Phase-change circulating heat dissipation device for slow wave structure of traveling wave tube and traveling wave tube comprising phase-change circulating heat dissipation device

Abstract

The invention discloses a phase change circulation heat dissipation device for a slow wave structure of a traveling wave tube and the traveling wave tube comprising the same, and relates to the technical field of microwave vacuum electronics, the heat dissipation device comprises an internal heat absorption unit integrated on a slow wave structure body base material, an external cooling unit arranged outside the traveling wave tube and a sealed circulation pipeline connecting the internal heat absorption unit and the external cooling unit, the three parts form a closed loop which is filled with a working medium. During working, the micro-scale flow channel of the internal heat absorption unit directly absorbs heat of the slow-wave structure, so that a working medium is vaporized; the steam flows to an external cooling unit for condensation and heat release under the action of pressure difference; condensate is driven by gravity and capillary force to flow back to the interior, and self-sustaining circulation is formed. Efficient heat dissipation under extremely high heat flux is achieved through phase change latent heat, the vacuum compatibility problem is thoroughly solved through closed independent circulation, the structure is compact, external strong driving force is not needed, the working stability of the traveling wave tube is remarkably improved, and the service life of the traveling wave tube is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology, and in particular to a phase-change circulating heat dissipation device for a traveling wave tube slow-wave structure and a traveling wave tube comprising the same. Background Technology

[0002] As a core microwave vacuum electronic device, the stability and lifespan of a traveling wave tube (TWT) largely depend on its heat dissipation efficiency. Especially in the terahertz band, the size of the core component of the TWT—the folded waveguide slow-wave structure—has been shrunk to sub-millimeter or even micrometer scale. During operation, electron beam interception and high-frequency losses generate extremely high local heat flux densities within this microscale structure. If the heat cannot be dissipated in time, it will lead to excessive temperature rise, causing material performance degradation, increased thermal stress, and focusing magnetic field drift, ultimately resulting in performance deterioration or even failure of the TWT.

[0003] Among the technical solutions known to the inventor, the heat dissipation solutions for this slow-wave structure are mainly divided into two categories. The first category is external conduction cooling, which involves connecting the slow-wave structure to external heat sinks, base plates, and cold plates through multi-layer welding, ultimately conducting heat to the external environment. This method has inherent defects such as long heat conduction paths, high contact thermal resistance, and limited thermal conductivity of interface materials, resulting in a bottleneck in heat dissipation capacity and making it difficult to meet the high heat dissipation requirements of continuous wave operation of terahertz traveling wave tubes.

[0004] The second approach integrates liquid-cooled channels within the slow-wave structure, directly removing heat through single-phase forced convection of the coolant. While this method significantly improves heat dissipation efficiency compared to external conductive cooling, it still has limitations: First, driving liquid flow within microscale channels requires an external pump to provide a high pressure head, increasing system complexity and power consumption; second, the heat transfer capacity of single-phase convection cooling is limited by the specific heat capacity of the coolant, and there is still room for improvement in temperature rise control when facing extremely high heat flux densities.

[0005] Therefore, there is an urgent need for a new heat dissipation solution that is more efficient in heat dissipation and better able to adapt to extremely high heat flux density at the microscale. Summary of the Invention

[0006] The purpose of this invention is to provide a phase change cycle heat dissipation device for a traveling wave tube slow wave structure and a traveling wave tube containing the same, so as to solve the problems existing in the prior art, thereby achieving higher heat dissipation efficiency and better adaptability to extremely high heat flux density at the microscale.

[0007] To achieve the above objectives, the present invention provides the following solution: A phase-change circulating heat dissipation device for a traveling wave tube slow-wave structure includes: The internal heat absorption unit, the external cooling unit, and the sealed circulation pipeline connecting the two constitute a closed loop for the working fluid circulation. The internal heat absorption unit is a microscale flow channel network integrated in the slow wave structure substrate, which is used to directly contact and absorb the heat generated when the slow wave structure is working. The external cooling unit is located outside the traveling wave tube and is used to dissipate the heat carried by the working fluid to the external environment. The closed loop is filled with a working fluid. After absorbing heat at the internal heat-absorbing unit, the working fluid undergoes a phase change from liquid to gas, forming a vapor flow. Under the action of pressure difference, the vapor flow flows to the external cooling unit through the sealed circulation pipeline. After releasing heat at the external cooling unit, the vapor flow condenses into a liquid. The condensed liquid working fluid flows back to the internal heat-absorbing unit through the sealed circulation pipeline under the drive of gravity, capillary force, or pressure difference, completing the cycle.

