High-temperature-resistant waveguide electrode coating protection structure

Abstract

The present application relates to the technical field of high-power gas laser, in particular to a high-temperature-resistant waveguide electrode coating protection structure, which comprises a buffer heat dissipation layer, an intelligent sensing layer and an insulating functional coating layer arranged on the surface of the waveguide electrode substrate in sequence. A three-dimensional interlocking interface structure is arranged at the joint interface between the waveguide electrode substrate and the buffer heat dissipation layer. The intelligent sensing layer is a patterned transparent conductive oxide film, which is electrically connected with an external monitoring circuit and used for real-time monitoring of the temperature and interlayer insulation state of the protection structure. A high-emissivity radiation heat dissipation layer is further coated on the outer surface of the insulating functional coating layer. The present application greatly improves the adhesion of the coating layer through the three-dimensional interlocking interface structure, significantly reduces the working temperature through the "conduction + radiation" dual-path heat dissipation system, and realizes online monitoring and early warning of the health state of the protection structure through the intelligent sensing layer, effectively solving the problems of easy peeling of the coating layer, insufficient heat dissipation and inability to monitor online in the prior art.

Description

Technical Field

[0001] This invention relates to the field of high-power gas laser technology, specifically to a high-temperature resistant waveguide electrode coating protection structure. Background Technology

[0002] In high-power gas lasers (such as RF-excited CO2 lasers), to suppress higher-order waveguide modes and preferentially obtain the lowest-order mode (such as EH), 11 To improve beam quality, existing technology has developed a method of coating a specific area on the surface of a waveguide electrode with an insulating film. This method does not damage the electrode substrate and uses the insulating material to change the local conductivity of the electrode surface, forming a "quasi-free space region" with a weakened electric field, thereby effectively realizing the mode selection function. This method successfully avoids the disadvantages of traditional physical recessed structures (such as Chinese patent CN102136671B), such as high processing difficulty, damage to electrode integrity, and the tendency of concentrated electric field at the edges to induce partial discharge.

[0003] However, the long-term reliability of this type of insulating coating still faces serious challenges in harsh environments with high temperature, strong electric field, and corrosive discharge gas, specifically in the following three aspects:

[0004] First, insufficient interfacial adhesion leads to coating peeling. There is a significant difference in the coefficient of thermal expansion between insulating functional coatings (such as aluminum nitride AlN, zirconium oxide ZrO2) and electrode substrates typically made of copper (copper approximately 17 × 10⁻⁶). -6 / K, AlN approximately 4.5×10 -6 / K). Under frequent laser start-up and shutdown, and periodic high and low temperature shocks (such as -40℃ to +150℃), cyclic thermal stress will be generated at the planar interface between the coating and the substrate. Over time, this will lead to coating delamination, peeling, or even large-area detachment, ultimately causing the mode selection function to be completely lost.

[0005] Secondly, the single heat dissipation path leads to temperature accumulation. Existing protective structures typically rely solely on heat conduction to diffuse heat from the coating towards the electrode substrate. Laser resonant cavities are often located in vacuum or low-pressure working gas environments, resulting in extremely low convective heat transfer efficiency. A single conduction path is insufficient to dissipate the accumulated heat on the surface in a timely manner, leading to localized hot spots in the coating. Prolonged exposure to high temperatures accelerates the aging and performance degradation of the insulating materials, and may even trigger thermal breakdown.

[0006] Third, there is a lack of online status awareness and early warning capabilities. Existing coating protection structures are all passive protection devices, lacking inherent status awareness functions. They cannot provide early warnings during early stages of failure, such as localized micro-breakdowns in the coating, abnormal temperature rises, or micro-cracks caused by material fatigue. Maintenance personnel can only conduct post-incident inspections after significant degradation in macroscopic performance such as laser output power and mode quality. This "only when it breaks down" approach results in high maintenance costs and time consumption, and the failure to address minor faults promptly can induce larger cascading damage, severely impacting the availability of high-value laser systems. Summary of the Invention

[0007] The purpose of this invention is to provide a high-temperature resistant waveguide electrode coating protection structure to solve the problems mentioned in the background art, such as easy peeling, insufficient heat dissipation, and inability to monitor its own working health status online in high-temperature and strong electric field working environments.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant waveguide electrode coating protection structure, comprising a buffer heat dissipation layer, an intelligent sensing layer, and an insulating functional coating layer sequentially disposed on the surface of the waveguide electrode substrate;

[0009] A three-dimensional interlocking interface structure is provided at the interface between the waveguide electrode substrate and the buffer heat dissipation layer; the smart sensing layer is a patterned transparent conductive oxide film, which is electrically connected to an external monitoring circuit for real-time monitoring of the temperature and interlayer insulation status of the protective structure; a high emissivity radiation heat dissipation layer is also covered on the outer surface of the insulating functional coating away from the smart sensing layer, and the emissivity of the high emissivity radiation heat dissipation layer for infrared electromagnetic waves in the 3-12μm band is greater than 0.8.

