A top surface wave antenna of a spherical tokamak

Abstract

The present invention discloses a top surface wave antenna for a spherical tokamak, comprising a feed waveguide, a brim, a sub-waveguide, and a metal base. The feed waveguide's lower end is connected to one end of the metal base, and one side is connected to the brim, with the brim oriented along the length of the metal base. Several sub-waveguides are evenly spaced on the metal base, with their tops no higher than the height of the metal base. The sub-waveguides are arranged in an ascending zigzag pattern, and the feed waveguide serves as a microwave input port. This invention is primarily applicable to high-power tokamak systems, where it can be driven with low clutter currents in conjunction with an external antenna, achieving enhanced performance. The sub-waveguides are arranged in a zigzag pattern, exhibit a compact structure, and offer stable performance and excellent test results, meeting experimental and processing requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of surface wave antennas, and in particular to a top surface wave antenna of a spherical tokamak. Background Art

[0002] Low-stray current drive is recognized as one of the most effective non-inductive current drive methods for tokamaks. In spherical tokamaks, the antennas used for low-stray current drive are divided into outer antennas and top antennas. Experiments with non-inductive plasma current startup have been conducted on tokamaks using low-power external antennas, achieving promising results. However, the density limit has led researchers to recognize the limitations of external antennas, necessitating the design of a top antenna to facilitate power absorption in the plasma core. Summary of the Invention

[0003] The purpose of the present invention is to provide a top surface wave antenna for a spherical tokamak to solve the problem of density limit involved in the current drive of the low-noise external antenna of a small tokamak in the above-mentioned prior art, so that the surface wave antenna and the peripheral antenna complement each other, have stable performance, good test results, and meet experimental requirements.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a top surface wave antenna for a spherical tokamak, comprising a feeding waveguide, a brim, a sub-waveguide, and a metal base. The lower end of the feeding waveguide is connected to one end of the metal base, and one side is connected to the brim, with the brim facing the length direction of the metal base. A plurality of sub-waveguides are arranged at equal intervals on the metal base, the tops of the sub-waveguides do not exceed the height of the metal base, and the sub-waveguides are arranged in an ascending broken line trend. The feeding waveguide is used as a microwave input port.

[0006] Preferably, the through opening of the feeding waveguide is rectangular, the bottom surface of the feeding waveguide is flush with the top of the metal base, and the starting height of the sub-waveguide is not higher than the bottom surface of the feeding waveguide.

[0007] Preferably, the brim is in an inverted U-shape, the top surface of the brim is flush with the top surface of the feeding waveguide, both side surfaces are right triangles, and both side surfaces are connected to the side walls of the feeding waveguide.

[0008] Preferably, two platforms and two steps are provided on the metal base, and the first platform, the first step, the second platform, and the second step are connected in sequence. The sub-waveguides provided on the first platform, the first step, and the second platform have the same height, the top of the sub-waveguide on the second step is flush with the top of the sub-waveguide on the second platform, the height of each step on the first step and the second step is 0 mm-100 mm, and the depth of the radiation gaps provided on the first platform, the first step, and the second platform is 0 mm-100 mm.

[0009] Preferably, the height of each step of the first step is 3.38 mm, and the height of each step of the second step is 5 mm.

[0010] Preferably, the width of the radiation gap between adjacent sub-waveguides is 0 mm-100 mm, and the depth of the radiation gap provided on the first platform, the first step and the second platform is 27 mm-28 mm.

[0011] Preferably, the number of the sub-waveguides is 0-100, the thickness of the sub-waveguides is 0mm-100mm, and the height is 0mm-100mm.

[0012] Preferably, the number of the sub-waveguides is 27, and the thickness and spacing of the sub-waveguides are both 5 mm.

[0013] Preferably, the total length of the feeding waveguide and the metal base is no more than 240 mm, and the parallel refractive index n11 of the top surface wave antenna is 0-10.

[0014] Preferably, the feeding waveguide, the brim, the sub-waveguide and the metal base are made of copper, aluminum, iron or stainless steel.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The present invention is mainly used in high-power tokamak systems, and can work together with an external antenna to drive low-clutter current to achieve better results. The sub-waveguides are arranged in a zigzag pattern and have a compact structure, stable performance, good test results, and meet experimental and processing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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. 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.

