A radio frequency coupling plasma source applied to a positive pressure environment

Abstract

This invention relates to the field of plasma source technology, and more particularly to a radio frequency coupled plasma source for use under positive pressure environments. The technical solution includes an ion source inlet interface connected to a gas source; an ion source chamber connected to the ion source inlet interface, with a connecting component fixed between the ion source inlet interface and the ion source chamber; an ion sputtering baffle fixedly installed at the bottom of the ion source chamber; a radio frequency power supply disposed on one side of the ion source chamber, with a coil installed between the ion source chamber and the radio frequency power supply; and a support mechanism for supporting the ion source chamber. This invention can meet the requirements for using an ion source under positive pressure environments, avoiding the influence of external pressure gas environments on the source. It satisfies both the operating conditions of the ion source under external positive pressure environments and the need for frequent replacement of the plasma chamber in radio frequency coupled plasma sources. It is low-cost and easy to maintain and replace.

Description

Technical Field

[0001] This invention relates to the field of plasma source technology, and in particular to a radio frequency coupled plasma source applicable to a positive pressure environment. Background Technology

[0002] Using a small accelerator neutron source based on neutron activation method 98 Mo(n,γ) 99 Mo reaction preparation 99 Mo's scheme involves a 1.5MV ultra-high voltage power supply. Since the atmospheric insulation level cannot meet the insulation requirements of the ultra-high voltage power supply, the power supply itself and the corresponding MV-level ion source accelerator system should be placed inside a sealed cavity filled with SF6 gas. The SF6 pressure inside the cavity is determined by the voltage required by the MV-level ion source accelerator system; the maximum voltage is 1.5MV, and the SF6 pressure needs to reach 0.6MPa. Therefore, the structure of the radio frequency coupled ion source needs to be optimized to meet the requirements under a positive pressure environment. Radio frequency coupled plasma sources typically use ceramic or glass tubes as excitation chambers, with both ends sealed with metal covers and rubber rings to create a vacuum. This structure can function normally in an atmospheric environment, and the system leakage rate meets requirements. However, when the external environment is changed to pressurized gas, the previously acceptable leakage rate gradually increases, as external gas seeps into the ion source cavity through the sealing rubber rings, resulting in impurities and contaminating the beam. To address the ion source leakage problem under external pressure environments, this application proposes a radio frequency coupled plasma source for use in a positive pressure environment. Summary of the Invention

[0003] The purpose of this invention is to address the problem of ion source leakage under external pressure in the prior art, and to propose a radio frequency coupled plasma source applicable to positive pressure environments.

[0004] The technical solution of the present invention: a radio frequency coupled plasma source applied under positive pressure environment, including a gas source and an ion source inlet interface connected to the gas source;

[0005] An ion source chamber is connected to the ion source inlet interface, and a connecting component is fixed between the ion source inlet interface and the ion source chamber. An ion sputtering baffle is fixedly installed inside the bottom of the ion source chamber.

[0006] A radio frequency power supply is disposed on one side of the ion source chamber, and a coil is installed between the ion source chamber and the radio frequency power supply;

[0007] A support mechanism is provided for supporting the ion source chamber, and a connecting component 2 is installed between the support mechanism and the bottom of the ion source chamber.

[0008] Optionally, the connecting assembly includes an ion source upper sealing cover plate one that presses against the top of the ion source chamber, the bottom of the ion source air inlet port penetrating through the ion source upper sealing cover plate one, an ion source upper sealing cover two fixedly sleeved on the top of the ion source chamber below the ion source upper sealing cover plate one, the ion source upper sealing cover two and the ion source upper sealing cover plate one being connected by a sealing screw one, and an O-ring seal between the ion source upper sealing cover plate one and the ion source upper sealing cover two being sleeved on the top of the ion source chamber.

[0009] Optionally, a rectangular groove is provided at the bottom of the sealing cover plate of the ion source, the top of the ion source chamber is fixedly connected to the inner wall of the rectangular groove, and a rectangular rubber ring located at the top of the ion source chamber is installed in the rectangular groove.

