A tokamak outer antenna

Abstract

This invention discloses a tokamak outer antenna, comprising a feed waveguide, a cap, sub-waveguides, and a metal base. The metal base is W-shaped, with both ends connected to the lower surface of a feed waveguide. The opposite sides of the two feed waveguides are connected to a cap. Several sub-waveguides are evenly spaced on the upper surface of the metal base, each sub-waveguide's height not exceeding that of the feed waveguide. One feed waveguide serves as a microwave input port, and the other as a microwave output port. This tokamak outer antenna is a novel antenna with simple feeding, low reflection and transmission coefficients, and high directivity. It features a compact antenna arrangement, high stability, and good performance, and is primarily applied in high-average-power microwave systems, especially low-clutter driven tokamak systems.

Description

Technical Field

[0001] This invention relates to the technical field of external antennas, and in particular to an external antenna for a tokamak. Background Technology

[0002] Low-hybrid current drive is one of the most effective non-inductive current drive methods for tokamak nuclear fusion, experimentally proven internationally. The antenna, as a crucial core component of the system, plays a vital role in feeding power into the plasma. Currently, traditional large-scale tokamak devices internationally generally employ multi-junction waveguide array antennas with parallel refractive indices... n 11 Generally, the value is less than 3, such as EAST, HL-1, JET, etc. Since 1990, countries such as Japan have developed a spherical tokamak, which is relatively small in size and uses radio frequency ion cyclotron (ICRF) as the main driving method, achieving certain results and proving the feasibility of small tokamak.

[0003] The spherical tokamak focuses on compactness, pollution-free operation, and low cost, aiming to commercialize fusion energy within thirty years. Currently, traditional multi-junction waveguide array antennas cannot meet the requirements of spherical tokamaks because their parallel refractive index is low, making it impossible to penetrate the dense plasma layer to reach the plasma core region. Therefore, antenna technology in this field is essentially nonexistent and represents a significant technical challenge that urgently needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide an external antenna for a tokamak to solve the problem of low clutter current driving in small tokamaks in the prior art, thereby making the metal antenna simple to feed, with low reflection and transmission coefficients and high directivity.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a tokamak outer antenna, comprising a feed waveguide, a cap, sub-waveguides, and a metal base. The metal base is W-shaped, with both ends connected to the lower surface of one of the feed waveguides. The opposite sides of the two feed waveguides are connected to a cap. A plurality of sub-waveguides are evenly spaced on the upper surface of the metal base, and the height of each sub-waveguide does not exceed the height of the feed waveguide. One feed waveguide is used as a microwave input port, and the other feed waveguide is used as a microwave output port.

[0007] Preferably, the through-hole of the feed waveguide is rectangular, the bottom surface of the feed waveguide is flush with the top surface of the metal base, and the starting height of the sub-waveguide is not higher than the bottom surface of the feed waveguide.

[0008] Preferably, the brim is in the shape of an inverted U and symmetrically connected to the feed waveguides at both ends. The top surface of the brim is flush with the top surface of the feed waveguide, and both sides are right-angled triangles, with both sides connected to the sidewalls of the feed waveguide.

[0009] Preferably, the base plate of the metal base is arched, and two stepped surfaces are symmetrically arranged on the base plate. Both ends of each stepped surface are flat. The vertical lengths of the sub-waveguides arranged on the base plate are the same and are all 0mm-100mm.

[0010] Preferably, the height of each step on the stepped surface is 0mm-100mm; the length of the feeding waveguide is at least 100mm and the width is at least 20mm; the length of the brim along the microwave conduction direction is at least 20mm.

[0011] Preferably, the radiating gap between adjacent sub-waveguides is filled with air or vacuum, the number of radiating gaps is at least 16, the width of the radiating gap is 0mm-100mm, and the depth of the radiating gap is 0mm-100mm.

[0012] Preferably, the number of radiation slits is 28 and the depth is 28 mm.

[0013] Preferably, the number of sub-waveguides is 0-100, and the thickness of the sub-waveguides is 0mm-100mm.

[0014] Preferably, the number of sub-waveguides is 27, the thickness of the sub-waveguides is 1.5 mm, and the spacing between them is 5 mm.

