A hemispherical inductively coupled plasma source with adjustable density distribution

Abstract

The present invention relates to a hemispherical inductively coupled plasma source with adjustable density distribution, belonging to the technical field of plasma generation devices. The device comprises an upper housing, a lower housing, a flange, and a coil. The upper, lower, and flanges are coaxially arranged from top to bottom, forming a chamber between the upper and lower housings. An interface pipe is provided on the side of the flange, connecting the chamber to the interface pipe, and a coil is disposed outside the chamber. The present invention is primarily used in the field of antenna radiation performance control, effectively achieving control of antenna radiation characteristics.

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 manipulate electromagnetic waves has attracted increasing attention. Antennas, the carriers of transmitted and received signals in wireless communication systems, play a crucial role in determining the quality of communication signals. Therefore, optimizing antenna performance is of great research value. Antenna gain is the most critical parameter, largely determining the performance of an antenna. The higher the antenna gain, the greater its effective coverage range and the longer the transmission distance.

[0003] With the development of aerospace, 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 mutually exclusive. Traditional approaches have adopted a compromise solution: increasing the antenna's volume to achieve a relatively high gain within an acceptable range. This limits the size that can be reduced while maintaining high gain, hindering the design's miniaturization and lightweighting. Therefore, how to ensure high antenna gain while also miniaturizing it is a worthy challenge. In recent years, researchers have proposed subwavelength plasma-enhanced microwave electromagnetic radiation technology, which provides a new approach to resolving this contradiction between miniaturization and high gain. This technology introduces plasma, making passive antenna gain enhancement a relatively independent, modular approach that can ignore other antenna parameters. Subwavelength plasma enhancement effectively decouples these two conflicting requirements: 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, volume 26, issue 3, and article number 033509. The technical solution in this article states that the spatial distribution of plasma density cannot be directionally controlled - part of the uniformity requires the realization of a non-uniform distribution with a 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, which was published in the journal "Japanese Journal of Applied The article is published in the journal Physics, volume 55, issue 6, and article number 065201. The technical solution described 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 lacks a control strategy for how to control 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 26, article number 033509. The technical solution is to use a bottom plane incense coil excitation method to discharge in a hemispherical structure chamber. The bottom plane incense coil excitation method can only adjust the plasma density, but cannot change the spatial distribution of plasma density in the chamber.

[0005] In terms of patents, the publication number is CN106025546B, and the name of the invention is "Device for enhancing the electromagnetic radiation of miniaturized omnidirectional antennas using plasma modulation." Its technical solution uses a cylindrical inductively coupled plasma source to generate non-uniform plasma, which cannot 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 electrically small antenna to achieve the enhancement of the radiation capacity of the electrically small antenna by non-uniform plasma. The non-uniformity proposed in its technical solution is a monotonous non-uniform plasma, which cannot 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 generating device and its use method." Its technical solution uses a dual-frequency driven discharge method to regulate the density of plasma discharge, but lacks the regulation of the spatial distribution of plasma density. Publication number CN104981086B, the invention is titled "Enhanced RF Inductively Coupled Plasma Discharge Device." Its technical solution utilizes an external helical coil to generate plasma from a cylindrical inductively coupled plasma source, capable of producing high-density, large-area, uniform, and stable plasma. However, the cylindrical discharge chamber structure with the external helical coil has end caps on both sides, preventing omnidirectional gain for the small antenna. Furthermore, the end caps on both sides also affect the gain of the measurement antenna.

[0006] Exploring the antenna radiation characteristics of subwavelength plasmas and achieving effective decoupling of antenna miniaturization and high gain under non-uniform plasma sheathing has important applications in areas such as intelligent base stations for information networks and intelligent control of aircraft electromagnetic environments. Currently, most researchers use low-temperature inductively coupled plasmas (ICPs) to provide a suitable plasma environment for modulating antenna radiation enhancement characteristics. RF inductively coupled plasmas are primarily of two types, depending on the coil winding method: a planar coil-type ICP source, in which a flat coil similar to a mosquito coil is placed on a quartz window at the top of the discharge chamber; and a cylindrical spiral coil ICP source, in which a spiral-shaped coil is wound around the sidewall of a cylindrical quartz discharge chamber. For a plasma environment to modulate antenna radiation characteristics, it is necessary not only to generate a relatively stable plasma but also to control the spatial distribution of the plasma and sense key parameters. Therefore, planar coil-type and cylindrical ICP sources are insufficient for antenna radiation modulation research. There is an urgent need to design an ICP source that can generate a stable plasma, control the spatial distribution of the 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] To explore the antenna radiation characteristics of subwavelength plasmas, address the key issue of traditional metal antennas being unable to achieve high gain and miniaturization, and develop and improve the laws, mechanisms, and theoretical systems for the influence of plasma parameters on radiation enhancement under non-uniform plasma sheathing, it is necessary to provide a hemispherical inductively coupled plasma source with adjustable density distribution to achieve directional control of the density distribution in the plasma region. The present invention provides a plasma environment that matches the modulation of antenna radiation characteristics. It is suitable for plasma generators where electromagnetic waves interact with plasmas and can achieve spatial control of plasma density distribution (directional non-uniformity and symmetrical uniformity) for antennas under different complex spatial conditions. This addresses the multiple limitations of existing plasma generators, such as the inability to adjust density distribution, electron density, and background pressure. A brief overview of the present invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive overview of the invention. It is not intended to identify key or important aspects of the invention, nor is it intended to limit the scope of the invention.