[0008] In an exemplary embodiment, the external cooling unit is a liquid-cooled plate heat exchanger, which is provided with a secondary cooling fluid channel for exchanging heat with the working fluid vapor or condensate from the internal heat-absorbing unit through the secondary cooling fluid, and finally exporting the heat.

[0009] In one exemplary embodiment, the external cooling unit is a finned air-cooled condenser that condenses the working fluid vapor flowing through it and releases heat through forced air cooling or natural convection.

[0010] In one exemplary embodiment, the microscale flow channel network of the internal heat absorption unit is directly embedded in or surrounds the high heat flux density region in the slow-wave structure where the electron beam channel interacts with the slow-wave structure.

[0011] In one exemplary embodiment, the sealed circulation pipeline is integrated with the electromagnetic wave input and output terminals of the slow wave structure to avoid introducing additional connecting components and ensure structural compactness.

[0012] In one exemplary embodiment, the working fluid is deionized water.

[0013] In one exemplary embodiment, the inner wall of the microscale flow channel of the internal heat absorption unit is processed with microstructures, which are used to enhance the heat exchange efficiency of the working fluid and provide capillary force to drive the liquid working fluid backflow.

[0014] In one exemplary embodiment, the microstructure is a parallel fin array extending along the flow channel direction.

[0015] In one exemplary embodiment, the closed loop is evacuated before encapsulation, so that the inside of the loop maintains a negative pressure or a specific working fluid saturated vapor pressure environment after the working fluid is injected.

[0016] The present invention also provides a traveling wave tube, including the above-described slow-wave structure heat dissipation device.

[0017] The present invention achieves the following technical effects compared to the prior art: 1. Achieved ultra-high efficiency heat dissipation at the source: By directly integrating internal heat-absorbing units into the heat source of the slow-wave structure in the form of a microscale flow channel network, and combining the phase change (vaporization) heat absorption principle of the working fluid, heat exchange is carried out using the latent heat of vaporization of the working fluid. The latent heat of phase change is much higher than the sensible heat of the liquid, enabling this scheme to carry away a large amount of heat with extremely small flow rates and temperature differences, achieving precise and efficient cooling of microscale high heat flux density regions, fundamentally suppressing the core temperature rise of the slow-wave structure.

[0018] 2. A self-circulating system with low drive requirements was constructed: The system utilizes the pressure difference generated by vaporization in the endothermic zone as the main driving force for steam flow to the cooling unit, and utilizes gravity and the possible capillary force of the microchannels as the main driving force for condensate return. This self-driven or low external power drive characteristic based on the thermodynamic phase change process reduces the dependence on high-power external circulation pumps, simplifies the system structure, and improves its applicability and reliability in compact spaces.

[0019] 3. Improved system thermal load handling capability and reliability: The phase change heat transfer mechanism is sensitive to changes in heat flow and can quickly respond to fluctuations in the heat dissipation of the slow-wave structure. The closed-loop system avoids the consumption and contamination of the working fluid, ensuring long-term stable system operation. The significantly reduced operating temperature and temperature gradient of the slow-wave structure effectively reduce thermal stress and thermal fatigue, thereby improving the overall service life and reliability of the traveling wave tube. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a phase change circulating heat dissipation device for a traveling wave tube slow wave structure, as disclosed in a specific embodiment of the present invention. Figure 2 A schematic diagram of a liquid-cooled plate heat exchanger used for the external cooling unit; Figure 3 A schematic diagram of a structure using an air-cooled condenser for the external cooling unit; Figure 4 for Figure 2 A partially enlarged view of the AA-axis cross-sectional view, used to show the microstructure in the internal heat absorption unit; The components include: 1. Internal heat absorption unit; 2. External cooling unit; 3. Sealed circulation pipeline; 4. Liquid-cooled plate heat exchanger; 5. Air-cooled condenser; 6. Electron injection channel; 7. Slow wave structure; 8. Input end; 9. Output end; 10. Microstructure. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The purpose of this invention is to provide a phase change cycle heat dissipation device for a traveling wave tube slow wave structure and a traveling wave tube containing the same, so as to solve the problems existing in the prior art, thereby making the heat dissipation efficiency higher and more adaptable to microscale extremely high heat flux density.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1 Please refer to Figures 1 to 4 This embodiment provides a phase change circulating heat dissipation device for a traveling wave tube slow-wave structure, mainly comprising three core parts: an internal heat absorption unit 1, an external cooling unit 2, and a sealed circulating pipeline 3 connecting the two, which together form a closed loop in which the working fluid can circulate. After assembly, the loop is evacuated to a vacuum and injected with an appropriate amount of working fluid, such as deionized water, thereby forming a closed environment with negative pressure and containing liquid working fluid in the initial state.