[0015] Preferably, the feed waveguide, the cap brim, the sub-waveguide, and the metal base are made of copper, aluminum, iron, or stainless steel.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] The tokamak outer antenna of the present invention is a novel antenna with simple feeding, low reflection and transmission coefficient, and high directivity. The antenna is compactly arranged, highly stable, and performs well. It is mainly used in high average power microwave systems, especially low clutter driven tokamak systems. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram of the structure of the outer antenna of the tokamak according to the present invention. Figure 1 ;

[0020] Figure 2 This is a schematic diagram of the structure of the outer antenna of the tokamak according to the present invention. Figure 2 ;

[0021] Figure 3 This is a schematic diagram of the structure of the outer antenna of the tokamak according to the present invention. Figure 3 ;

[0022] Figure 4 This is a diagram showing the S-parameters of the outer antenna of the tokamak according to the present invention;

[0023] Figure 5 This is a parallel refractive index diagram of the outer antenna of the tokamak of the present invention;

[0024] Wherein: 1-feed waveguide, 2-cap brim, 3-metal base, 4-sub-waveguide, 5-radiating slot. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0026] The purpose of this invention is to provide an external antenna for a tokamak to solve the problem of low clutter current driving in small tokamaks in the prior art, making the metal antenna simple to feed, with low reflection and transmission coefficient and high directivity.

[0027] 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.

[0028] like Figures 1 to 5 As shown: This embodiment provides a tokamak outer antenna, including a feed waveguide 1, a cap 2, sub-waveguides 4, and a metal base 3. The metal base 3 is W-shaped, with both ends of the metal base 3 connected to the lower surface of a feed waveguide 1, and the opposite sides of the two feed waveguides 1 connected to a cap 2. Several sub-waveguides 4 are evenly spaced on the upper surface of the metal base 3, and the height of each sub-waveguide 4 does not exceed the height of the feed waveguide 1. One feed waveguide 1 is used as a microwave input port, and the other feed waveguide 1 is used as a microwave output port.

[0029] The feed waveguide 1 has a rectangular opening, and its bottom surface is flush with the top of the metal base 3. The initial height of the sub-waveguide 4 is no higher than the bottom surface of the feed waveguide 1. The brim 2 is inverted U-shaped and symmetrically connected to the feed waveguides 1 at both ends. The top surface of the brim 2 is flush with the top surface of the feed waveguide 1, and both sides are right-angled triangles connected to the sidewalls of the feed waveguide 1. To ensure that the microwave coupled into the antenna at the left port meets the requirements for field strength distribution, the brim 2 on both sides is completely symmetrical.

[0030] The metal base 3 has an arched base plate with two symmetrical stepped surfaces. Each stepped surface has two flat ends. The metal base 3 and the sub-waveguide 4 are integrally formed. The sub-waveguides 4 on the base plate have the same vertical length, ranging from 0mm to 100mm. The sloped metal plate allows the antenna tip to be as close to the plasma as possible, and adjusts the parallel refractive index and S-parameters to adapt to plasma conditions at different distances. Each step of the stepped surface has a height of 0mm-100mm; the feed waveguide 1 has a length of at least 100mm and a width of at least 20mm; the visor 2 has a length of at least 20mm along the microwave propagation direction. In this embodiment, the height of each step is 2.25mm, the length of the visor 2 is 28mm, and the width of the feed waveguide 1 is 20mm and the length is 111.5mm. These dimensions can be adjusted and designed appropriately within permissible limits to provide sufficient power to the antenna.

[0031] The radiating gaps 5 between adjacent sub-waveguides 4 are filled with air or a vacuum. There are at least 16 radiating gaps 5, with a width and depth of 0mm-100mm. Alternatively, there may be 28 radiating gaps 5 with a depth of 28mm. The number of sub-waveguides 4 can range from 0 to 100, with a thickness of 0mm-100mm. In this embodiment, there are 27 sub-waveguides 4, with a thickness of 1.5mm and a spacing of 5mm. The number and size of the sub-waveguides 4 and radiating gaps 5 can be determined according to actual requirements. In this embodiment, 27 sub-waveguides 4 and 28 radiating gaps 5 are arranged sequentially on the metal base 3. The width of the sub-waveguides 4 and radiating gaps 5 is consistent with the wide side dimension of the feed waveguide 1; the maximum height of the sub-waveguide 4 is flush with the height of the brim 2.