[0009] The technical solution of the present invention:

[0010] The present invention adopts a technical solution to solve the above-mentioned problem: a hemispherical inductively coupled plasma source with adjustable density distribution, comprising an upper cover, a lower cover, a flange and a coil, wherein the upper cover, the lower cover and the flange are coaxially arranged in sequence from top to bottom, forming a chamber between the upper cover and the lower cover, an interface pipe is provided on the side of the flange, the chamber is connected to the interface pipe, and a coil is provided 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 shell has an annular 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 distance from the spiral coil at different positions to the outer wall of the cover body is 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 mounting groove is processed on the bottom of the annular edge of the lower cover body, and an incense coil is installed in the coil mounting 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 circumferentially uniformly arranged bolts (a sealing groove is provided, and 12 PTFE bolts are used to evenly seal the chamber - an O-ring is used for sealing between the flange and the cover body, and a PTFE pad is used for protection between the cover body and the pressure cover) passes through the upper pressure plate and is connected to the upper thread of the flange, pressing the annular edge of the upper cover body 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 circumferentially uniformly arranged bolts pass through the lower pressure plate and is connected to the lower thread of the flange, pressing the annular edge of the lower cover body 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 provided 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, wherein 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 discharge uniformity. In addition, the double-hemispherical structure can greatly improve the uniformity of the discharge chamber plasma through a simple and ingenious structural design. The double-hemispherical structure can not only improve the uniformity of the discharge chamber plasma, but also regulate the thickness of the plasma sheath, which can be used to 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 shortcomings of poor radial uniformity and inability to control the spatial distribution of plasma; the excitation method of the spiral coil and the incense coil can not only modulate the spatial distribution of plasma 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, thickness and density distribution are adjustable.

[0023] 3. Compared with the traditional inductively coupled plasma discharge structure, the present invention adopts a hemispherical structure with a branch pipe in combination 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 realize 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 stereoscopic diagram of a hemispherical inductively coupled plasma source with adjustable density distribution;

[0025] Figure 2 This 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 double branches and adjustable density distribution;

[0029] Figure 6 The 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 diagnostic diagram 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] Figure 9 This is a simulation diagram of the incense coil being excited separately;

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

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

[0035] Figure 12 This is a graph of experimental data on 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 mounting slot, 51-interface pipe. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0038] Specific implementation method 1: Combination Figure 1-12 This embodiment describes a ground-based simulation device for a near-space plasma sheath head environment, comprising an upper cover 1, a lower cover 2, a flange 5, and a coil. The upper cover 1, the lower cover 2, and the flange 5 are coaxially arranged from top to bottom, forming a chamber between the upper cover 1 and the lower cover 2. A port 51 is provided on the side of the flange 5, the chamber is in communication with the port 51, and a coil is provided on the outside of the chamber.

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

[0040] A connection port 11 is provided at the top of the upper cover 1, or a plurality of connection ports 11 are provided circumferentially and equidistantly on the upper portion of the upper cover 1, and the connection port 11 is connected to the chamber. The use of a spherical cover chamber can improve the uniformity of the plasma space in the radial direction, thereby achieving a more uniform plasma. The connection port 11 of the upper cover can be used to diagnose the plasma spatial distribution and plasma parameters in real time.

[0041] The flange 5 is made of 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 an incense coil 4. The spiral coil 3 is arranged above the upper cover 1. The spiral coil 3 and the upper cover 1 can be fixed by insulating tape. The spiral coil 3 is arranged along the outer wall of the upper cover 1 so that the vertical distance from different positions of the spiral coil 3 to the outer wall of the upper cover 1 is equal. The incense coil 4 is arranged below the lower cover 2 and is coaxial with the lower cover 2.