[0010] Optionally, the connecting component two includes an ion source lower sealing plate one that presses against the support mechanism, and the ion source lower sealing plate two is fixedly sleeved at the bottom of the ion source chamber. The ion source lower sealing plate one and the ion source lower sealing plate two are connected by a sealing screw two.

[0011] Optionally, an insulating screw is fixedly installed on the top of the lower sealing plate of the ion source, and the top of the insulating screw slides through the upper sealing cover of the ion source and is threaded with a sealing nut that presses against the upper sealing cover of the ion source.

[0012] Optionally, the support mechanism is installed on the PG electrode base at the bottom of the lower sealing plate of the ion source. An insulating support is fixedly installed on the bottom of the PG electrode base, and an EG electrode base, an insulating support 2, and a GG electrode base are fixedly installed on the bottom of the insulating support 1 in sequence.

[0013] Optionally, a sealing bolt is threaded onto the lower sealing plate of the ion source. The sealing bolt is threaded through the PG electrode base and threadedly connected to a sealing nut, which abuts against the bottom of the PG electrode base.

[0014] Optionally, a metal sealing ring is installed between the lower sealing plate of the ion source and the PG electrode base.

[0015] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0016] This invention provides a radio frequency coupled plasma source applicable to a positive pressure environment, which can meet the requirements of ion source use in a positive pressure environment and avoid the influence of external pressure gas environment on the source.

[0017] This invention employs a multi-ring seal for plasma chamber sealing, which satisfies both the operating conditions of the ion source under external positive pressure and the requirement for frequent replacement of the plasma chamber in radio frequency coupled plasma sources. Compared with welded seals, the plasma chamber sealed with multiple rings can be reused, reducing costs.

[0018] The radio frequency coupled plasma source designed in this invention has a high degree of modularity, and almost all components can be replaced individually, which is convenient for maintenance. The reserved electrode base can meet the requirements of replacing electrodes with different structures, and the electrodes can be replaced in time when the electrode structure cannot meet the requirements. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a radio frequency coupled plasma source applied under positive pressure environment;

[0020] Figure 2 This is a schematic diagram of the connection structure between the sealing cover plate on the ion source and the ion source chamber.

[0021] Reference numerals in the attached diagram: 1. Ion source gas inlet; 2. Insulating screw; 3. Sealing nut one; 4. Rectangular rubber ring; 5. Ion source upper sealing cover one; 6. O-ring seal; 7. Sealing screw one; 8. Ion source upper sealing cover two; 9. Ion source chamber; 10. Gas source; 11. Radio frequency power supply; 12. Coil; 13. Ion sputtering baffle; 14. Ion source lower sealing plate two; 15. Sealing bolt; 16. Ion source lower sealing plate one; 17. Metal sealing ring; 18. PG electrode base; 19. Sealing nut two; 20. Insulating support one; 21. EG electrode base; 22. Insulating support two; 23. GG electrode base. Detailed Implementation

[0022] The technical solutions of this disclosure will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments.

[0023] The components of the embodiments of this disclosure, which are typically described and shown in the accompanying drawings, can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of embodiments of this disclosure provided in the drawings is not intended to limit the scope of the claimed disclosure, but merely to illustrate selected embodiments of the disclosure.

[0024] Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this disclosure.

[0025] Example

[0026] like Figure 1As shown, this invention proposes a radio frequency coupled plasma source for use under positive pressure conditions, comprising a gas source 10 and an ion source inlet interface 1 connected to the gas source 10. The ion source inlet interface 1 delivers gas flow, and the gas source 10 serves as the working gas for the radio frequency coupled plasma source. The gas type is selected as hydrogen or deuterium based on the target ions extracted according to the system design. The designed radio frequency coupled plasma source can directly replace the gas source without changing other equipment to generate other types of plasma, thereby extracting the desired ions.