[0018] Figure 1 Schematic diagram of the structure of the top surface wave antenna of the spherical tokamak of the present invention Figure 1 ;

[0019] Figure 2 Schematic diagram of the structure of the top surface wave antenna of the spherical tokamak of the present invention Figure 2 ;

[0020] Figure 3 Schematic diagram of the structure of the top surface wave antenna of the spherical tokamak of the present invention Figure 3 ;

[0021] Figure 4 This is a graph showing actual test results of the reflection coefficient of the top surface wave antenna of the spherical tokamak of the present invention;

[0022] Figure 5 is a parallel refractive index diagram of the top surface wave antenna of the spherical tokamak of the present invention;

[0023] Among them: 1-feed waveguide, 2-brimstone, 3-metal base, 4-sub-waveguide, 5-radiation slot, 6-first platform, 7-first step, 8-second platform, 9-second step. DETAILED DESCRIPTION

[0024] 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide a top surface wave antenna for a spherical tokamak to solve the problem of density limit involved in the current drive of the low-clutter external antenna of a small tokamak in the prior art, so that the surface wave antenna and the peripheral antenna complement each other, have stable performance, good test results, and meet experimental requirements.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figures 1 to 5 As shown: This embodiment provides a top surface wave antenna of a spherical tokamak, including a feeding waveguide 1, a brim 2, a sub-waveguide 4 and a metal base 3. The lower end of the feeding waveguide 1 is connected to one end of the metal base 3 and one side is connected to the brim 2. The brim 2 faces the length direction of the metal base 3. Several sub-waveguides 4 are arranged at equal intervals on the metal base 3. The top of the sub-waveguide 4 does not exceed the height of the metal base 3. The sub-waveguides 4 are arranged in an ascending broken line trend. The feeding waveguide 1 is used as a microwave input port.

[0028] The feed waveguide 1 has a rectangular opening and a single left-side input port. For experiments, the focus is solely on the reflection coefficient. The bottom of the feed waveguide 1 is flush with the top of the metal base 3, and the sub-waveguide 4 begins at a height no higher than the bottom of the feed waveguide 1. The brim 2 is an inverted U-shape, with its top flush with the top of the feed waveguide 1 and its two side faces forming right triangles, both connected to the sidewalls of the feed waveguide 1. This configuration promotes uniform microwave conduction.

[0029] The metal base 3 is equipped with two platforms and two steps. The first platform 6, first step 7, second platform 8, and second step 9 are connected in sequence. The sub-waveguides 4 arranged on the first platform 6, first step 7, and second platform 8 are of the same height. The top of the sub-waveguide 4 on the second step 9 is flush with the top of the sub-waveguide 4 on the second platform 8. The height of each step of the first step 7 is 3.38 mm, and the height of each step of the second step 9 is 5 mm. The height of each step is unequal to the height of the sub-waveguide 4. The thickness of the sub-waveguide 4 is consistent, which improves and enhances the antenna's radiation performance and improves the propagation of microwaves.

[0030] The width of the radiating slots 5 between adjacent sub-waveguides 4 is 0-100 mm. The number of sub-waveguides 4 is 0-100, and the thickness and height of the sub-waveguides 4 are 0-100 mm and 0-100 mm, respectively. The thickness, number, and spacing of the sub-waveguides 4 can be appropriately adjusted based on transmission line principles, antenna performance, and reflection coefficient settings. In this embodiment, there are 27 sub-waveguides 4 and 28 radiating slots 5. The depth of the radiating slots 5 provided on the first platform 6, first step 7, and second platform 8 is 0-100 mm, preferably 27-28 mm. The thickness and spacing of the sub-waveguides 4 (radiating slots 5) are both 0-100 mm, preferably 5 mm.

[0031] The total length of the feed waveguide 1 and metal base 3 is no greater than 240 mm, and the parallel refractive index n11 of the top surface wave antenna is 0-10. The antenna of this embodiment has a dimension of 210 mm along the microwave transmission direction. Because the top antenna needs to extend into a 240 mm diameter metal cylinder to reach the plasma region, the antenna length must not exceed 240 mm, and the width can be adjusted based on actual needs. The materials of the feed waveguide 1, brim 2, sub-waveguide 4, and metal base 3 are not limited to copper, aluminum, iron, or stainless steel. The sub-waveguide 4 and metal base 3 can be manufactured as a single piece.