[0010] Preferably, the three-dimensional interlocking interface structure is an arrayed micro-nano anchoring structure pre-processed on the surface of the waveguide electrode substrate through a material removal process. The material entity of the buffer heat dissipation layer fills and embeds itself inside the micro-nano anchoring structure to form a three-dimensional mechanical interlock.

[0011] Preferably, the arrayed micro-nano anchoring structure is an inverted conical micropore array with a pore diameter of 5-50 μm and a depth of 10-80 μm, and the diameter at the micropore opening is smaller than the bottom diameter, forming a mechanical locking form.

[0012] Preferably, the arrayed micro-nano anchoring structure is a grid-like groove with a width of 10-100μm and a depth of 20-60μm. Its cross-sectional shape is dovetail or trapezoidal, forming a mechanical locking form.

[0013] Preferably, the material of the buffer heat dissipation layer is aluminum nitride (AlN), beryllium oxide (BeO) or diamond film, with a thermal conductivity greater than 100 W / (m·K), a coefficient of thermal expansion between that of the waveguide electrode substrate and the insulating functional coating, and a thickness of 20-100 μm.

[0014] Preferably, the smart sensing layer is a patterned indium tin oxide (ITO) or aluminum-doped zinc oxide (AZO) transparent conductive film with a thickness of 50-500 nm, and its pattern includes a serpentine resistance pattern for monitoring temperature and an interdigitated capacitance pattern for monitoring interlayer breakdown.

[0015] Preferably, the interdigitated capacitor pattern has a finger spacing of less than 50μm, and under normal conditions it is in a high resistance or open circuit state. When insulation breakdown occurs, the leakage current causes a sudden change in resistance, and an early warning signal is output.

[0016] Preferably, the insulating functional coating covers the region of the waveguide electrode corresponding to the beam waist of the resonant cavity, and its material is aluminum nitride, zirconium oxide or polyimide, with a thickness of 50-200 μm in the central region and a gradient transition structure with the thickness gradually decreasing to zero at its surrounding edges.

[0017] Preferably, the high emissivity radiative heat dissipation layer is made of erbium oxide (Er2O3) or silicon carbide (SiC), with a thickness of 5-30 μm, an emissivity greater than 0.85 for infrared electromagnetic waves in the 3-12 μm band, and a coverage area of ​​not less than 80% of the area of ​​the insulating functional coating.

[0018] Preferably, a dense protective layer is fully covered on the outer surface of the high emissivity radiation heat dissipation layer and all exposed areas of the sidewalls. The dense protective layer is a silicon dioxide (SiO2) or aluminum oxide (Al2O3) film with a thickness of 10-50 nm, which is used to physically isolate the discharge gas from erosion of the functional layers below.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] First, the interfacial bonding strength is increased by orders of magnitude, fundamentally solving the problem of high-temperature peeling. This invention upgrades the traditional two-dimensional surface bonding between the coating and the substrate, which relies solely on van der Waals forces and chemical bonds, to a three-dimensional bonding containing countless micro- and nano-anchor structures by constructing a three-dimensional interlocking interface structure. The mechanical interlocking formed by inverted conical micropores or dovetail grooves ensures that the protective structure resists peeling not only through intermolecular forces but also through the inherent resistance of the structure itself when subjected to thermal cycling shear stress. Compared to traditional planar coatings, adhesion can be increased several times, and the structure can maintain its integrity even under frequent and severe temperature shocks, ensuring the long-term effectiveness of the mode selection function.

