Hemispherical inductively coupled plasma source with adjustable density distribution

Abstract

The invention relates to a hemispherical inductively coupled plasma source with adjustable density distribution, and belongs to the technical field of plasma generating devices. Comprising an upper cover body, a lower cover body, a flange and a coil, the upper cover body, the lower cover body and the flange are sequentially and coaxially arranged from top to bottom, a cavity is formed between the upper cover body and the lower cover body, a connector pipe is arranged on the side face of the flange, the cavity is communicated with the connector pipe, and the coil is arranged on the outer side of the cavity. The method is mainly used in the field of antenna radiation performance regulation and control, and effective regulation and control of antenna radiation characteristics can be realized.

Description

Technical Field

[0001] The invention relates to a hemispherical inductively coupled plasma source with adjustable density distribution, belonging to the technical field of plasma generating devices. Background Art

[0002] In recent years, the use of low-temperature gas discharge plasma sources to regulate electromagnetic waves has attracted the attention of more and more scholars. Antennas are the carriers of transmitting and receiving signals in wireless communication systems. The performance of antennas plays an extremely important role in the quality of communication signals. Therefore, how to optimize the performance of antennas has important research value. Among them, the gain of the antenna is the most important key parameter, which largely determines the quality of the antenna. The higher the gain of the antenna, the larger its effective communication coverage range and the longer the transmission signal coverage distance.

[0003] With the needs of aerospace development, miniaturized, lightweight, ultra-wideband, high-gain, and fully polarized antennas have become the mainstream of development. Ultra-wideband antennas are relatively easy to implement, but miniaturization and high gain are contradictory. The traditional approach uses a compromise solution, which is to increase the volume of the antenna to obtain a relatively high gain within an acceptable range. This results in the limitation of the volume that can be reduced while ensuring the high gain of the antenna, affecting its miniaturization and lightweight design. Therefore, how to ensure that the antenna has a high gain while achieving miniaturization is a problem worthy of attention. In recent years, scholars have proposed subwavelength plasma enhanced microwave electromagnetic radiation technology, which provides a new idea for solving the contradiction between miniaturization and high gain. The introduction of plasma in this technology makes the passive antenna gain improvement a relatively independent modular method that can ignore other antenna parameters. The subwavelength plasma enhancement method can effectively decouple the contradiction between miniaturization and high gain.

[0004] In terms of articles, Laquerbe V, Pascaud R, Laffont A et al. published an article entitled "Towards antenna miniaturization at radio frequencies using plasma discharges" in the journal "Physics of Plasmas" in 2019, with volume number 26, issue number 3, and article number 033509. In their technical solution, the spatial distribution of plasma density cannot be directionally regulated - part of the uniformity requires the realization of non-uniform distribution with specific morphology; Brcka J et al. published an article entitled "Investigation of large-area multicoil inductively coupled plasma sources using three-dimensional fluid model" in 2016, published in the journal "Japanese Journal of Applied Physics", volume number 55, issue number 6, article number 065201. The technical solution described in it is to use a simulation method to compare the radial density and angular density distribution of distributed multi-coil ICP and integrated multi-coil ICP discharge devices; the plasma density in the inductively coupled plasma discharge chamber is changed by adjusting the current, frequency, phase, power and other parameters of the distributed multi-coil ICP; however, the technical solution described in it lacks a control strategy for how to regulate the spatial distribution of plasma density; Laquerbe V, Pascaud R et al. published an article entitled "Towards antenna miniaturization at radio frequencies using plasma discharges" in 2019, published in the journal "Physics of Plasmas", volume number 26, article number 033509. Its technical solution is to discharge in a hemispherical structure chamber by using a bottom plane incense coil excitation method. Its bottom plane incense coil excitation method can only adjust the density of the plasma, but cannot change the spatial distribution of the plasma density in the chamber.

