阅读说明：本技术 一种降低加热天线射频鞘的电流补偿装置 (Current compensation device for reducing heating antenna radio frequency sheath ) 是由 宋云涛 李家豪 杨庆喜 陈肇玺 徐皓 陈仕琳 于 2021-05-17 设计创作，主要内容包括：本发明公开一种降低加热天线射频鞘的电流补偿装置,包括支撑箱体,支撑箱体包括接地背板和窗口,窗口包括端部底板和侧挡板,接地背板的上下两端分别设置有端部底板,接地背板的左右两端分别设置有侧挡板,两个侧挡板的中间位置设置有极向隔板,极向隔板与端部底板互为垂直设置,窗口设计成倾角为θ的平行四边形,倾角θ和托克马克总磁场与环向间夹角θ相同,本发明在高天线功率馈入时,一方面通过将支撑箱体底板绝缘来消除其表面高强度的环向射频电流密度,另一方面对极向隔板部分绝缘来阻断流经法拉第屏蔽的环向电流,能够有效削弱形成射频鞘电势的平行电流虚部,使天线运行时的射频鞘电势峰值大大降低。(The invention discloses a current compensation device for reducing a heating antenna radio frequency sheath, which comprises a supporting box body, wherein the supporting box body comprises a grounding back plate and a window, the window comprises an end bottom plate and side baffles, the upper end and the lower end of the grounding back plate are respectively provided with the end bottom plate, the left end and the right end of the grounding back plate are respectively provided with the side baffles, a polar direction clapboard is arranged at the middle position of the two side baffles, the polar direction clapboard and the end bottom plate are mutually and vertically arranged, the window is designed into a parallelogram with an inclination angle theta, and the inclination angle theta and a Tokamak total magnetic field have the same included angle theta with the annular direction. The peak value of the radio frequency sheath potential when the antenna operates is greatly reduced.)

1. The utility model provides a reduce current compensation arrangement who heats antenna radio frequency sheath, a serial communication port, including the supporting box, the supporting box includes ground connection backplate (1) and window, the window includes end bottom plate (5) and side shield (4), the upper and lower both ends of ground connection backplate (1) are provided with respectively end bottom plate (5), both ends are provided with respectively about ground connection backplate (1) side shield (4), two the intermediate position of side shield (4) is provided with utmost point to baffle (8), utmost point to baffle (8) with end bottom plate (5) each other are perpendicular setting, the window designs into the parallelogram that the inclination is theta, inclination theta and ask gram total magnetic field are the same with hoop contained angle theta between.

2. The current compensation device for reducing the radio frequency sheath of the heating antenna is characterized by further comprising a Faraday shield (7), wherein one end of the Faraday shield (7) is connected with the side baffle (4), the other end of the Faraday shield (7) is connected with the polar partition (8), the joint of the Faraday shield (7) and the polar partition (8) is coated with a ceramic insulating layer, and the end bottom plate (5) is also coated with the ceramic insulating layer (9).

3. A current compensating device to reduce the rf sheath of a heated antenna as claimed in claim 2, characterised in that the angle of inclination of the faraday shield (7) is the same as the angle of inclination of the window.

4. A device for compensating for a reduction in the current flowing through the rf sheath of a heating antenna according to claim 2, wherein the insulating ceramic layer (9) is made of a high temperature resistant low conductivity ceramic material with a skin depth greater than the skin depth.

5. A current compensating device for reducing the rf sheath of a heating antenna according to claim 1, further comprising 4 current strips (6), wherein the 4 current strips (6) are fixedly connected to the inside of the supporting box in a 2 x 2 polar distribution.

6. The current compensation device for reducing the radio frequency sheath of the heating antenna is characterized by further comprising a transverse partition plate (3), wherein the transverse partition plate (3) and the end bottom plate (5) are arranged in parallel, are arranged perpendicular to the polar partition plate (8) and are fixedly arranged in the middle of the polar partition plate (8).

7. The current compensation device for reducing the radio frequency sheath of a heating antenna as claimed in claim 1, wherein the side baffle (4) extends in a circumferential widening along the extension direction of the faraday shield, and the inner side of the side baffle is provided with a groove.

8. The current compensation device for reducing the heating antenna radio frequency sheath of claim 1, characterized in that the side baffle (4) is fixedly provided with a side limiter (2) at the outer side.