[0021] Secondly, a dual-path heat dissipation system combining conduction and radiation was constructed, significantly reducing the operating temperature and delaying material aging. This invention not only retains the efficient lateral conduction heat dissipation path of the buffer heat dissipation layer but also opens up a highly efficient second path for direct radiative heat dissipation to the space environment by adding a high-emissivity radiative heat dissipation layer to the surface. This path is particularly crucial for laser electrodes in vacuum or low-pressure gas environments, overcoming the bottleneck of heat dissipation solely through conduction. The synergistic effect of the dual paths effectively reduces the overall steady-state operating temperature of the protective structure, thereby exponentially delaying the aging rate and performance degradation of the insulating material.

[0022] Third, this invention endows the passive protection structure with active online intelligent sensing capabilities, achieving a leap from "reactive maintenance" to "predictive maintenance." Through an integrated intelligent sensing layer, this invention enables the coated protection structure to monitor and issue early warnings in real time for its core health parameters, such as temperature and insulation status. When abnormal temperature rises, localized micro-breakdowns, or fatigue cracks appear in the coating, the monitoring circuit can immediately detect the corresponding changes in the resistance or capacitance of the sensing layer, issuing an early warning before the macroscopic performance of the laser deteriorates. This not only provides maintenance personnel with a precise preventative replacement window, avoiding unplanned downtime, but also accurately indicates the location of the fault, significantly reducing the life-cycle maintenance costs and operational risks of high-value laser systems. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0024] Figure 2 This is a schematic diagram of the cross-sectional layered structure of the present invention;

[0025] Figure 3 This is an enlarged view of the locking morphology of the inverted conical micro-hole in the three-dimensional interlocking interface structure of the present invention;

[0026] Figure 4 This is a top view schematic diagram of the micro-nano pattern layout of the intelligent sensing layer of the present invention;

[0027] Figure 5 This is a curve comparing the adhesion retention rate of the protective structure of this invention with that of existing conventional planar coating structures in a thermal cycling aging test.

[0028] In the figure: 10, waveguide electrode substrate; 11, three-dimensional interlocking interface structure; 11a, inverted conical micropore; 20, buffer heat dissipation layer; 30, intelligent sensing layer; 31, temperature sensing area; 32, breakdown warning area; 33, lead-out electrode; 40, insulating functional coating; 41, gradient transition structure; 50, high emissivity radiation heat dissipation layer; 60, dense protective layer. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] The present invention provides a high-temperature resistant waveguide electrode coating protection structure as follows: Figure 1 As shown, it includes a waveguide electrode substrate 10, on which a buffer heat dissipation layer 20, a smart sensing layer 30 and an insulating functional coating layer 40 are sequentially disposed.

[0031] Furthermore, such as Figure 2 and Figure 3 As shown, at the interface between the waveguide electrode substrate 10 and the buffer heat dissipation layer 20, an array of inverted conical micropores 11a or dovetail-shaped grooves are pre-formed by laser processing or etching to form a three-dimensional interlocking interface structure 11. Subsequently, the buffer heat dissipation layer 20 is deposited, and its material solid fills and embeds into the above-mentioned micro-nano anchoring structure to form a three-dimensional mechanical interlock.

[0032] Furthermore, such as Figure 4 As shown, a patterned indium tin oxide (ITO) thin film with a thickness of 50-500 nm is fabricated on the buffer heat dissipation layer 20 using a magnetron sputtering process as the smart sensing layer 30. The pattern of this layer includes a serpentine resistor pattern (temperature sensing region 31) for monitoring temperature and an interdigital capacitor pattern (breakdown warning region 32) for monitoring interlayer breakdown, and is electrically connected to an external monitoring circuit through lead-out electrodes 33.

[0033] Furthermore, an insulating functional coating 40, made of aluminum nitride, is prepared on the smart sensing layer 30 using plasma spraying or chemical vapor deposition. The coating has a thickness of 50-200 μm in the central region and a gradient transition structure 41 with a thickness gradually decreasing to zero around its perimeter. The insulating functional coating 40 covers the region of the waveguide electrode corresponding to the beam waist of the resonant cavity.

[0034] Furthermore, on the outer surface of the insulating functional coating 40, a high emissivity radiation heat dissipation layer 50 is further covered, which is made of erbium oxide (Er2O3) or silicon carbide (SiC), with a thickness of 5-30μm, an emissivity of greater than 0.85 for infrared electromagnetic waves in the 3-12μm band, and a coverage area of ​​not less than 80% of the area of ​​the insulating functional coating.