[0005] In terms of patents, the publication number is CN106025546B, and the name of the invention is a device for enhancing the electromagnetic radiation of a miniaturized omnidirectional antenna using plasma modulation. Its technical solution uses a cylindrical inductively coupled plasma source to generate non-uniform plasma, and it is impossible to achieve the regulation of the spatial distribution of plasma density. The publication number is CN115863967A, and the name of the invention is a radiation enhancement method based on non-uniform plasma. Its technical solution proposes to use a non-uniform plasma spherical structure to cover an electric small antenna to achieve the enhancement of the radiation capacity of the electric small antenna by non-uniform plasma. The non-uniformity proposed in its technical solution is a monotonous non-uniform plasma, and it is impossible to achieve non-uniform plasma in a specific spatial environment. The publication number is CN118175716A, and the name of the invention is a parameter-adjustable sub-wavelength thin layer plasma generator and its use method. Its technical solution uses a dual-frequency driven discharge method to regulate the density of plasma discharge, but lacks regulation of the spatial distribution of plasma density. The publication number is CN104981086B, and the invention is called Enhanced RF Inductively Coupled Plasma Discharge Device. Its technical solution is to use an external spiral coil to generate plasma for a cylindrical inductively coupled plasma source, which can generate high-density, large-area, uniform and stable plasma. However, there are end caps on both sides of the cylindrical discharge chamber structure of the external spiral coil, which cannot achieve omnidirectional gain for the small antenna, and the end cap structures on both sides will also affect the gain of the measurement antenna.

[0006] Exploring the antenna radiation characteristics of subwavelength plasma and realizing the effective decoupling of antenna miniaturization and high gain under non-uniform plasma coating have important application value in the fields of information network smart base station and intelligent control of aircraft electromagnetic environment. At present, most scholars use low-temperature inductively coupled plasma to provide a matching plasma environment for modulation of antenna radiation enhancement characteristics. There are two main types of RF inductively coupled plasma according to the winding method of the coil: one is a planar coil inductively coupled plasma source, that is, a planar coil similar to the shape of a mosquito coil on the quartz window at the top of the discharge chamber; the other is a cylindrical spiral coil inductively coupled plasma source, that is, a spiral-like coil is wound on the side wall of the cylindrical quartz discharge chamber. For the plasma environment of antenna radiation characteristic modulation, it is necessary not only to generate a relatively stable plasma, but also to regulate the spatial distribution of the plasma and sense the key parameters. Therefore, the planar coil inductively coupled plasma source and the cylindrical plasma source cannot meet the research on antenna radiation characteristic modulation. It is urgent to design an inductively coupled plasma source that can not only generate stable plasma, but also regulate the spatial distribution of plasma density and sense key parameters.

[0007] Therefore, there is an urgent need for a hemispherical inductively coupled plasma source with adjustable density distribution to solve the above technical problems. Summary of the invention

[0008] In order to explore the antenna radiation characteristics of subwavelength plasma, solve the key problem that traditional metal antennas cannot meet high gain and miniaturization, and develop and improve the influence of plasma parameters on radiation enhancement under non-uniform plasma coating, the mechanism and theoretical system, it is necessary to provide a hemispherical inductively coupled plasma source with adjustable density distribution to achieve directional regulation of the density distribution in the plasma region space. The present invention provides a matching plasma environment for antenna radiation characteristic modulation, which is suitable for plasma generating devices for the interaction of electromagnetic waves and plasma, and can achieve plasma density spatial distribution regulation (directional non-uniformity and symmetrical uniformity) for antennas under different complex airspace conditions. Solve the multiple limitations of existing plasma generating devices that cannot adjust density distribution, electron density, and background gas pressure. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0009] The technical solution of the present invention:

[0010] The technical solution adopted by the present invention to solve the above problems is: a hemispherical inductively coupled plasma source with adjustable density distribution, comprising an upper cover body, a lower cover body, a flange and a coil, wherein the upper cover body, the lower cover body and the flange are coaxially arranged in sequence from top to bottom, a chamber is formed between the upper cover body and the lower cover body, an interface pipe is arranged on the side of the flange, the chamber is connected to the interface pipe, and a coil is arranged on the outside of the chamber.

[0011] Preferably, the upper cover body and the lower cover body are made of quartz, the upper part of the upper cover body and the lower cover body both have a hemispherical shell, the two hemispherical shells are concentrically arranged, and the lower edge of the arc-shaped shell has a ring edge.

[0012] Preferably, one connection port is arranged in the middle of the upper cover body, or a plurality of connection ports are arranged equidistantly in the circumferential direction on the upper part of the upper cover body, and the connection port is communicated with the chamber.

