A frequency-tunable terahertz gyrotron collector

Abstract

The present invention discloses a frequency-tunable terahertz gyrotron collector, which belongs to the technical field of terahertz electric vacuum devices and relates to electron cyclotron maser devices. This structure is used for a frequency-tunable terahertz gyrotron developed in a laboratory, and is a component that collects residual electrons and dissipates electron energy in a water-cooling manner. The collector is connected to the rear end of the gyrotron interaction cavity, and includes a cylindrical hollow cavity and outer wall heat sinks. Each heat sink is a straight rib structure and is located on the outer wall of the collector cylindrical cavity. The gaps between adjacent heat sinks serve as cooling water channels. The straight rib heat dissipation structure is combined with a water-cooling inlet. Through the design of a special collection stage structure, the heat exchange area between the collector and the coolant is increased, the water cooling efficiency is improved, and the collection stage temperature is reduced, thereby improving the stability of the gyrotron operation and ensuring the service life of the gyrotron.

Description

Technical Field

[0001] The present invention relates to the field of terahertz technology, in particular to an electric vacuum gyrotron device, which is a novel collector structure for a frequency-tunable terahertz gyrotron. Background Art

[0002] Terahertz waves occupy a unique position in the electromagnetic spectrum. Their long-wavelength range overlaps with millimeter waves, while their short-wavelength range overlaps with infrared radiation, placing them between microwaves and infrared. Terahertz waves have a wide range of applications in astrophysics, materials science, biomedicine, environmental science, spectroscopy and imaging, and information science. Terahertz gyrotrons are high-power terahertz sources with significant development potential. Operating by stimulated emission of electron cyclotron radiation, they fill the gap in the spectrum between microwave and infrared bands. In the frequency range of 100 GHz and above, gyrotrons can generate power far exceeding that of solid-state devices and other traditional slow-wave devices, demonstrating their enormous potential and becoming a recognized source of coherent radiation for long-pulse and continuous-wave systems in the millimeter-wave and terahertz bands. They have broad applications in ion cyclotron heating, electron cyclotron resonance heating, nuclear magnetic resonance, and dynamic nuclear polarization, and are receiving considerable international attention. When operating in the millimeter-wave or terahertz bands, gyrotrons face challenges such as small dimensions and excessively high collector temperatures. The collector is a crucial component in a gyrotron that recovers excess electrons and dissipates excess energy. Electrons exchange energy through high-frequency structures, and a large amount of excess electrons after interaction enter the collector. During operation, the collector's inner wall is bombarded by high-energy electrons, generating significant heat and causing the collector temperature to rise. The collector is the component most susceptible to heat generation in the gyrotron. As a vacuum device, excessive temperatures can cause outgassing from the collector material, leading to a decrease in the device's internal vacuum. Excessive temperatures can even cause thermal deformation or device meltdown. Therefore, collector temperature not only affects the efficiency and stability of the entire device but also its service life. Therefore, conducting research on collector thermal design is crucial to ensuring the reliability, stability, and longevity of the gyrotron. This resulting increase in collector temperature can cause desorption of adsorbed gases on the material's surface and even spontaneous evaporation and vaporization of the material itself, severely impacting the efficiency and stability of the gyrotron. Therefore, we need to design a new collector stage structure to achieve high power density per unit area. In their 2015 paper, "Design of Curved Collector for Q-Band Gyro-TWT," presented at the IEEE Vacuum Electronics Conference, Jiang Wei, Yan Ran, and others from the University of Electronic Science and Technology of China proposed a curved collector stage for collecting power at a density of 0.38 kW / cm². This stage is designed for Q-band gyro-TWTs and operates at a temperature of 142°C, achieving good results. However, this structure can experience sparking at higher power densities due to excessive temperature. Summary of the Invention

[0003] In response to the above problems, the present invention proposes a water-cooled heat dissipation collector structure for a gyrotron. This structure is based on a frequency-tunable terahertz gyrotron developed in the laboratory, and aims to solve technical problems such as the rapid temperature rise and high temperature of the existing collector, and the need to coordinate with the inlet and outlet of the water cooler.

[0004] This invention is achieved through the following technical solutions: analyzing factors influencing the temperature of the collection stage and, through material selection and specialized structural design, reducing the maximum temperature of the collection stage and liquid cooling, thereby lowering the temperature rise of the gyrotron collector during operation and increasing the power density per unit area. The material used is oxygen-free copper with high thermal conductivity, and the outer wall of the structure is optimized with straight fins. This effectively increases the contact area for convective heat transfer, increases the degree of turbulence, improves the heat dissipation efficiency of the collector, reduces the temperature of the collection stage and liquid cooling, and ensures the stability of the gyrotron operation.

[0005] Therefore, the technical solution of the present invention is: a water-cooled gyrotron collector, the collector structure comprising a hollow cylindrical body, the inner side of which is connected to the front structure and has a smooth wall surface. In addition, the outer side of the collector body structure is designed with fin-type heat sinks to increase the heat dissipation area.

[0006] A further improvement is that the collecting electrode hollow cylindrical main structure has an inner diameter of 10 mm, an outer diameter of 22 mm, a wall thickness of 6 mm and a length of 700 mm.

[0007] A further improvement is that the fin-type heat sink on the outer side of the collector main structure is a rectangular straight rib structure.

[0008] A further improvement is that the collector includes 24 heat sinks, which are divided into 3 groups, each with 8 fins. Taking into account various factors such as water inlet flow rate, pressure, and structural processing, this structure has the best heat dissipation effect.

[0009] A further improvement is that the height of the collector heat sink is 10 mm and the thickness of the heat sink is 1.5 mm.