[0026] Its working principle is a dynamic thermodynamic cycle. When the traveling wave tube is working, the slow-wave structure 7 generates a large amount of heat. This heat is rapidly captured by the internal heat-absorbing unit 1, which is closely integrated with it. The liquid working fluid in the microscale flow channel network within the unit boils upon heating, changing from a liquid phase to a gas phase. This phase change process absorbs a large amount of latent heat of vaporization, thus efficiently converting the heat of the slow-wave structure 7 into the internal energy of the working fluid. Driven by the increase in local pressure, the generated steam flows through the sealed circulation pipe 3 to the external cooling unit 2 located outside the traveling wave tube cavity. In the external cooling unit 2, the steam exchanges heat with an external cold source such as secondary cooling water or forced air flow, releasing latent heat of vaporization and condensing back into a liquid. The condensed liquid working fluid, driven by gravity, the pressure difference generated by the possible inclined arrangement of the return pipe, and the capillary force that the microchannels of the internal heat-absorbing unit 1 may possess, naturally flows back to the internal heat-absorbing unit 1 through the sealed circulation pipe 3, completing a complete automatic cycle of heat absorption-phase change-condensation-return.

[0027] In the technical solution of this embodiment, "microscale" mainly refers to the hydraulic diameter or characteristic size of the fluid channel being less than 1 millimeter, and usually ranging from tens of micrometers (μm) to hundreds of micrometers.

[0028] This scope is defined primarily based on the following two points: Physical basis: At this scale, the surface tension and capillary effect of the fluid become significant, which is the key physical basis for achieving the "recirculation under capillary force" described in this embodiment. The smaller the channel size, the stronger the capillary driving force is generally.

[0029] Engineering implementation and functional matching: It is small enough to be directly integrated into the sub-millimeter-scale terahertz folded waveguide slow wave structure without destroying its core electromagnetic functional structure.

[0030] It is large enough that it is feasible and reliable to manufacture using conventional precision machining techniques such as micro-milling, wire cutting, and laser processing.

[0031] It can meet the huge specific surface area (heat transfer area per unit volume) required to dissipate heat from the extremely high local heat flux density of slow-wave structures.

[0032] The beneficial effects of this embodiment are as follows: First, by utilizing the latent heat of phase change of the working fluid for heat exchange, the heat carrying capacity per unit mass of the working fluid far exceeds that of single-phase convective cooling relying solely on temperature increases. This is particularly suitable for operating conditions where the local heat flux density of the slow-wave structure 7 is extremely high, achieving efficient cooling at the "source." Second, the circulation power mainly comes from the pressure difference generated by the heat input itself and natural forces, reducing reliance on complex external mechanical pumps, simplifying the system, and improving reliability.

[0033] Based on the above system architecture, the specific form of the external cooling unit 2 can be flexibly configured according to the application scenario. As a preferred embodiment, the external cooling unit 2 is implemented as a liquid-cooled plate heat exchanger 4. This heat exchanger has independent secondary cooling fluid channels internally. The high-temperature working fluid vapor flowing out from the internal heat absorption unit 1 condenses on the outer wall of this channel or within the interwoven channels. The heat released is transferred through the partition wall to the cooling water or other coolant that is forcibly circulated in the secondary channels, and finally dissipated to the environment by an external cooling tower or chiller. This solution has high heat dissipation power and strong heat load capacity, making it suitable for traveling wave tube systems with high output power and severe heat loads.