[0043] The present invention provides a density-adjustable hemispherical inductively coupled plasma generator for antenna radiation characteristic modulation. The main generation method is an inductively coupled plasma source (ICP). The radio frequency ICP source can generate plasma without the action 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 includes: a double coil (inductively coupled plasma source), a radio frequency power supply, and a matcher. A double-coil excitation inductively coupled discharge technical solution is designed. The upper coil is a four-turn spiral coil structure, and the lower coil is a four-turn incense coil structure. By changing the coil connection method, the upper and lower double coil discharge powers can be independently controlled to adjust the spatial distribution of plasma density. When used alone, 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 when the coil is working alone; 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 to not only increase 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 radial plasma density distribution uniformity 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 it from the traditional incense coil excitation method, through simulation structure analysis, the pitch of the coil is selected to be in the range of 13.75cm, which can greatly optimize the uniformity of the plasma density spatial distribution and generate a more uniform plasma source in the hemispherical discharge chamber. Compared with the excitation of the spiral coil and the incense coil, the dual-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 in the range of 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 incense coil 4 is installed in the coil installation groove 21; the present invention provides a plasma environment that matches the modulation of the antenna radiation characteristics, and it is necessary to realize the directional control of the density distribution of the plasma space; compared with the traditional columnar and incense coil type ICP structures, the device adopts a hemispherical discharge chamber structure and uses a four-turn spiral coil to coordinate the control with the incense coil, which can not only realize the plasma density between 10 10 ~10 12 cm -3 The magnitude is adjustable within a certain range, and the spatial distribution of plasma density can also be regulated. The four-turn incense coil used in this device operates in an air environment without plasma sheathing. It 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 this device also operates in an air environment and generates plasma through inductive coupling of an RF power supply. Compared to the working environment of an antenna, one antenna operates in an argon plasma environment. The antenna of the device of the present invention operates in an air environment and discharges through the inductive coupling principle of an RF power supply.

[0046] It also includes a lower pressing plate 6, an upper pressing plate 7 and a bolt 8. The material of the lower pressing plate 6, the upper pressing plate 7 and the bolt 8 is 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, and 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, pressing the annular edge of the upper cover body 1 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, and 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, pressing the annular edge of the lower cover body 2 between the lower pressing plate 6 and the flange 5. The relative positions of the lower pressing plate 6, the upper pressing plate 7 and the flange 5 are fixed;

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

[0048] The arc-shaped shell is hemispherical, the inner diameter of the arc-shaped shell of the upper cover 1 is 200 mm, and the outer diameter of the arc-shaped shell of the lower cover 2 is 90 mm. 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 simulate the plasma environment in the stagnation area of ​​the plasma sheath head to a great extent; the spiral coil 3 is a spiral four-turn coil tower structure with a pitch of 13.75 cm, and the incense coil 4 is a coil four-turn coil plane structure with a pitch of 13.75 cm; the design of the spiral four-turn coil structure can greatly regulate the uniformity of chamber discharge and achieve uniform plasma density distribution in the radial direction; the pitch is selected as 13.75 pitch, which can greatly improve the uniformity of plasma discharge and achieve high-density plasma; the design of the incense four-turn coil structure can generate plasma at the bottom, which can realize the modulation of the spatial distribution of plasma density in the entire chamber;

[0049] It also includes a vacuum system, a matching device, 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 matching device 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 inflation system (gas flow meter), an exhaust system (Roots pump and molecular pump), a vacuum measurement system (vacuum gauge), and a purge valve. The inert gas storage tank is connected to the first interface pipe 51 via the gas flow meter for gas replenishment. The Roots pump, molecular pump, and second interface pipe 51 are connected in sequence for exhaust. The vacuum gauge is connected to the third interface pipe 51 for vacuum detection. The purge valve is connected to the fourth interface pipe 51 for deflation.

[0051] The inflation system uses a seven-star flowmeter to control the gas flow, providing a stable discharge vacuum environment. The air intake volume is adjustable 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, and has therefore 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-sensing thermal resistors, one of which serves as a speed sensor and the other as a temperature sensor to achieve automatic compensation for 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 uses a multi-stage Roots pump for exhaust, with a maximum vacuum pressure of less than 0.1Pa. The vacuum pump group is connected to the chamber using stainless steel pipes. 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 placed 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 connected to a connector 11 for diagnosing plasma density. The connector 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 seal is used to connect the connector 11 to the probe platform. A single-probe mobile platform with a travel distance of 25 cm is designed to diagnose the spatial distribution of plasma in real time, meeting the requirements of spatially resolved 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 an incense coil to generate 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 dual-coil connection method can improve the uniformity of the plasma density distribution and change The spatial distribution of the plasma density in the chamber is studied; the numerical simulation results show that when the four-turn spiral coil is used alone, 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 when the coil is used alone; 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 that matches 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, not only the plasma density can be adjusted between (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 permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0058] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A hemispherical inductively coupled plasma source with adjustable density distribution, characterized in that: The device comprises an upper cover (1), a lower cover (2), a flange (5) and a coil, wherein the upper cover (1), the lower cover (2) and the flange (5) are coaxially arranged in sequence from top to bottom, and a chamber is formed between the upper cover (1) and the lower cover (2). A mouthpiece (51) is provided on the side of the flange (5), the chamber is in communication with the mouthpiece (51), and a coil is provided on the outside of the chamber. The upper portion of the upper cover body (1) and the lower cover body (2) both have a hemispherical shell, and the lower edge of the hemispherical shell has an annular edge.

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.

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 circumferentially and equidistantly 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 (1), and the incense coil (4) is arranged below the lower cover (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 (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 includes 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), pressing the annular edge of the upper cover body (1) 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), pressing the annular edge of the lower cover body (2) 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 portion between the upper cover body (1) and the flange (5), and the connection portion 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 (1) is 200 mm, and the outer diameter of the arc-shaped shell of the lower cover (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; 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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