Technical Field

The invention relates to the technical field of magnetic confinement nuclear fusion tokamak auxiliary heating equipment, in particular to a current compensation device for reducing a radio frequency sheath of a heating antenna.

Background

The Tokamak device is an important device for magnetic confinement nuclear fusion research at present and fusion energy development in the future, and Ion Cyclotron Resonance Heating (ICRH) and Current Drive (CD) are important means for obtaining stable and high-parameter plasma by the Tokamak device. The large-scale magnetic confinement nuclear fusion devices at home and abroad are all provided with ion cyclotron heating systems, and the heating power of the ion cyclotron heating antenna can reach dozens of megawatts (more than or equal to 20MW) on future fusion reactors. However, the rf sheath formed under the ion cyclotron drive causes a strong interaction between the plasma and the boundary material, which causes a series of negative effects and problems such as impurity sputtering, boundary power loss, hot spot, etc., not only changing the boundary plasma parameters and affecting the plasma performance, but also causing damage to the material and shortening the material lifetime.

Theoretical studies have shown that the rf sheath is driven by rf waves and is formed mainly on the surface of the plasma-facing material, including the antenna's box and the faraday shield, with the supporting and protecting parts of the antenna structure. The sheath potential of the heating and current driven RF sheath is typically much larger than that of the suspended sheath due to the action of the wavefield, since electrons respond much more strongly to the RF wavefield than ions, thus increasing the loss of electrons, causing the sheath dc potential to be elevated, i.e., the "RF sheath rectification effect". Ions are accelerated under the action of high potential difference of the radio frequency sheath, obtain high energy and bombard the surface of a material or generate E & ltB & gt drift transport under the combined action of the ions and a main magnetic field, so that strong impurity sputtering is caused. In addition, ions are accelerated under the action of the radio frequency electric field and collide with the material, so that energy is transferred from the radio frequency field to the surface of the material, and parasitic power loss (sheath power loss) is caused, which is one of the main factors causing the power loss of radio frequency waves at the boundary. The loss of rf power at the boundary can cause a high-density region and a strong rf sheath to be formed locally on the antenna or other materials such as the first wall, resulting in "hot spots" on the local heat flow deposition of the materials.

Based on the research on the antenna structure radio frequency sheath of EAST Turke Mark B port 2 x 2 current band, the peak position of the frequency sheath potential and the release of metal impurities are positioned at the top and the bottom of the polar limiter at two sides of the antenna supporting box body. The essence of the rf sheath potential build up is due to the presence of parallel currents generated on the metallic structure of the antenna support and protection. Therefore, a new method is needed to reduce the parallel current fundamentally so as to achieve the purpose of reducing the integral potential and impurity flux of the radio frequency sheath.

Disclosure of Invention

Aiming at improving a series of negative effects and problems of impurity sputtering, boundary power loss, hot spot and the like caused by the potential of a radio frequency sheath on the surface of an antenna facing plasma during ion cyclotron heating and current driving, the invention designs a novel current compensation device for reducing a radio frequency sheath, and the whole parallel current density is reduced and a small loop is formed by utilizing the blocking and compensation of local current, so that the aim of reducing the integral potential and the impurity flux of the radio frequency sheath is fulfilled.

The invention provides a current compensation device for reducing a heating antenna radio frequency sheath, which comprises a supporting box body, wherein the supporting box body comprises a grounding backboard and a window, the window comprises an end bottom plate and side baffles, the upper end and the lower end of the grounding backboard are respectively provided with the end bottom plate, the left end and the right end of the grounding backboard are respectively provided with the side baffles, a polar direction partition plate is arranged at the middle position of the two side baffles, the polar direction partition plate and the end bottom plate are mutually and vertically arranged, the window is designed into a parallelogram with an inclination angle theta, the inclination angle theta is the same as the included angle theta between a Tokamak total magnetic field and the ring direction, and the inclination angle refers to the angle between the window and the horizontal ground.

Specifically, an antenna window formed by surrounding of bottom plates at the upper end part and the lower end part of the antenna supporting box body and the left side baffle and the right side baffle is in a parallelogram shape, the angle of inclination of the window and a Faraday shielding is consistent with the angle theta between a total magnetic field of a Tokamak and a ring direction, and the inclined parallelogram window is designed by abandoning a traditional rectangular window box body so as to reduce the intersection part of a long magnetic field line and a box body structure to the maximum extent to improve the integral symmetry of the radio frequency sheath electric potential and reduce the radio frequency sheath electric potential.