[0013] Preferably, the flange is made of stainless steel, and four interface pipes are evenly arranged on the side of the flange.

[0014] Preferably: the coil includes a spiral coil and / or an incense coil, the spiral coil is arranged above the upper cover body, the spiral coil and the upper cover body can be fixed by insulating tape, the spiral coil is arranged along the outer wall of the upper cover body, so that the vertical distances from different positions of the spiral coil to the outer wall of the cover body are equal, the incense coil is arranged below the lower cover body, and the incense coil and the lower cover body are coaxially arranged.

[0015] Preferably: a coil installation groove is processed at the bottom of the annular edge of the lower cover body, and an incense coil is installed in the coil installation groove.

[0016] Preferably: it also includes a lower pressure plate, an upper pressure plate and bolts, the lower pressure plate and the upper pressure plate are annular, the upper pressure plate is arranged on the upper side of the annular edge of the upper cover body, a part of the bolts that are evenly arranged circumferentially (a sealing groove is provided, and 12 polytetrafluoroethylene bolts are used to evenly seal the chamber - an O-ring is used for sealing between the flange and the cover body, and a polytetrafluoroethylene pad is used for protection between the cover body and the pressure cover) pass through the upper pressure plate and the upper threaded connection of the flange, and the annular edge of the upper cover body is pressed between the upper pressure plate and the flange, the lower pressure plate is arranged on the lower side of the annular edge of the lower cover body, and another part of the bolts that are evenly arranged circumferentially pass through the lower pressure plate and the lower threaded connection of the flange, and the annular edge of the lower cover body is pressed between the lower pressure plate and the flange, and the relative positions of the lower pressure plate, the upper pressure plate and the flange are fixed.

[0017] Preferably, a sealing groove is processed at the connection between the upper cover body and the flange, and at the connection between the flange and the lower cover body, and a sealing O-ring is arranged in the sealing groove.

[0018] Preferably: the arc shell is hemispherical, the inner diameter of the arc shell of the upper cover is 200mm, and the outer diameter of the arc shell of the lower cover is 90mm; the incense coil is a four-turn coil structure with a pitch of 13.75cm, and the spiral coil is a four-turn spiral coil structure with a pitch of 13.75cm.

[0019] Preferably: it also includes a vacuum system, a matcher, a radio frequency source and a diagnostic system, the vacuum system is connected to the interface tube, the two poles of the coil, the matcher and the radio frequency source are electrically connected in sequence, and the diagnostic system is connected to the connection port.

[0020] The present invention has the following beneficial effects:

[0021] 1. Compared with the traditional planar inductively coupled plasma discharge structure, the hemispherical chamber structure of the present invention has an advantage in radial uniformity of discharge; and the double-hemispherical structure can greatly improve the uniformity of the plasma in the discharge chamber through a simple and ingenious structural design; the double-hemispherical structure can not only improve the uniformity of the plasma in the discharge chamber, but also regulate the thickness of the plasma sheath, and can simulate the complex plasma sheath environment in near space.

[0022] 2. Compared with the traditional cylindrical inductively coupled plasma discharge structure, the hemispherical chamber of the present invention can improve the poor radial uniformity and the disadvantage of being unable to adjust the plasma spatial distribution; the spiral coil and the incense coil excitation method can not only modulate the plasma spatial distribution in the stagnation area of ​​the plasma sheath head, but also increase the plasma density at the same power, thereby achieving a plasma density of 10 10~10 12 cm -3 Adjustable; that is, adjustable thickness and adjustable density distribution.

[0023] 3. Compared with the traditional inductively coupled plasma discharge structure, the present invention adopts a hemispherical structure with a branch pipe in conjunction with a mobile probe diagnostic system, which can not only realize real-time diagnosis of the spatial distribution and parameters of the plasma, but also can achieve a plasma environment that is modulated and matched with the radiation characteristics of the electric small antenna by adjusting the working mode of the four-turn spiral coil and the incense coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a stereogram of a hemispherical inductively coupled plasma source with adjustable density distribution;

[0025] Figure 2 It is an exploded view of a hemispherical inductively coupled plasma source with adjustable density distribution;

[0026] Figure 3 It is a bottom view of a hemispherical inductively coupled plasma source with adjustable density distribution;

[0027] Figure 4 yes Figure 3 Middle AA section view;