[0034] As another preferred embodiment, the external cooling unit 2 is implemented as a finned air-cooled condenser 5. High-temperature steam flows through the finned tubes of the condenser, and the heat is directly dissipated to the surrounding air through forced convection driven by a fan or, in some low-power scenarios, through natural convection. This solution eliminates the need for a secondary water circulation system, resulting in a more compact structure and higher integration, making it particularly suitable for applications with strict limitations on size and weight or where extremely high heat dissipation power is not required.

[0035] In this embodiment, the internal heat absorption unit 1 is not an external, independent component, but rather a microscale flow channel network directly embedded within the substrate of the slow-wave structure 7 using precision machining techniques, or closely surrounding and arranging itself around known hotspot areas within the slow-wave structure 7—specifically, areas where the electromagnetic field of the electron beam channel 6 interacts strongly with the folded waveguide, resulting in the most severe electron beam interception and thus the highest heat flux density. For example, this flow channel network can be machined within the metal block of the slow-wave structure 7, adjacent to the waveguide wall or the wall of the electron beam channel 6. This "embedded" design minimizes the heat transfer path, virtually eliminating contact thermal resistance and ensuring that heat is carried away by the working fluid with the shortest path and highest efficiency, which is the structural basis for achieving efficient cooling.

[0036] To further optimize system integration and reliability, the interface design of the sealed circulation pipeline 3 connecting the internal and external systems is crucial. A preferred implementation is to integrate this pipeline with the electromagnetic wave input terminal 8 and output terminal 9 inherent on the slow-wave structure 7. For example, utilizing the structural space of the existing RF connection port or flange on the slow-wave structure 7, the micro-pipelines for the working fluid inflow and outflow can be integrated into the port assembly, enabling both electromagnetic signal transmission and fluid-sealed connection. This design avoids the need for additional openings or welding of new connectors on the extremely compact slow-wave structure 7, maximizing structural integrity and mechanical strength, and simplifying the overall assembly process.

[0037] Regarding the working medium of the system, deionized water is an excellent choice. It has advantages such as high latent heat of vaporization, chemical stability, non-toxicity, and low cost. During implementation, its purity must be ensured to prevent electrochemical corrosion or scaling. Of course, other phase change working media, such as fluorinated liquids, can also be selected depending on the specific operating temperature and pressure range requirements.

[0038] To further enhance the heat transfer performance of the internal heat-absorbing unit 1 and facilitate the reflux of the liquid working fluid, specific microstructures 10 can be designed and fabricated on the inner wall of its microscale flow channels. These microstructures 10, such as rough surfaces, micropillar arrays, grooves, sintered copper powder layers, and sintered copper mesh layers, can significantly increase the heat transfer area, promote nucleated boiling, and thus improve the efficiency of phase change heat transfer. More importantly, when these microstructures 10 are designed as regular arrays with specific dimensions and spacing, such as parallel fin arrays extending along the flow channel direction, they can generate strong capillary forces. This capillary force is one of the core driving forces that propel the condensate from the external cooling unit 2 to overcome flow resistance, especially the reverse gravity, and reliably reflux back to the internal heat-absorbing unit 1. The dimensions of the fins, such as height, width, and spacing, can be optimized according to the working fluid characteristics, heat load, and processing capabilities, which can be determined by those skilled in the art through conventional experiments.

[0039] Microscale structures, such as sintered copper powder, grooves, and sintered copper mesh, can also be formed on the inner surfaces of external heat exchange units and connecting pipes to enhance condensation and liquid reflux.

[0040] To ensure stable startup and operation of the circulation system, the entire closed loop must undergo rigorous vacuuming before final injection of the working fluid. This step aims to remove non-condensable gases from the loop, which accumulate in the condensation section, forming gas locks that severely degrade heat transfer and hinder the circulation of the working fluid. After vacuuming, the loop can maintain a negative pressure state, or, depending on the saturated vapor pressure characteristics of the selected working fluid, an appropriate amount of working fluid can be injected to create a specific gas-liquid two-phase equilibrium environment. This pretreatment process is essential for the reliable and efficient operation of this system.

[0041] Example 2 This embodiment provides a traveling wave tube (TWT). By integrating the phase-change circulating heat dissipation device described in Embodiment 1 with other TWT components, including an electron gun, a slow-wave structure 7, a collector electrode, and a magnetic focusing system, a novel TWT with efficient heat dissipation, stable operation, and longer lifespan can be constructed. The slow-wave structure 7 itself can adopt forms known in the art, such as folded waveguides. Its specific geometric parameters, such as period, slot width, and ridge width, are designed according to the operating frequency band. This is mature existing technology and will not be elaborated further here.