The improved faraday shield comprises a faraday shield, wherein one end of the faraday shield is connected with the side baffle, the other end of the faraday shield is connected with the polar partition, a ceramic insulating layer is coated at the joint of the faraday shield and the polar partition, and the insulating ceramic layer is also coated on the end bottom plate.

Specifically, the surface of the bottom plate at the end part of the supporting box body is coated with high-temperature-resistant low-conductivity ceramics so as to eliminate high-intensity parallel direction induced radio frequency current (the total magnetic field direction of the Tokamak) gathered at the surface; insulating ceramic coating is carried out on the position where the polar direction clapboard is fixedly connected with the Faraday shield so as to block parallel current which flows through the Faraday shield and penetrates through the support box body under the driving of alternating magnetic flux; the mode for eliminating the radio frequency current induced in the parallel direction is to fundamentally reduce the current source term in the radio frequency sheath integral potential Helmholtz equation.

A further improvement is that the angle of inclination of the faraday shield and the angle of inclination of the window are the same.

The further improvement is that the insulating ceramic layer is made of high-temperature-resistant low-conductivity ceramic material with the skin depth larger than that of the skin.

The further improvement lies in that still include 4 electric current strips, 4 electric current strips are in 2 x 2 distribution of utmost point and are fixed connection in the inside of supporting box. The polar distribution refers to the poloidal direction perpendicular to the horizontal ground.

The improved structure is characterized by further comprising a transverse clapboard, wherein the transverse clapboard and the end bottom plate are arranged in parallel and are perpendicular to the polar clapboard, and the transverse clapboard and the polar clapboard are fixedly arranged in the middle of the polar clapboard.

The side baffle extends in a circumferential widening manner along the extension direction of the Faraday shield, and the specific width depends on the size of a window where the antenna is arranged; the inner side surface of the side baffle is provided with a groove, namely, the side baffle is hollowed out to a certain extent. The side baffle of the antenna supporting box body is annularly widened and extended to increase the polar radio frequency current on the surface of the box body so as to form polar dredging compensation, and the specific width is determined according to the size limit of a window for mounting the antenna; the inner wall surface of the widened side baffle of the antenna supporting box body is provided with a groove, so that the space in the box body is increased to reduce the reactance of the antenna, and better power transmission is obtained.

The improvement is that a side limiter is fixedly arranged on the outer side of the side baffle.

Compared with the prior art, the invention has the beneficial effects that:

1. when high antenna power is fed in, on one hand, the annular radio frequency current density with high strength on the surface of the supporting box body is eliminated by insulating the bottom plate of the supporting box body, and on the other hand, the annular current flowing through the Faraday shield is blocked by insulating the opposite polar partition part, so that the parallel current imaginary part forming the radio frequency sheath potential can be effectively weakened, and the radio frequency sheath potential peak value during the operation of the antenna is greatly reduced.

2. The design of the inclined antenna window and the Faraday shield can reduce the intersection of the Tork Mark total magnetic field line and the structure to the maximum extent under the typical heating and driving phases of the antenna, and meet the integral symmetry of the radio frequency sheath potential, thereby reducing the radio frequency sheath potential; the annular side baffle plate which is slightly wider and provided with the slot on the inner wall surface can increase the polar radio frequency current to form compensation and reduce the reactance of the antenna during operation.

Drawings

The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

FIG. 1 is a front view of a front end component of a heating antenna in accordance with one embodiment of the present invention;

FIG. 2 is a schematic axial view of a support housing according to an embodiment of the present invention;

FIG. 3 is a comparison graph of simulation calculations for an RF sheath at the front end of an antenna in accordance with one embodiment of the present invention;

wherein: 1. a grounded back plate; 2. a side limiter; 3. a diaphragm plate; 4. a side dam; 5. an end floor; 6. a current strip; 7. a Faraday shield; 8. a polar separator; 9. and an insulating ceramic layer.

Detailed Description

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, so to speak, as communicating between the two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art. The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

The current compensation device for reducing the radio frequency sheath is suitable for heating the antenna under the high power state, especially aiming at the typical dipole heating phase and the current driving phase.

For the surface of the supporting box body with high parallel current density, the current density is very small compared with the current strip used for radiation, and the radiation power spectrum distribution of the antenna and the coupling performance of the antenna are not changed.