[0028] Figure 5 It is a schematic diagram of the structure of a hemispherical inductively coupled plasma source with adjustable density distribution and double branches;

[0029] Figure 6 It is a schematic diagram of the structure of a hemispherical inductively coupled plasma source plasma environment space ground experimental device with adjustable density distribution;

[0030] Figure 7 It is a schematic diagram of the diagnosis of a ground experimental device for a hemispherical inductively coupled plasma source environment with adjustable density distribution;

[0031] Figure 8 This is the simulation diagram of the spiral coil being excited alone;

[0032] Fig. 9 This is a simulation diagram of the incense coil being excited individually;

[0033] Fig.10 This is a simulation diagram of a double coil (spiral coil and incense coil working at the same time);

[0034] Fig.11 This is the experimental diagnostic data diagram of the probe's measured discharge power of 70W and 243W;

[0035] Fig.12 This is a graph of experimental data of plasma density at different powers in the radial direction of the central axis.

[0036] In the figure: 1-upper cover, 2-lower cover, 3-spiral coil, 4-incense coil, 5-flange, 6-lower pressure plate, 7-upper pressure plate, 8-bolt, 11-connecting port, 21-coil installation slot, 51-interface pipe. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0038] Specific implementation method 1: Combination Figure 1-12 The present embodiment is described. The ground simulation device for the near-space plasma sheath head environment of the present embodiment comprises an upper cover body 1, a lower cover body 2, a flange 5 and a coil. The upper cover body 1, the lower cover body 2 and the flange 5 are coaxially arranged in sequence from top to bottom, and a chamber is formed between the upper cover body 1 and the lower cover body 2. An interface pipe 51 is arranged on the side of the flange 5, and the chamber is connected to the interface pipe 51. A coil is arranged on the outside of the chamber.

[0039] The upper cover body 1 and the lower cover body 2 are made of colorless quartz insulating glass. The upper parts of the upper cover body 1 and the lower cover body 2 are both hemispherical shells. The two hemispherical shells are concentrically arranged, and the lower edges of the hemispherical shells have an annular edge.

[0040] A connection port 11 is arranged at the top of the upper cover body 1, or a plurality of connection ports 11 are arranged equidistantly in the circumferential direction at the upper part of the upper cover body 1, and the connection port 11 is connected to the chamber; the use of a spherical cover body chamber can improve the uniformity of the plasma space in the radial direction, and can achieve a more uniform plasma; the connection port 11 of the upper cover body can diagnose the plasma space distribution and plasma parameters in real time;

[0041] The material of the flange 5 is 304 stainless steel, and four interface pipes 51 are evenly arranged on the side of the flange 5;

[0042] The coil includes a spiral coil 3 and / or a coil 4, wherein the spiral coil 3 is arranged above the upper cover 1, and the spiral coil 3 and the upper cover 1 can be fixed by an insulating tape, and the spiral coil 3 is arranged along the outer wall of the upper cover 1, so that the vertical distances from different positions of the spiral coil 3 to the outer wall of the cover 1 are equal, and the coil 4 is arranged below the lower cover 2, and the coil 4 is coaxially arranged with the lower cover 2;

[0043] The invention provides a density-adjustable hemispherical inductively coupled plasma generating device for antenna radiation characteristic modulation. The main generating mode is an inductively coupled plasma source ICP. The radio frequency ICP source can generate plasma without the effect of an external magnetic field. The device has a simple structure, reduces the cost of use, and is easy to operate. The plasma source system comprises: a double coil (inductively coupled plasma source), a radio frequency power supply and a matcher. A double coil excitation inductively coupled discharge technical scheme is designed. The upper coil is a four-turn spiral coil structure, and the lower coil is a four-turn incense coil structure. The upper and lower double coil discharge powers can be controlled separately by changing the coil connection mode to adjust the plasma density spatial distribution. When used separately, the double coil can generate a large amount of plasma. When the four-turn spiral coil is working, the plasma it generates is mainly concentrated in the top area of ​​the chamber; when the four-turn incense coil is used alone, the plasma it generates is mainly concentrated in the bottom area of ​​the chamber; when the four-turn spiral coil and the incense coil are used in series, the plasma it generates is mainly concentrated in the middle top area of ​​the chamber, and the plasma density is improved compared with the single coil operation; when the four-turn spiral coil and the incense coil are used in parallel, the spatial distribution of the plasma density changes with the increase of power; therefore, the dual-coil coordinated control method can be used, which can not only improve the plasma density under the same working conditions, but also realize the regulation of the spatial distribution of the plasma density;

