusing lens, 7-Focused laser beam, 8-Workpiece, 9-Worktable, 10-Worktable controller, 11-Gas source, 12-Gas ionization device, 13-Ionized gas flow, 14-High voltage power supply unit Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides a multi-physics field-assisted laser micromachining device based on seed electrons, including: a control unit 1, a laser unit, a worktable 9, a worktable controller 10, a gas source 11, a gas ionization device 12, and a high-voltage power supply unit 14.

[0056] The laser unit generates a focused laser beam and focuses it onto the surface of the workpiece 8. The laser unit includes a laser 2, a beam expander 3, an attenuator 4, a reflector 5, and a focusing lens 6. The reflector 5 is positioned at a 45° angle to the horizontal plane. The laser beam emitted from the laser 2 passes sequentially through the beam expander 3 and the attenuator 4 before entering the reflector 5. After being reflected by the reflector 5, it passes through the focusing lens 6 to form a focused laser beam 7, which is then incident on the workpiece 8. Both the reflector 5 and the focusing lens 6 are located directly above the workpiece 8.

[0057] The workpiece 8 to be processed is placed on the worktable 9, which is connected to the worktable controller 10. The worktable controller 10 is used to control the displacement of the worktable 9 to complete the required processing path.

[0058] The control unit 1 is connected to the laser 2 and the gas ionization device 12 respectively, and the high-voltage power supply unit 14 is connected to the gas ionization device 12. The control unit 1 is configured to synchronously control the position, time and power of the laser unit and the gas ionization device according to a predetermined program, so that the ionized gas flow acts on the interface between the laser and the material within the laser action time window. The high-voltage power supply unit 14 is used to provide driving voltage for the gas ionization device, and the voltage range is 1-40KV.

[0059] The gas ionization device 12 is used to discharge the gas from the gas source 11, so as to ionize it and form an ionized gas flow. The gas source 11 and the gas ionization device 12 are connected by a pipeline to ensure that the gas to be ionized enters the gas ionization device 12 through the pipeline and forms an ionized gas flow 13 under the excitation of a high-voltage power supply.

[0060] Gas source 11 serves as a gas supply unit, used to provide the gas to be ionized, which is one or more of nitrogen, helium, or argon.

[0061] The nozzle assembly, located at the injection end of the gas ionization device 12, is used to directionally inject the ionized gas flow into the laser-material interaction region; here, the material corresponds to the material of the workpiece 8 being processed.

[0062] The processing device is also equipped with sensors to provide feedback signals from the processing area to the control unit 1 in real time. The control unit 1 adaptively adjusts the laser pulse parameters and ionization gas discharge parameters based on the feedback signals to optimize the processing quality. The feedback signals include data such as emission spectrum, temperature field, three-dimensional morphology of the processed surface, and roughness.

[0063] During workpiece processing, laser processing parameters are input through the control unit 1, and the focused laser beam 7 is adjusted to focus on the surface of the workpiece 8. At the same time, the gas source 11 is turned on to allow high-speed airflow to enter the gas ionization device 12. The discharge parameters are adjusted to generate a suitable ionized airflow 13. The position of the nozzle assembly is adjusted so that the ionized airflow 13 acts on the spot of the focused laser beam 7 on the surface of the workpiece 8. Combined with the processing path set by the worktable controller 10, the micro-processing of the workpiece 8 is achieved.

[0064] Example 2

[0065] This embodiment employs an ionized gas flow-assisted laser micromachining method to perform grooving on silicon. The laser 2 used generates a focused laser beam 7 with a wavelength of 1030 nm, a pulse width of 300 fs, and a repetition frequency of 100 kHz. The laser power is adjusted to 5.6 W. The gas source 11 for generating the ionized gas flow 13 is high-purity helium gas with a flow rate of 2.5 L / min. After being excited and discharged by a high-voltage power supply, it forms an ionized gas flow 13 containing free electrons and charged ions, with a velocity of approximately 14 m / s. The angle between the focused laser beam 7 and the ionized gas flow 13 is 60°. The laser processing parameters are adjusted by the control unit 1 to perform silicon surface ablation. The ablation threshold of silicon under different pulse numbers is calculated, and the results are as follows: Figure 2 As shown, compared to pure laser and ordinary helium gas flow assistance, ionized gas flow assistance can effectively reduce the ablation threshold of silicon, with a maximum reduction of up to 20%. During ionized gas flow assisted laser processing, high-density free electrons are transported to the laser-material interaction region. These free electrons, acting as seed electrons, promote the development of avalanche ionization, thus accelerating the microscopic processes such as phase transition and ionization after the material absorbs laser energy, thereby achieving ablation removal of the material at a lower laser power.