[0032] The materials of the feed waveguide 1, cap 2, sub-waveguide 4 and metal base 3 are not limited to copper, aluminum, iron or stainless steel.

[0033] The tokamak outer antenna of this embodiment is a highly directional metal antenna with simple feeding, low reflection and transmission coefficients, and a parallel refractive index that can be set within the range of 0-100. The rectangular waveguides on both sides integrated with the antenna serve as the microwave input and output structure. Preferably, the antenna has a reflection coefficient and transmission coefficient of less than -10dB and a parallel refractive index of 4.0 at 2.45 GHz. Furthermore, the antenna adopts a dual-port structure with a self-cleaning gas adsorption function, requiring no aging after experimentation. It is mainly used in high average power microwave systems, especially in the low-clutter wave drive of 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 antenna's performance, reflection coefficient, field strength distribution, and parallel refractive index. After the antenna is fabricated and shaped, it can be debugged to meet engineering requirements, and the experimental test results are good.

[0034] like Figure 4 The figure shows the S-parameter diagram of the outer antenna of the tokamak in this embodiment, including simulation and experimental results. Its center operating frequency is 2.45 GHz. The S-parameters (including reflection coefficient (S11) and transmission coefficient (S12 or S21)) at this point are all less than -10 dB. About 95% of the microwave energy is radiated into the air, and about 5% of the energy is emitted from the ports of the two feed waveguides 1. The bandwidth is 10 MHz.

[0035] like Figure 5 The figure shows the parallel refractive index diagram of the outer antenna of the tokamak in this embodiment. Its center operating frequency is 2.45 GHz, and the parallel refractive index at this point is 4.0. The figure shows that the antenna has excellent directivity, and the simulation and experimental results are basically consistent. Slight variations in these results are allowed depending on the processing materials (gold, silver, copper, aluminum, stainless steel, etc.).

[0036] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A tokamak outer antenna, characterized in that: The device includes a feed waveguide, a brim, sub-waveguides, and a metal base. The metal base is W-shaped, with each end connected to the lower surface of a feed waveguide. The opposite sides of two feed waveguides are connected to a brim. Several sub-waveguides are evenly spaced on the upper surface of the metal base. The height of each sub-waveguide does not exceed the height of the feed waveguide. One feed waveguide is used as a microwave input port, and the other feed waveguide is used as a microwave output port. The feed waveguide has a rectangular opening, and the bottom surface of the feed waveguide is flush with the top surface of the metal base. The starting height of the sub-waveguide is not higher than the bottom surface of the feed waveguide. The brim is inverted U-shaped and symmetrically connected to the feed waveguides at both ends. The top surface of the brim is flush with the top surface of the feed waveguide, and both sides are right-angled triangles. Both sides are connected to the sidewalls of the feed waveguide.

2. The tokamak outer antenna according to claim 1, characterized in that: The base plate of the metal base is arched, and two stepped surfaces are symmetrically arranged on the base plate. Both ends of each stepped surface are flat. The vertical lengths of the sub-waveguides arranged on the base plate are the same and are all 0mm-100mm.

3. The tokamak outer antenna according to claim 2, characterized in that: The height of each step on the stepped surface is 0mm-100mm; the length of the feed waveguide is at least 100mm and the width is at least 20mm; the length of the brim along the microwave conduction direction is at least 20mm.

4. The tokamak outer antenna according to claim 1, characterized in that: The radiating gaps between adjacent sub-waveguides are filled with air or vacuum, and there are at least 16 radiating gaps. The width of each radiating gap is 0 mm to 100 mm, and the depth of each radiating gap is 0 mm to 100 mm.

5. The tokamak outer antenna according to claim 4, characterized in that: The number of radial slits is 28, and the depth is 28 mm.

6. The tokamak outer antenna according to claim 1, characterized in that: The number of sub-waveguides is 0-100, and the thickness of the sub-waveguides is 0mm-100mm.

7. The tokamak outer antenna according to claim 6, characterized in that: The number of sub-waveguides is 27, the thickness of the sub-waveguides is 1.5 mm, and the spacing between them is 5 mm.

8. The tokamak outer antenna according to claim 1, characterized in that: The feed waveguide, the cap brim, the sub-waveguide, and the metal base are made of copper, aluminum, iron, or stainless steel.

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