[0044] Compared with the spiral coil structure, the plasma spatial distribution of the incense coil excitation discharge structure is mainly concentrated near the bottom area of ​​the chamber, and the plasma density is also low. The uniformity of the radial plasma density distribution is poor. This is mainly due to the fact that the excitation method of the coil is inductively coupled discharge. Therefore, in order to distinguish the traditional incense coil excitation method, the pitch of the coil is selected as 13.75cm through simulation structure analysis, which can greatly optimize the uniformity of the plasma density spatial distribution and generate a relatively uniform plasma source in the hemispherical discharge chamber; compared with the excitation of the spiral coil and the incense coil, the double coil excitation method is used for excitation, which can greatly improve the uniformity of the plasma spatial distribution in the discharge chamber. Under the same working conditions, the plasma electron density can be increased, and the plasma density can be achieved at 10 10 ~10 12 cm -3 The magnitude range distribution is adjustable;

[0045] The bottom of the annular edge of the lower cover 2 is processed with a coil installation groove 21, and the coil installation groove 21 is installed with a coil incense coil 4; the present invention provides a plasma environment that matches the antenna radiation characteristic modulation, and it is necessary to realize the directional control of the density distribution of the plasma space; compared with the traditional columnar and coil incense type ICP structure, the device adopts a hemispherical discharge chamber structure, uses a four-turn spiral coil and the coil incense coil for coordinated control, and can not only realize the plasma density within 10 10 ~10 12 cm -3 The magnitude range is adjustable, and the spatial distribution of plasma density can also be regulated; the four-turn incense coil used in the device works in an air environment, has no plasma coating, and uses a uniform four-turn structure to couple to a vacuum Ar discharge chamber through radio frequency excitation to generate plasma; the four-turn spiral coil used in the device also works in an air environment, and generates plasma through inductive coupling of an RF power supply; compared to the working environment of the antenna, an antenna works in an argon plasma environment, and the antenna of the device of the present invention works in an air environment and discharges through the inductive coupling principle of the radio frequency power supply;

[0046] It also includes a lower pressing plate 6, an upper pressing plate 7 and bolts 8, the lower pressing plate 6, the upper pressing plate 7 and the bolts 8 are made of polytetrafluoroethylene, the lower pressing plate 6 and the upper pressing plate 7 are annular, the upper pressing plate 7 is arranged on the upper side of the annular edge of the upper cover body 1, a part of the circumferentially uniformly arranged bolts 8 pass through the upper pressing plate 7 and are threadedly connected to the upper part of the flange 5, the annular edge of the upper cover body 1 is pressed between the upper pressing plate 7 and the flange 5, the lower pressing plate 6 is arranged on the lower side of the annular edge of the lower cover body 2, another part of the circumferentially uniformly arranged bolts 8 pass through the lower pressing plate 6 and are threadedly connected to the lower part of the flange 5, the annular edge of the lower cover body 2 is pressed between the lower pressing plate 6 and the flange 5, and the relative positions of the lower pressing plate 6, the upper pressing plate 7 and the flange 5 are fixed;

[0047] The connection part between the upper cover body 1 and the flange 5, and the connection part between the flange 5 and the lower cover body 2 are processed with sealing grooves, and sealing O-rings are arranged in the sealing grooves;

[0048] The arc shell is hemispherical, the inner diameter of the arc shell of the upper cover body 1 is 200mm, the outer diameter of the arc shell of the lower cover body 2 is 90mm, and the main vacuum chamber (chamber) is designed as a double hemispherical structure, which can improve the uniformity of radial discharge. According to the aerodynamic shape of the hypersonic aircraft, the design of the hemispherical chamber can greatly simulate the plasma environment of the plasma sheath head stagnation area; the spiral coil 4 is a spiral four-turn coil tower structure, and the pitch is selected to be 13.75cm, and the incense coil 3 is a coil four-turn coil plane structure, and the pitch is selected to be 13.75cm; the design of the spiral four-turn coil structure can greatly regulate the uniformity of chamber discharge and realize radially uniform plasma density distribution; the pitch is selected to be 13.75 spacing, which can greatly improve the uniformity of plasma discharge and realize high-density plasma; the design of the coil four-turn coil structure can generate plasma at the bottom, and can realize the modulation of the spatial distribution of plasma density in the entire chamber;