[0066] When the ionized gas flow acts on the processing area, it forms a high-speed inert gas flow, which can remove ablation products from the processing area, reduce the absorption and shielding of laser pulse energy by debris and slag, improve the material ablation removal efficiency, and thus improve problems such as recast layer, debris deposition, and low processing efficiency. In addition, the high-speed gas flow has a cooling effect on the processing area, which helps to reduce thermal damage from laser processing. At the same time, after the ionized gas flow acts on the processing area, a spatial electric field of about 5kV / cm is formed at the interface between the laser and the material, which constrains the expansion of high-density plasma formed by the phase transition of the material, reduces the shielding and absorption of laser energy by the material plasma, thereby improving the laser energy utilization rate and material removal efficiency. Furthermore, the spatial electric field charges the ablation debris and inhibits its agglomeration and deposition, which can reduce the deposition and adhesion of ablation products on the surface and improve the surface quality of the processed material.

[0067] Laser unit 1 was used to adjust the laser processing parameters to complete single-pulse laser ablation of silicon under different conditions. The atomic force microscopy characterization results of the processed area are as follows: Figures 3a to 3c As shown in the figure, the ablation pits obtained by pure laser and ordinary helium gas-assisted laser processing have a large number of irregular protrusions at the bottom, with surface roughness of 48.3 nm and 34.5 nm, respectively. However, when laser processing is performed with ionized gas flow, the ablation pits are more regular in shape, with no obvious irregular protrusions at the bottom, and the surface roughness is only 9.5 nm. This proves that laser processing with ionized gas flow improves the surface quality and increases the material removal rate.

[0068] In this embodiment, the laser scanning speed is 200 mm / s, and the microgroove morphologies obtained under different auxiliary methods are as follows: Figures 4a to 4c As shown in the figure, pure laser processing results in the shallowest microgroove depth, a distinct recast layer, and significant ablation debris deposition near the microgroove. Gas flow assistance increases the microgroove depth, and slightly improves both the recast layer and debris deposition. Ionized gas flow assistance further increases the microgroove depth, and significantly improves both the recast layer and debris deposition. The material removal volume for the three processing methods is shown in the figure. Figure 5 As shown in the figure, compared with pure laser and airflow-assisted methods, ionization airflow-assisted methods increased the material removal volume by 55% and 11%, respectively.

[0069] In addition, during the actual processing, sensors are set up to provide feedback signals from the processing area to the control unit in real time. The control unit adaptively adjusts the pulse energy of the laser and the ionization gas flow parameters based on the feedback signals to optimize the processing quality. The feedback signals include emission spectrum, temperature field, three-dimensional morphology of the processed surface, roughness, etc.

[0070] Example 3

[0071] This embodiment employs an ionized gas flow-assisted laser micromachining method to fabricate micropores in silicon. The laser 2 generates a focused laser beam 7 with a wavelength of 1030 nm, a pulse width of 300 fs, and a repetition frequency of 100 kHz. The laser power is adjusted to 9.8 W. The gas source 11 for generating the ionized gas flow 13 is high-purity argon gas with a flow rate of 2.0 L / min. After being excited and discharged by a high-frequency AC power supply, it forms an ionized gas flow 13 containing free electrons and charged ions at a velocity of 70 m / s. The angle between the focused laser beam 7 and the ionized gas flow 13 is 45°. Laser processing parameters are adjusted by the control unit 1 to perform silicon surface processing. The multi-pulse ablation threshold of silicon under different processing conditions is calculated. During ionized gas flow-assisted laser processing, high-density free electrons are transported to the laser-material interaction region. These free electrons, acting as seed electrons, promote the development of avalanche ionization, thus accelerating the phase transition and ionization processes after the material absorbs laser energy, thereby achieving material ablation removal at a relatively low laser power.