Referring to the attached figure 1, the current compensation device for reducing the radio frequency sheath of the heating antenna can effectively reduce the electric field component and the imaginary part current component of the surface of a component, facing the plasma, of the antenna, which are parallel to the total magnetic field direction of the Tokamak, has the characteristic of low radio frequency sheath potential, and comprises a Faraday shield 7 of the antenna, a side limiter 2, a current strip 6, a diaphragm 3 and a supporting box body; the supporting box body is formed by connecting a rear side grounding back plate 1, bottom plates 5 at the upper end part and the lower end part, left and right side baffle plates 4 and a polar direction baffle plate 8; the four current strips are fixedly connected inside the supporting box body and are arranged in a 2 x 2 polar direction; the side limiters 2 are positioned at two sides of the side baffle 4 of the supporting box body; one end of the Faraday shield 7 is connected with the side baffle of the supporting box body, and the other end of the Faraday shield is fixed on an insulating ceramic layer 9 with low conductivity of the polar partition plate in the middle of the supporting box body so as to block the annular current flowing through the Faraday shield.

In a Tork Mark plasma environment, a suspension sheath is formed on the surface of a heating antenna structure, and when the antenna is heated or driven by current, the strength of a radio frequency sheath is greatly increased due to the alternation of magnetic flux (d phi/dt); when the antenna front-end structure is inconsistent with the direction of the total magnetic field, charged particles can bombard the front-end structure to cause a series of negative effects and problems such as impurity sputtering, boundary power loss, hot spots and the like; according to the current compensation method for reducing the heating antenna radio frequency sheath, the window of the supporting box body is designed into a parallelogram, the inclined angle of the window and the Faraday shielding is consistent with the included angle theta between the total magnetic field of the Tokamak and the ring direction, the intersection part of the total magnetic field line and the box body structure is effectively reduced, the integral symmetry of the radio frequency sheath potential can be improved, the radio frequency sheath potential is reduced, and meanwhile the bombardment of charged particles moving along the total magnetic field line is reduced.

The end bottom plate of the heating antenna supporting box body usually forms high-strength radio frequency current in the parallel direction due to radio frequency induction, so that high radio frequency potential at the position is caused; the bottom plates of the upper end part and the lower end part of the supporting box body are coated with high-temperature-resistant low-conductivity ceramic materials with the depth larger than the skin depth so as to eliminate induced parallel current, and the radio frequency sheath is reduced fundamentally by reducing a current source item in a radio frequency sheath integral potential Helmholtz equation.

The side baffle of the antenna supporting box body extends in a circumferential widening way, so that the current intensity of the polar direction of the surface of the box body is increased to form current compensation, the resistance is lower when the width is larger, but the specific width is determined according to the size limit of a window for mounting the antenna; fig. 2 is an axonometric view of the supporting box mentioned in the device of the invention, the inner wall surface of the widened side baffle is provided with a groove to increase the space in the box to reduce the reactance of the antenna and obtain better power transmission, the shape of the groove is approximately consistent with the arc trend of the current band direction, the depth of the groove is determined by the widening degree of the side baffle and is 10-15cm less than the thickness of the side baffle.

In fig. 2, the position of the fixed connection between the interior of the polar partition and the faraday shield is coated with a low-conductivity ceramic layer 9, the width of which is slightly larger than the radial dimension of the faraday shield, for breaking the loop driven by the induced electromotive force, and the plurality of loops are formed by the alternating magnetic flux in the area enclosed by the faraday shield and the supporting box; and the outermost layer of the polar separator is grounded by using a conductive material to form polar and radial dredging compensation of current.

FIG. 3 is a comparison chart of simulation calculation of the RF sheath at the front end of the antenna before and after the current compensation device for reducing the RF sheath of the heating antenna is adopted, when the high-power heating antenna operates at a typical heating phase and a driving phase, the blocking of the annular current is eliminated and the polar current is dredged and compensated to form a local small loop, so that the potential of the RF sheath is reduced; meanwhile, the current density on the supporting box body and the Faraday shield is very small compared with a current strip for radiation, the radiation power spectrum distribution and the coupling performance of the antenna cannot be changed, and calculation shows that when the EAST device B window heating antenna adopts the current compensation device for reducing the radio frequency sheath, the parallel power spectrum peak value of the antenna is almost unchanged.

In the drawings, the positional relationship is described for illustrative purposes only and is not to be construed as limiting the present patent; it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.