[0035] Furthermore, a dense protective layer 60 is fully covered on the outer surface of the high emissivity radiative heat dissipation layer 50 and all exposed sidewall areas. The material is silicon dioxide (SiO2) or aluminum oxide (Al2O3), with a thickness of 10-50nm, to physically isolate the discharge gas from eroding the functional layers below.

[0036] Example 1

[0037] This invention provides a fabrication process for a waveguide electrode coating protection structure in this embodiment, specifically including the following steps: Step 1: Fabricating a three-dimensional interlocking interface structure, such as... Figure 3 As shown in the enlarged view, on the clean surface of the copper waveguide electrode substrate 10, corresponding to the beam waist region of the resonant cavity, an array of inverted conical micro-holes 11a are precisely fabricated using femtosecond laser etching, thereby forming a three-dimensional interlocking interface structure 11. In this embodiment, the diameter of a single micro-hole is approximately 20 μm, and the depth is approximately 40 μm. The diameter at the opening of the micro-hole is slightly smaller than the diameter at the bottom, forming a classic mechanical locking shape with a larger inner diameter and a smaller outer diameter. The center-to-center distance between adjacent micro-holes is 50 μm, arranged in a hexagonal close-packed array to maximize the anchoring density.

[0038] Step 2: Deposit a buffer heat dissipation layer. Using magnetron sputtering, a 60 μm thick high-purity aluminum nitride (AlN) film is deposited on the surface of the substrate with the three-dimensional interlocked interface structure 11 as a buffer heat dissipation layer 20. The thermal conductivity of aluminum nitride is approximately 180 W / (m·K), far exceeding the design requirement of 100 W / (m·K); its coefficient of thermal expansion is approximately 4.5 × 10⁻⁶. -6 / K, which is exactly between the copper substrate (approximately 17×10). -6 The AlN material acts as a gradient transition between the sputtered particles and the subsequent insulating layer material. Under the high kinetic energy of the sputtered particles, the AlN material fully fills and densely embeds itself into each inverted conical micropore 11a, forming a seamless, robust three-dimensional mechanically interlocked interface.

[0039] Step 3: Fabrication of the smart sensing layer. On the smooth upper surface of the buffer heat dissipation layer 20, a 200nm thick indium tin oxide (ITO) transparent conductive film is deposited and patterned using a lift-off process to form the smart sensing layer 30. For example... Figure 4As shown, through micro-nano pattern design, this layer is divided into two functional areas: a temperature sensing area 31 with a serpentine wiring layout, a linewidth of 20 μm, and a total length of approximately 50 mm, which utilizes the positive temperature coefficient (TCR≈-0.02% / ℃) characteristic of ITO resistance increasing with temperature to accurately monitor local temperature; and an interdigitated capacitor-type breakdown warning area 32 with a finger spacing of 30 μm and a finger length of 2 mm, used to generate a momentary resistance change signal due to leakage current flow when the upper insulation breaks down. Both areas are connected to an external impedance analysis and monitoring circuit through ITO lead-out electrodes 33.

[0040] Step 4: Depositing the insulating functional coating and gradient transition. On top of the area covered by the smart sensing layer 30, a reactive magnetron sputtering process is used to deposit an aluminum nitride layer with a central region thickness of 100 μm, serving as the insulating functional coating 40. Its coverage length is precisely controlled to 5 mm using a mask, corresponding to 0.5 times the Rayleigh length of the resonant cavity. During deposition, a 3 mm wide, approximately 10-degree angled straight slope with the electrode surface is created using a shielding fixture with a specific gradient at the edge region; this is the gradient transition structure 41, used to eliminate electric field concentration at the coating edge.

[0041] Step 5: Fabrication of a high-emissivity heat dissipation layer. A 15 μm thick erbium oxide (Er₂O₃) thin film is deposited on the outer surface of the insulating functional coating 40 using electron beam evaporation, serving as the high-emissivity heat dissipation layer 50. This layer covers approximately 95% of the upper surface area of ​​the insulating functional coating, exceeding the 80% requirement. Infrared spectroscopy testing shows that this material exhibits a normal infrared emissivity of up to 0.9 in the 3-12 μm wavelength band corresponding to the laser's operating temperature, enabling efficient dissipation of accumulated heat into the cavity space via electromagnetic radiation.