[0010] The advantages of the present invention are: through the design of a special structure collector, the water cooling heat dissipation efficiency is greatly improved, the collector and internal water temperatures are reduced, thereby reducing the collector temperature, reducing the thermal deformation of the device, ensuring the stability and service life of the device, and at the same time being easy to process and control processing costs.

[0011] The beneficial effects of the present invention are as follows: through the design of a special structure collection stage, the water cooling heat dissipation efficiency of the gyrotron is greatly improved, the collector and liquid cooling temperatures are reduced, and thus the design is simple and low-cost to solve the problem of excessively high collector temperature in the existing gyrotron affecting the stability and service life of the gyrotron. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 It is a structural schematic diagram of the present invention;

[0014] Figure 2 is the gyrotron electron motion trajectory in an embodiment of the present invention;

[0015] Figure 3 is a diagram of collector power density distribution in an embodiment of the present invention;

[0016] Figure 4 is a temperature distribution diagram of the inner wall in the embodiment of the present invention;

[0017] Figure 5 3 is a temperature distribution diagram of the cross section at the maximum temperature in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] Example

[0020] See also Figure 1 A frequency-tunable terahertz spiral collector comprises a hollow cylindrical cavity and multiple cooling fins mounted on its outer wall. Each fin is a straight rib structure surrounding the cavity, with gaps between adjacent fins serving as cooling water channels. The collector's hollow cylindrical cavity has an inner radius of 5mm, an outer radius of 11mm, a wall thickness of 6mm, and a length of 700mm. It includes 24 cooling fins, each 1.5mm thick and 10mm high.

[0021] Example

[0022] See also Figure 1 Gyrotrons are vacuum devices that require heating and packaging in hydrogen. The presence of oxygen can lead to hydrogen disease, causing device damage in a high vacuum environment. Vacuum devices require strict control of the oxygen content in the material. Therefore, the copper used in gyrotrons must be high-purity oxygen-free copper. TU1 oxygen-free copper is used as the collector material.

[0023] Example

[0024] See also Figure 2 When a gyrotron is operating, a magnetron-controlled injection electron gun generates a hollow electron beam. The electrons perform cyclotron motion in a strong magnetic field of several Teslas. Under adiabatic compression, the electrons' longitudinal velocity is continuously converted into transverse velocity. In the resonant cavity, the electrons interact with the electromagnetic field, generating high-frequency power. This high-frequency power is output through a waveguide and output window. The resulting electrons, carrying a large amount of energy, strike the collector, causing the collector temperature to rise. Correctly using simulation software to simulate the electron's trajectory and impact point lays the foundation for collector temperature analysis.

[0025] Example

[0026] See also Figure 3 The electron landing position and the distribution of the number of electrons correspond to the distribution of the power density on the inner wall of the collector. The axial coordinates of the electron landing point are processed and the axial distribution of the collector power density is obtained by calculation. Figure 3 As shown. The peak power density reaches 1594W / cm 2 , exceeding the threshold that the collector can withstand for stable continuous wave operation, the design of the heat sink can avoid thermal deformation of the collector due to high temperature.

[0027] Example

[0028] See also Figure 4 The axial distribution of the heat flux density on the inner wall of the gyrotron collector is Figure 3 As shown, the peak power density is 1594W / cm 2 When the collector water cooling inlet flow rate is 10m / s and the water temperature is 10℃, the axial temperature distribution of the collector is consistent with the electron landing area.

[0029] Example

[0030] See also Figure 5 The temperature distribution of the collector cross section shows that the maximum temperature is 293°C on the inner wall and 185°C on the outer wall. The designed heat sink structure can effectively dissipate heat, ensuring the reliability and stability of the gyrotron operation, and ensuring that the gyrotron collector can work stably under continuous wave conditions while ensuring the service life of the gyrotron.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water-cooled heat dissipation structure collector for a frequency-tunable terahertz gyrotron, characterized by: The structure is based on a 263GHz frequency-tunable terahertz gyrotron developed in the laboratory, and consists of a collector cavity and a heat sink structure on the outer wall of the collector. The collector is connected to the end of the interaction cavity to collect the remaining electrons after the interaction. The collector structure is a hollow cylindrical cavity with a smooth inner wall and no inclination. The heat sink is designed on the outer wall of the collector cavity to increase the convection heat exchange area between the collector structure and the cooling water, thereby reducing the collection temperature. The heat sink adopts a rectangular fin structure, and the heat sink is perpendicular to the tangent of the outer circle of the collector cross section and is radially distributed on the outer wall of the collector. To avoid the water inlet pipe, the heat sink is divided into three groups, with 8 pieces in each group, for a total of 24 pieces.

2. The water-cooling heat dissipation structure for a frequency-tunable terahertz gyrotron collector according to claim 1, characterized in that: The collector cavity structure and the outer wall heat sink structure are rotationally symmetric about the z-axis; the collector cavity length is 700 mm, the inner radius is 5 mm, the outer radius is 11 mm, and the wall thickness is 6 mm; the external heat sink is a rectangular fin type with a length consistent with the collector structure, a heat sink thickness of 1.5 mm, and a height of 10 mm.

3. The water-cooling heat dissipation structure for a frequency-tunable terahertz gyrotron collector according to claim 1, characterized in that: The material used for processing the collector cavity and the outer wall heat sink structure is TU1 oxygen-free copper.

4. The water-cooling heat dissipation structure for a frequency-tunable terahertz gyrotron collector according to claim 1, characterized in that: The equivalent peak heat flux density on the inner wall of the collector is 1594W / cm 2 .

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