[0049] It also includes a vacuum system, a matcher, a radio frequency source and a diagnostic system. The vacuum system is connected to the interface tube 51, the two poles of the coil, the matcher and the radio frequency source are electrically connected in sequence, and the diagnostic system is connected to the connection port 11;

[0050] The vacuum system includes an air charging system (gas flow meter), an air extraction system (Roots pump and molecular pump), a vacuum measuring system (vacuum gauge) and an air release valve. The inert gas storage tank is connected to the first interface pipe 51 through the gas flow meter for air replenishment, the Roots pump, the molecular pump and the second interface pipe 51 are connected in sequence for air extraction, the vacuum gauge is connected to the third interface pipe 51 for detecting the vacuum degree, and the air release valve is connected to the fourth interface pipe 51 for air release.

[0051] The inflation system uses a seven-star flowmeter to control the gas flow, providing a stable discharge vacuum environment, with adjustable air intake, and is compatible with a variety of gases such as argon, helium, nitrogen, and air. It has the characteristics of simple structure, high precision, and strong wear resistance, so it has been widely used; the equation gas flowmeter mainly uses the principle of thermal diffusion. The physical conditions of the thermal diffusion principle are mainly composed of two temperature-sensitive thermal resistors, one of which is used as a speed sensor and the other as a temperature sensor to realize the automatic compensation function of gas temperature changes; when the physical conditions are met, the thermal gas flowmeter will be in normal working condition. Once the gas flows, the temperature sensor will increase or decrease its temperature to keep the gas flow constant. Therefore, the gas flow rate can be judged by measuring the current in the circuit;

[0052] The vacuum pump part of the exhaust system adopts a multi-stage Roots pump for exhaust, and the ultimate vacuum pressure is less than 0.1Pa; the vacuum pump group is connected to the chamber with a stainless steel pipe, and the Roots pump is equipped with an independent gate valve, pre-extraction pipes and valves; the pipe diameter does not affect the efficiency of the vacuum pump; the pipe layout does not affect the use of the vacuum chamber window and the movement of other equipment;

[0053] A vacuum gauge is arranged in the vacuum chamber to monitor the background pressure before plasma discharge and the working pressure during discharge. The PG800 resistance vacuum gauge can cover 10 -2 -10 5 Measuring range of Pa;

[0054] The diagnostic system includes a probe, which is connected to the connection port 11 for diagnosing plasma density; the interface 11 is made of quartz glass with an outer diameter of 30 mm, and the mobile probe platform interface is a KF40 stainless steel adapter; an axial double rubber ring sealing structure is used to connect the interface 11 to the probe platform; a single probe mobile platform is designed with a travel distance of 25 cm, which can diagnose the spatial distribution of plasma in real time and meet the spatial resolution diagnosis of the entire vacuum chamber;

[0055] The plasma source system uses a 0-2000W Jizhao source RF power supply and a matching automatic matcher connected to a four-turn spiral coil and a coil to generate an inductively coupled plasma in a vacuum chamber; the RF power supply can set the power by adjusting the configuration values ​​of the capacitor and inductor to control the incident power and reflected power of the RF source to achieve the adjustment of the set power; the RF source is connected to the automatic matcher through a shielded coaxial cable and a data transmission line. When the Jizhao source power is high, cooling water is required for the RF source; a copper bus is used to connect the coil to the matcher, and the matcher and the RF source need to be grounded when in use; the RF source operation panel is used to adjust the capacitance and inductance of the RF matcher to adjust the power fed into the coil. The double coil connection method can improve the uniformity of plasma density distribution and change The spatial distribution of the plasma density in the chamber is shown; the numerical simulation results show that when the four-turn spiral coil is used alone, the plasma it produces is mainly concentrated in the top area of ​​the chamber; when the four-turn incense coil is used alone, the plasma it produces is mainly concentrated in the bottom area of ​​the chamber; when the four-turn spiral coil and the incense coil are used in series, the plasma it produces is mainly concentrated in the middle top area of ​​the chamber, and the plasma density is improved compared with the single coil operation; when the four-turn spiral coil and the incense coil are used in parallel, the spatial distribution of the plasma density changes with the increase of power; therefore, the dual-coil coordinated control method can be used, which can not only improve the plasma density under the same working conditions, but also realize the regulation of the spatial distribution of the plasma density;