[0042] Step Six: Deposit a dense protective layer. Using atomic layer deposition (ALD) technology, all the structures formed above are placed into the deposition chamber, and a dense alumina (Al2O3) film with a thickness of 30 nm is conformally grown on the entire surface as a dense protective layer 60. This layer is dense and free of pinholes, which can effectively physically isolate the internal functional layers from long-term chemical erosion by discharge plasmas such as CO2, N2, and He, while maintaining high transmittance for infrared radiation and not affecting the function of the underlying radiative heat dissipation layer.

[0043] Example 2

[0044] This embodiment is basically the same as Embodiment 1, except for the form of the three-dimensional interlocking interface structure and the material selection of the buffer heat dissipation layer.

[0045] In this embodiment, the three-dimensional interlocking interface structure 11 adopts a grid-like trench form. Orthogonal grid trenches are fabricated on the surface of the copper waveguide electrode substrate 10 by ultraviolet laser etching. The trenches are 50 μm wide and 40 μm deep, with a dovetail-shaped cross-section (i.e., the width at the opening is smaller than the width at the bottom), forming a mechanical locking mechanism. The buffer heat dissipation layer 20 is made of beryllium oxide (BeO) material, prepared by chemical vapor deposition (CVD), and has a thickness of 50 μm. BeO has a high thermal conductivity of 260 W / (m·K) and a coefficient of thermal expansion of approximately 8 × 10⁻⁶. -2 / K, also positioned between the copper substrate and the insulating plating, is deposited with beryllium oxide material that fully fills the dovetail trenches, forming a robust three-dimensional mechanically interlocking interface similar to that in Example 1. The materials, structural parameters, and fabrication processes of the remaining layers are consistent with those in Example 1.

[0046] Comparative Example

[0047] To verify the technical effects of this invention, a comparative example is provided as a reference. The comparative example employs a traditional planar plating structure: on the surface of a copper waveguide electrode substrate, without any surface treatment (no three-dimensional interlocking interface structure), a buffer heat dissipation layer and an insulating functional plating layer of the same material and thickness as in Example 1 are directly deposited sequentially, without the intelligent sensing layer, high emissivity radiation heat dissipation layer, and dense protective layer. In short, the comparative example only includes a planar combined buffer layer and insulating layer, representing a typical solution in the prior art.

[0048] For performance comparison and verification, the samples prepared in Example 1 and the comparative sample were subjected to the following reliability comparison tests:

[0049] I. Thermal Cycling Shock Test (Adhesion Retention Rate): Test conditions: temperature range -40℃ to +150℃, heating / cooling rate 20℃ / min, holding at both high and low temperatures for 15 minutes, 1000 cycles. After every 200 cycles, the coating adhesion is tested using the cross-cut adhesion test (refer to GB / T9286), and the adhesion retention rate is calculated. Test results are as follows: Figure 5 As shown: The coating adhesion of the sample in Example 1 maintained more than 92% of its initial value after 1000 cycles, with a gradual decrease in the curve; while the adhesion of the comparative sample decreased rapidly with the number of cycles, reaching less than 40% of the initial value after 1000 cycles. The comparison shows that the three-dimensional interlocking interface structure improved the adhesion by more than 2.3 times, fundamentally solving the problem of high-temperature peeling.

[0050] II. Steady-state operating temperature test. Test conditions: Under full-power operation of the RF-excited CO2 laser, the steady-state surface temperature of the coating in Example 1 and the control sample without a high-emissivity radiative heat dissipation layer (the rest of the structure is the same as in Example 1) was measured using an infrared thermal imager. Test results: The steady-state surface temperature of the coating in Example 1 was 145℃, while that of the control sample without a radiative heat dissipation layer was 160℃, a temperature reduction of 15℃. This verifies that the "radiative heat dissipation" second path constructed by the high-emissivity radiative heat dissipation layer can significantly reduce the operating temperature and delay material aging.

[0051] III. Functional Verification of the Intelligent Sensing Layer. Test Conditions: Online functional testing was conducted on the intelligent sensing layer of Example 1, including temperature monitoring accuracy testing and breakdown warning response testing. Test Results: The temperature measurement accuracy of the temperature sensing area was better than ±1℃ (compared to thermocouple calibration within the range of 25℃ to 200℃). In the breakdown warning test, a simulated overvoltage signal was applied to introduce a micro-breakdown in the upper insulation layer. The monitoring circuit captured the resistance change signal of the interdigitated capacitor area within 100 milliseconds after the breakdown occurred and output an alarm. This verified the feasibility and rapid response capability of online sensing and warning.