[0027] An ion source chamber 9 is connected to the bottom of the ion source inlet interface 1. A connecting component 1 is fixed between the ion source inlet interface 1 and the ion source chamber 9. The connecting component 1 includes an ion source upper sealing cover plate 5 that presses against the top of the ion source chamber 9. The bottom of the ion source inlet interface 1 passes through the ion source upper sealing cover plate 5. The ion source inlet interface 1 is made of a standard 1 / 4-inch steel pipe welded to the ion source upper sealing cover plate 1. It uses a standard 1 / 4-inch compression fitting interface to connect and seal with other pipelines. An ion source upper sealing cover 2 8 is fixedly fitted on the top of the ion source chamber 9, located below the ion source upper sealing cover plate 5. The ion source upper sealing cover 2 8 is connected to the ion source upper sealing cover plate 1 5 by a sealing screw 7. An O-ring 6 is fitted on the top of the ion source chamber 9, located between the ion source upper sealing cover plate 1 5 and the ion source upper sealing cover 2 8.

[0028] The ion source upper sealing cover 5 has a rectangular groove at its bottom. The top of the ion source chamber 9 is fixedly connected to the inner wall of the rectangular groove. A rectangular rubber ring 4 is installed inside the rectangular groove at the top of the ion source chamber 9. The ion source upper sealing cover 5 is a metal flange made of common 304 stainless steel. Its main function is to seal the upper end of the ion source chamber 9 in conjunction with the rectangular rubber ring 4. It is the main seal at the upper end of the ion source chamber 9. The rectangular rubber ring 4 is a ring-shaped rectangular gasket made of fluororubber, molded or machined. The rectangular rubber ring 4 is made of fluororubber, which has the advantages of high temperature resistance, corrosion resistance, and good stability. An ion sputtering baffle 13 is fixedly installed inside the bottom of the ion source chamber 9. The main function of the ion sputtering baffle 13 is to reduce the contamination of the ion source chamber 9 by sputtered ions generated by the collision between the plasma and the extraction electrode. The material of the ion sputtering baffle 13 can be quartz or other materials with low secondary electron emission coefficient.

[0029] In this embodiment, an RF power supply 11 is provided on one side of the ion source chamber 9, and a coil 12 is installed between the ion source chamber 9 and the RF power supply 11. The RF power supply 11 is a commercially available RF power supply and automatic matching device of a common frequency. The RF power supply is selected as 13.56MHz or 1MHz according to the design requirements of the RF coupled plasma source, and the power is selected as 300-1000W. The RF coupled plasma source system design has a well-compatible interface reserved for the RF power supply 11, which can be replaced with RF power supplies of different power and frequency at any time according to system needs to meet different system requirements. The ion source chamber 9 is the main excitation chamber of the RF coupled plasma. The ion source chamber 9 is made of quartz or ceramic and is usually cylindrical in shape. A coil is wound around the outside of the ion source chamber 9. The RF power supply couples power into the excitation ion source chamber 9 through the coil 12, ionizing the gas into plasma.

[0030] The coil 12 is a multi-turn copper tube wound around the ion source chamber 9. The two ends of the copper tube are connected to radio frequency power matching devices to couple radio frequency power into the ion source chamber 9, ionizing the gas into plasma. The outer diameter of the copper tube is selected from 3 to 8 mm according to the system requirements, and the number of turns is 5 to 10.

[0031] A support mechanism is used to support the ion source chamber 9. A connecting component two is installed between the support mechanism and the bottom of the ion source chamber 9. The connecting component two includes an ion source lower sealing plate 16 that presses against the support mechanism. An ion source lower sealing plate 14 is fixedly sleeved on the bottom of the ion source chamber 9. The ion source lower sealing plate 16 and the ion source lower sealing plate 14 are connected by sealing screws. The ion source lower sealing plate 14 is a metal flange made of 304 stainless steel. It is smaller than the ion source upper sealing cover plate 5. Its main function is to work with the O-ring 6 to provide a secondary seal on the radial surface of the ion source chamber 9, reducing the infiltration of external gas into the ion source chamber 9.