[0056] The present invention mainly provides a plasma environment matching the antenna radiation characteristic modulation, and needs to realize the directional control of the density distribution of the plasma space; through the double coil control method of the four-turn spiral coil and the incense coil, it can not only realize the plasma density can be (10 10 ~10 12 cm-3 ) range distribution is adjustable, and directional control of the spatial distribution of plasma density can also be achieved.

[0057] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hemispherical inductively coupled plasma source with adjustable density distribution, characterized in that: The invention comprises an upper cover body (1), a lower cover body (2), a flange (5) and a coil. The upper cover body (1), the lower cover body (2) and the flange (5) are coaxially arranged in sequence from top to bottom, and a chamber is formed between the upper cover body (1) and the lower cover body (2). A mouthpiece (51) is arranged on the side of the flange (5), the chamber is connected to the mouthpiece (51), and a coil is arranged on the outside of the chamber.

2. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 1, characterized in that: The material of the upper cover body (1) and the lower cover body (2) is quartz. The upper parts of the upper cover body (1) and the lower cover body (2) both have hemispherical shells, and the lower edges of the hemispherical shells have an annular edge.

3. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 2, characterized in that: A connection port (11) is arranged in the middle of the upper cover body (1), or a plurality of connection ports (11) are arranged equidistantly in the circumferential direction on the upper part of the upper cover body (1), and the connection port (11) is communicated with the chamber.

4. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 3, characterized in that: The flange (5) is made of stainless steel, and four interface pipes (51) are evenly arranged on the side of the flange (5).

5. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 4, characterized in that: The coil comprises a spiral coil (3) and / or an incense coil (4), wherein the spiral coil (3) is arranged above the upper cover body (1), and the incense coil (4) is arranged below the lower cover body (2).

6. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 5, characterized in that: The bottom of the annular edge of the lower cover body (2) is processed with a coil installation groove (21), and the incense coil (4) is installed in the coil installation groove (21).

7. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 6, characterized in that: The invention also comprises a lower pressure plate (6), an upper pressure plate (7) and a bolt (8), wherein the lower pressure plate (6), the upper pressure plate (7) and the bolt (8) are made of polytetrafluoroethylene. The lower pressure plate (6) and the upper pressure plate (7) are annular. The upper pressure plate (7) is arranged on the upper side of the annular edge of the upper cover body (1), and the bolt (8) passes through the upper pressure plate (7) and is connected to the upper thread of the flange (5), so that the annular edge of the upper cover body (1) is pressed between the upper pressure plate (7) and the flange (5). The lower pressure plate (6) is arranged on the lower side of the annular edge of the lower cover body (2), and the bolt (8) passes through the lower pressure plate (6) and is connected to the lower thread of the flange (5), so that the annular edge of the lower cover body (2) is pressed between the lower pressure plate (6) and the flange (5).

8. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 7, characterized in that: The connection part between the upper cover body (1) and the flange (5), and the connection part between the flange (5) and the lower cover body (2) are processed with sealing grooves, and sealing O-rings are arranged in the sealing grooves.

9. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 8, characterized in that: The arc-shaped shell is hemispherical, the inner diameter of the arc-shaped shell of the upper cover body (1) is 200 mm, and the outer diameter of the arc-shaped shell of the lower cover body (2) is 90 mm; the incense coil (4) is a four-turn incense coil structure, and the pitch is selected to be 13.75 cm, and the spiral coil (3) is a four-turn spiral coil structure, and the pitch is selected to be 13.75 cm.

10. The hemispherical inductively coupled plasma source with adjustable density distribution according to claim 9, characterized in that: It also includes a vacuum system, a matcher, a radio frequency source and a diagnostic system. The vacuum system is connected to the interface tube (51), the two poles of the coil, the matcher and the radio frequency source are electrically connected in sequence, and the diagnostic system is connected to the connection port (11).

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