[0052] Working principle: After the user installs this protective structure, during laser operation, heat is conducted to the electrode substrate through the buffer heat dissipation layer 20, and simultaneously dissipated outwards through the high emissivity radiation heat dissipation layer 50, achieving dual-path cooling. The intelligent sensing layer 30 monitors the coating temperature and insulation status in real time. If abnormal temperature rise, microcracks, or breakdown occur in the coating, the monitoring circuit will detect sudden changes in resistance or capacitance and issue an early warning signal. The adhesion retention rate comparison curve is shown below. Figure 5 As shown, compared with traditional planar coatings, the present invention exhibits significantly better adhesion retention in thermal cycling aging tests.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-temperature resistant waveguide electrode coating protection structure, comprising a buffer heat dissipation layer, an intelligent sensing layer, and an insulating functional coating layer sequentially disposed on the surface of a waveguide electrode substrate, characterized in that: A three-dimensional interlocking interface structure is provided at the interface between the waveguide electrode substrate and the buffer heat dissipation layer; the smart sensing layer is a patterned transparent conductive oxide film, which is electrically connected to an external monitoring circuit for real-time monitoring of the temperature and interlayer insulation status of the protective structure; a high emissivity radiation heat dissipation layer is also covered on the outer surface of the insulating functional coating away from the smart sensing layer, and the emissivity of the high emissivity radiation heat dissipation layer for infrared electromagnetic waves in the 3-12μm band is greater than 0.

8.

2. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The three-dimensional interlocking interface structure is an arrayed micro-nano anchoring structure pre-processed on the surface of the waveguide electrode substrate through a material removal process. The material entity of the buffer heat dissipation layer fills and embeds itself inside the micro-nano anchoring structure to form a three-dimensional mechanical interlock.

3. The high-temperature resistant waveguide electrode coating protection structure according to claim 2, characterized in that: The arrayed micro-nano anchoring structure is an inverted conical micropore array with a pore diameter of 5-50 μm and a depth of 10-80 μm. The diameter at the opening of the micropore is smaller than the diameter at the bottom, forming a mechanical locking shape.

4. The high-temperature resistant waveguide electrode coating protection structure according to claim 2, characterized in that: The arrayed micro-nano anchoring structure consists of grid-like grooves with a width of 10-100μm and a depth of 20-60μm. Its cross-sectional shape is dovetail or trapezoidal, forming a mechanical locking mechanism.

5. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The material of the buffer heat dissipation layer is any one of aluminum nitride (AlN), beryllium oxide (BeO) or diamond film, with a thermal conductivity greater than 100 W / (m·K), a coefficient of thermal expansion between that of the waveguide electrode substrate and the insulating functional coating, and a thickness of 20-100 μm.

6. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The smart sensing layer is a patterned indium tin oxide (ITO) or aluminum-doped zinc oxide (AZO) transparent conductive film with a thickness of 50-500nm. Its pattern includes a serpentine resistor pattern for monitoring temperature and an interdigitated capacitor pattern for monitoring interlayer breakdown.

7. The high-temperature resistant waveguide electrode coating protection structure according to claim 6, characterized in that: The interdigitated capacitor pattern has a finger spacing of less than 50μm. Under normal circumstances, it is in a high-resistance or open-circuit state. When insulation breakdown occurs, the resistance changes suddenly due to leakage current, and a warning signal is output.

8. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The insulating functional coating covers the region of the waveguide electrode corresponding to the beam waist of the resonant cavity. It is made of any one of aluminum nitride, zirconium oxide or polyimide, with a thickness of 50-200 μm in the central region and a gradient transition structure with the thickness gradually decreasing to zero around its perimeter.

9. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The high emissivity radiative heat dissipation layer is made of erbium oxide (Er2O3) or silicon carbide (SiC), with a thickness of 5-30μm, an emissivity greater than 0.85 for infrared electromagnetic waves in the 3-12μm band, and a coverage area of ​​not less than 80% of the area of ​​the insulating functional coating.

10. The high-temperature resistant waveguide electrode coating protection structure according to claim 1, characterized in that: The outer surface of the high emissivity radiation heat dissipation layer and all exposed sidewall areas are covered with a dense protective layer. The dense protective layer is a silicon dioxide (SiO2) or aluminum oxide (Al2O3) film with a thickness of 10-50 nm, which is used to physically isolate the discharge gas from eroding the functional layers below.

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