[0032] It is worth noting that an insulating screw 2 is fixedly installed on the top of the ion source lower sealing plate 16. The top of the insulating screw 2 slides through the ion source upper sealing cover plate 5 and is threaded with a sealing nut 3 that presses against the ion source upper sealing cover plate 5. The insulating screw 2 and the sealing nut 3 ensure the stability of the connection between the ion source upper sealing cover plate 5, the ion source chamber 9, and the ion source lower sealing plate 16. The ion source lower sealing plate 16 is a metal flange, which is mainly used to seal the lower end of the ion source chamber 9 with the rectangular rubber ring 4, serving as the main seal for the lower end of the ion source chamber 9. At the same time, it provides a support platform for the ion sputtering baffle 13.

[0033] Furthermore, the insulating screw 2 is primarily responsible for tightening the upper sealing cover plate 5 and the lower sealing plate 16 of the ion source. The insulating screw 2 presses the upper sealing cover plate 5 against the rectangular rubber ring 4, thereby sealing the ion source chamber 9. The lower sealing plate 16 of the ion source has threaded holes for mounting the insulating screw 2. The insulating screw 2 is made of PEEK or polyoxymethylene, materials with low conductivity, and also needs sufficient mechanical strength to prevent the sealing nut from breaking off, causing vacuum rupture, and damaging other equipment.

[0034] The support mechanism is installed on the PG electrode base 18 at the bottom of the sealing plate 16 of the ion source. An insulating support 20 is fixedly installed at the bottom of the PG electrode base 18. An EG electrode base 21, an insulating support 22, and a GG electrode base 23 are fixedly installed at the bottom of the insulating support 20 in sequence.

[0035] A sealing bolt 15 is threaded onto the lower sealing plate 16 of the ion source. The sealing bolt 15 is threaded through the PG electrode base 18 and threadedly connected to a sealing nut 19. The sealing nut 19 abuts against the bottom of the PG electrode base 18, thereby connecting the lower sealing plate 16 of the ion source and the PG electrode base 18.

[0036] A metal sealing ring 17 is installed between the ion source lower sealing plate 16 and the PG electrode base 18. The metal sealing ring 17 serves as the vacuum sealing medium between the ion source lower sealing plate 16 and the PG electrode base 18. The material is typically a low-hardness metal such as oxygen-free copper, silver wire, or indium wire, and is made into different shapes depending on the sealing structure. Sealing bolts 15 and sealing nuts 19 are used to tighten the ion source lower sealing plate 16 and the PG electrode base 18, causing the metal sealing ring 17 to deform and tightly fit the interface between the ion source lower sealing plate 16 and the PG electrode base 18, thereby achieving a vacuum pressure seal.

[0037] In this embodiment, the PG electrode base 18 provides a fixed and leveling mounting surface for the PG electrode, and the material is selected as 304 stainless steel or Kovar alloy. One side of the PG electrode base 18 has a pre-reserved vacuum sealing interface with the lower sealing plate 16 of the ion source, which adopts a metal sealing form; the other side is bonded or welded to the insulating support 20. Both the upper and lower sealing surfaces of the PG electrode base 18 are unaffected by external environmental pressure, and the leakage rate always meets the experimental requirements.

[0038] The insulating support 20 serves as the insulating support between the PG electrode base 18 and the EG electrode base 21, sealingly connecting them. Materials with high dielectric constants, such as PEEK, epoxy, and ceramic, are selected. The bonding or welding method is chosen based on the materials of the insulating support 20 and the upper and lower electrode bases to ensure that the leakage rate at the sealing surface meets the requirements.

[0039] In this embodiment, the EG electrode base 21 is a metal flange, which provides a fixed and leveling mounting surface for the EG electrode. The material is usually 304 stainless steel or a valve-compatible metal. The flange of the EG electrode base 21 is sealed to the insulating support 20 and the insulating support 22 on both sides, respectively. The sealing method is selected by bonding or welding depending on the material. The seal must be able to maintain the required leakage rate under certain pressure.

[0040] It should be noted that the insulating support 22 serves as the insulating support between the EG electrode base 21 and the GG electrode base 23, connecting them. Materials typically chosen are PEEK, epoxy, or ceramics with high dielectric constants. The insulating support 22 must possess a certain vacuum pressure sealing capability with the EG electrode base 21 and the GG electrode base 23; the sealing method, whether adhesive or welding, is selected based on the materials used. The seal must maintain a certain sealing capability even under external pressure, and the leakage rate at the seal must meet experimental requirements.