[0072] When the ionized gas flow acts on the processing area, it forms a high-speed inert gas flow, which can remove ablation products from the processing area, reduce the absorption and shielding of laser pulse energy by debris and slag, improve the material ablation removal efficiency, and thus improve problems such as recast layer, debris deposition, and low processing efficiency. In addition, the high-speed gas flow has a cooling effect on the processing area, which helps to reduce thermal damage from laser processing. At the same time, after the ionized gas flow acts on the processing area, it forms a spatial electric field of 8 kV / cm at the laser-material interface, which constrains the expansion of the high-density plasma formed in the laser-material interaction area, reduces the shielding and absorption of laser energy by the plasma, and thus improves the material removal efficiency. Furthermore, the spatial electric field charges the ablation debris and inhibits its agglomeration and deposition, which can reduce the agglomeration of ablation products and debris deposition, and improve the surface quality of the processed material.

[0073] In addition, during the actual processing, sensors are set up to provide feedback signals from the processing area to the control unit in real time. The control unit adaptively adjusts the pulse energy of the laser and the ionization gas flow parameters based on the feedback signals to optimize the processing quality. The feedback signals include plasma spectrum, backscatter signal and temperature field data.

[0074] In one embodiment, a non-transitory computer-readable storage medium is also provided, on which program instructions for running on a processor are stored. When executed, the program instructions cause the processor to perform the steps of the multiphysics-assisted laser microfabrication method described above, including: controlling laser emission, controlling the discharge timing of the gas ionization device, controlling the positioning and flow rate of the nozzle assembly, and adjusting the parameters according to feedback signals.

[0075] The aforementioned program instructions also include a feedback-based closed-loop control module, which adjusts the laser pulse parameters and ionization gas discharge parameters based on emission spectrum, temperature field, three-dimensional morphology of the processed surface, and roughness data.

[0076] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A multiphysics-assisted laser microfabrication method based on seed electrons, characterized in that, Includes the following steps: An ionized gas flow is introduced into the region where the laser interacts with the material. The ionized gas flow is ionized by high-voltage discharge to form a high-speed gas flow containing free electrons and charged ions. The ionized gas flow provides free electrons in the laser-material interaction region. These free electrons act as seed electrons to promote avalanche ionization after the material absorbs laser energy, thereby accelerating the phase transition and ionization process of the material and reducing the ablation threshold of the material. The high-speed airflow is used to discharge the ablation products from the processing area, while simultaneously cooling the processing area. The ionized gas flow forms a spatial electric field at the interface between the laser and the material to constrain the plasma expansion of the material in the processing area and charge the ablation debris to suppress agglomeration and deposition, thereby improving the quality of the processed surface. The ionized gas flow isolates the laser-material interaction area from direct contact with air, suppressing the oxidation of the processed surface by oxygen and thus improving the surface quality.

2. The multiphysics-assisted laser microfabrication method based on seed electrons according to claim 1, characterized in that, The gas is one or more of nitrogen, helium, or argon.

3. The multiphysics-assisted laser micromachining method based on seed electrons according to claim 1, characterized in that, The ionized gas flow rate is 0.5–100 m / s to balance debris removal and cooling effect.

4. The multiphysics-assisted laser micromachining method based on seed electrons according to claim 1, characterized in that, The ionized gas flow is directed through the nozzle assembly to the laser-material interaction region to ensure efficient injection of free electrons; the angle between the nozzle assembly and the laser beam propagation direction is 0°–90°.

5. The multiphysics-assisted laser micromachining method based on seed electrons according to claim 1, characterized in that, The spatial electric field strength is in the range of 0.1–20 kV / cm to ensure effective confinement of the high-density plasma expansion formed by material phase transition.

6. The multiphysics-assisted laser micromachining method based on seed electrons according to claim 1, characterized in that, This method is applied to microstructure processing, thin film peeling, or material surface modification. Microstructures include micropores, trenches, and micropits.

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