[0042] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention, and do not imply or require that the device or element referred to must have a specific orientation or construction method, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish the objects of description and should not be construed as limiting importance or order, and the features defined by such terms may explicitly or implicitly include one or more of those features. Unless otherwise stated, "a plurality of" in the description of this invention refers to two or more.

[0043] The terms "installation," "connection," and "joining" should be interpreted broadly, unless otherwise explicitly defined, to include, but are not limited to, fixed connections, detachable connections, or integrally formed connections; mechanical or electrical connections; direct connections or indirect connections via an intermediate medium; and internal communication between two components. Those skilled in the art can understand their meaning based on the specific technical solution. The fixed connections involved in this invention, unless otherwise stated, include both detachable fixed connections (such as bolt and screw connections) and non-detachable fixed connections (such as riveting and welding), and may also include integral structures achieved through an integral forming process (such as casting) (except where integral forming is clearly not feasible).

[0044] Unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes cover states or shapes that are similar to, close to, or adjacent to them.

[0045] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured using a one-piece molding process.

[0046] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0047] In the embodiments of this application, the same reference numerals are used to denote the same component or part.

[0048] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0049] It should be noted that, for those skilled in the art, it is obvious 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 the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, 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 phase transition circulating heat sink for a traveling wave tube slow wave structure, characterized by, It comprises: An internal heat absorption unit (1), an external cooling unit (2), and a sealed circulation pipeline (3) connecting the two, which form a closed loop of working medium circulation; The internal heat absorption unit (1) is a micro-scale flow channel network integrated in the body substrate of the slow wave structure (7), which is used to directly contact and absorb the heat generated by the slow wave structure (7) during operation; The external cooling unit (2) is arranged outside the traveling wave tube, which is used to dissipate the heat carried by the working medium to the external environment; The closed loop is filled with working medium, which undergoes phase change from liquid to gas after absorbing heat at the internal heat absorption unit (1), forming a steam flow, and flows to the external cooling unit (2) through the sealed circulation pipeline (3) under the action of pressure difference; The steam flow condenses into liquid after releasing heat at the external cooling unit (2), and the condensed liquid working medium flows back to the internal heat absorption unit (1) under the driving of gravity, capillary force or pressure difference, completing the circulation.

2. The phase-transition recycling heat sink for a traveling wave tube slow wave structure of claim 1, wherein: The external cooling unit (2) is a liquid cooling plate heat exchanger (4), which is provided with a secondary cooling fluid flow channel inside, which is used to exchange heat between the secondary cooling fluid and the working medium steam or condensed liquid from the internal heat absorption unit (1), and finally lead out the heat.

3. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The external cooling unit (2) is a finned air-cooled condenser (5), which condenses the working medium steam flowing through it and releases heat through forced air cooling or natural convection.

4. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The micro-scale flow channel network of the internal heat absorption unit (1) is directly embedded or arranged around the high heat flux density area of the electron beam passage (6) and the slow wave structure (7) in the slow wave structure (7).

5. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The sealed circulation pipeline (3) is designed to be integrated with the structure of the electromagnetic wave input end (8) and the output end (9) of the slow wave structure (7) to avoid introducing additional connecting components and ensure the compactness of the structure.

6. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The working medium is deionized water.

7. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The inner wall of the micro-scale flow channel of the internal heat absorption unit (1) is processed with microstructure (10), which is used to enhance the heat exchange efficiency of the working medium and provide capillary force to drive the return of liquid working medium.

8. The phase-transition cyclic heat spreading device for a traveling wave tube slow wave structure of claim 7, wherein: The microstructure (10) is a parallel fin array extending in the flow direction.

9. The phase change thermal cycle heat spreading device for a traveling wave tube slow wave structure of claim 1, wherein: The closed loop is subjected to vacuumizing treatment before packaging, so that the inside of the loop maintains a negative pressure or a specific working medium saturated steam pressure environment after the working medium is injected.

10. A traveling wave tube, characterized by: It comprises the phase change circulation heat dissipation device according to any one of claims 1-9. It comprises the phase change circulation heat dissipation device according to any one of claims 1-9.

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