[0032] The top surface wave antenna of the spherical tokamak of this embodiment complements and works together with the peripheral antenna. Microwaves are input into one port and output from the other port. The antenna radiates energy through serrations and slots to generate plasma. It is mainly used in high-average-power microwave systems, especially in the low-noise drive of the tokamak. The thickness of the sub-waveguide 4, the depth of the radiation slot 5, and the step height complement each other and jointly determine the performance, reflection coefficient, field strength distribution, parallel refractive index, etc. of the antenna. After the antenna is processed and formed, it can be debugged to meet engineering requirements, and the experimental test results are good.

[0033] like Figure 4 The figure shows the actual test results of the reflection coefficient of the antenna of this embodiment. The test results vary slightly with the processing materials (gold, silver, copper, aluminum, stainless steel, etc.). The central operating frequency is 2.45GHz, at which point S11 (reflection coefficient) = -17dB, about 99% of the microwave energy is radiated into the air, and the energy reflected back from the port of feed waveguide 1 is less than 1%. The microwave bandwidth is 6MHz. Figure 5 The figure shows the parallel refractive index diagram of the antenna of this embodiment, wherein the central operating frequency is 2.45 GHz, at which point n11 (parallel refractive index) = 3.6, and the parallel refractive index n11 associated with the antenna = 0-100. The figure shows that the top surface wave antenna has good directivity.

[0034] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A top surface wave antenna of a spherical tokamak, characterized by: The invention comprises a feeding waveguide, a brim, a sub-waveguide and a metal base, wherein the lower end of the feeding waveguide is connected to one end of the metal base and one side is connected to the brim, the brim faces the length direction of the metal base, a plurality of sub-waveguides are arranged at equal intervals on the metal base, the top of the sub-waveguide does not exceed the height of the metal base, the sub-waveguides are arranged in an ascending broken line trend, and the feeding waveguide is used as a microwave input port; the through opening of the feeding waveguide is rectangular, the bottom surface of the feeding waveguide is flush with the top of the metal base, and the starting height of the sub-waveguide is not higher than the bottom surface of the feeding waveguide; the brim is in an inverted U shape, the top surface of the brim is flush with the top surface of the feeding waveguide, the two side surfaces are right triangles, and both side surfaces are connected to the side walls of the feeding waveguide.

2. The top surface wave antenna of the spherical tokamak according to claim 1, characterized in that: Two platforms and two steps are provided on the metal base. The first platform, the first step, the second platform, and the second step are connected in sequence. The sub-waveguides provided on the first platform, the first step, and the second platform have the same height. The top of the sub-waveguide on the second step is flush with the top of the sub-waveguide on the second platform. The height of each step on the first step and the second step is 0 mm-100 mm. The depth of the radiation gaps provided on the first platform, the first step, and the second platform is 0 mm-100 mm.

3. The top surface wave antenna of the spherical tokamak according to claim 2, characterized in that: The height of each step of the first step is 3.38 mm, and the height of each step of the second step is 5 mm.

4. The top surface wave antenna of the spherical tokamak according to claim 2, characterized in that: The width of the radiation gap between adjacent sub-waveguides is 0 mm-100 mm, and the depth of the radiation gaps provided on the first platform, the first step and the second platform is 27 mm-28 mm.

5. The top surface wave antenna of the spherical tokamak according to claim 1, characterized in that: The number of the sub-waveguides is 0-100, the thickness of the sub-waveguides is 0mm-100mm, and the height is 0mm-100mm.

6. The top surface wave antenna of the spherical tokamak according to claim 5, characterized in that: The number of the sub-waveguides is 27, and the thickness and spacing of the sub-waveguides are both 5 mm.

7. The top surface wave antenna of the spherical tokamak according to claim 1, characterized in that: The total length of the feeding waveguide and the metal base is not greater than 240 mm, and the parallel refractive index of the top surface wave antenna is n 11 =0-100.

8. The top surface wave antenna of the spherical tokamak according to claim 1, characterized in that: The feeding waveguide, the brim, the sub-waveguide and the metal base are made of copper, aluminum, iron or stainless steel.

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