[0041] In this embodiment, the GG electrode base 23 is a metal flange, which provides a fixed and leveling mounting surface for the GG electrode. The material is typically 304 stainless steel or a valveable metal. One side of the GG electrode base 23 needs to be vacuum pressure sealed to the insulating support 22, usually through bonding or welding depending on the materials used. The other side has a metal vacuum sealing interface for the ion transmission channel. Screws and nuts are used to tighten the metal vacuum sealing flange between the GG electrode base and the ion transmission channel (the GG electrode base is the interface between the radio frequency coupled plasma source and the ion transmission pipe; the ion transmission pipe is a general-purpose device and not shown in the figure), causing the metal sealing ring to deform and tightly fit the upper and lower flange interfaces, thereby achieving a vacuum pressure seal.

[0042] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A radio frequency coupled plasma source for use in a positive pressure environment, characterized in that, include: The gas source (10) is connected to the ion source inlet (1). An ion source chamber (9) is connected to the ion source inlet (1). A connecting component is fixed between the ion source inlet (1) and the ion source chamber (9). An ion sputtering baffle (13) is fixedly installed inside the bottom of the ion source chamber (9). A radio frequency power supply (11) is disposed on one side of the ion source chamber (9), and a coil (12) is installed between the ion source chamber (9) and the radio frequency power supply (11). A support mechanism for supporting the ion source chamber (9) is provided, and a connecting component 2 is installed between the support mechanism and the bottom of the ion source chamber (9); The connecting assembly includes an ion source upper sealing cover plate 1 (5) that presses against the top of the ion source chamber (9), the bottom of the ion source air inlet (1) passing through the ion source upper sealing cover plate 1 (5), and an ion source upper sealing cover 2 (8) located below the ion source upper sealing cover plate 1 (5) fixedly sleeved on the top of the ion source chamber (9). The ion source upper sealing cover 2 (8) and the ion source upper sealing cover plate 1 (5) are connected by a sealing screw 1 (7). An O-ring seal (6) located between the ion source upper sealing cover plate 1 (5) and the ion source upper sealing cover 2 (8) is sleeved on the top of the ion source chamber (9). A rectangular groove is provided at the bottom of the sealing cover plate (5) of the ion source, and the top of the ion source chamber (9) is fixedly connected to the inner wall of the rectangular groove. A rectangular rubber ring (4) located at the top of the ion source chamber (9) is installed in the rectangular groove. An insulating screw (2) is fixedly installed on the top of the lower sealing plate (16) of the ion source. The top of the insulating screw (2) slides through the upper sealing cover plate (5) of the ion source and is threaded with a sealing nut (3) that presses against the upper sealing cover plate (5) of the ion source. A metal sealing ring (17) is installed between the lower sealing plate (16) of the ion source and the PG electrode base (18).

2. The radio frequency coupled plasma source for use in a positive pressure environment according to claim 1, characterized in that, The second connecting component includes an ion source lower sealing plate (16) that presses against the support mechanism. The bottom of the ion source chamber (9) is fixedly fitted with an ion source lower sealing plate (14). The ion source lower sealing plate (16) and the ion source lower sealing plate (14) are connected by a sealing screw.

3. The radio frequency coupled plasma source for use in a positive pressure environment according to claim 2, characterized in that, The support mechanism is installed on the PG electrode base (18) at the bottom of the ion source lower sealing plate (16). The bottom of the PG electrode base (18) is fixedly installed with an insulating support (20). The bottom of the insulating support (20) is fixedly installed with an EG electrode base (21), an insulating support (22), and a GG electrode base (23) connected in sequence.

4. The radio frequency coupled plasma source for use in a positive pressure environment according to claim 3, characterized in that, A sealing bolt (15) is threaded on the lower sealing plate (16) of the ion source. The sealing bolt (15) is threaded through the PG electrode base (18) and threadedly connected to a sealing nut (19). The sealing nut (19) abuts against the bottom of the PG electrode base (18).

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