Plasma processing equipment

Abstract

The present invention provides a plasma processing apparatus that can improve plasma generation efficiency while also being miniaturized. [Solution] The plasma generation unit 10 generates plasma and includes at least a dielectric layer 11 and a pair of electrode layers provided on the front and back surfaces of the dielectric layer 11; a power supply unit applies an AC voltage to the pair of electrode layers; and a gas flow unit 20, which is cylindrical in shape and flows gas into the space outside the plasma generation unit 10 in order to process the gas with plasma, wherein the plasma generation unit 10 is installed spirally in the axial direction inside the gas flow unit 20.

Description

Technical Field

[0001] The present invention relates to a plasma processing apparatus. Background Art

[0002] In recent years, for plasma processing technology, a technique called Dielectric Barrier Discharge has been developed, which makes it possible to generate low-temperature plasma under atmospheric pressure. As a result, the application scope of plasma processing has expanded, and its use is progressing in various applications. Purposes of plasma processing include sterilization, deodorization, surface modification, and decomposition of chemical substances. Further, the substance to be subjected to plasma processing may be any of solid, liquid, or gas.

[0003] Various plasma processing apparatuses have been developed for continuous plasma processing while flowing air. For example, Patent Document 1 discloses a plasma generator in which two or more layers of plasma generation units are stacked, wherein the plasma generation units are provided with flat first and second electrodes facing each other with a gap therebetween. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2022-190472 Summary of the Invention Problem to be Solved by the Invention

[0005] Conventional plasma processing apparatuses stack a plurality of layers of plasma generation units to increase the contact area with air, but this arrangement has a problem that the apparatus increases in size.

[0006] In view of such a background, an object of the present invention is to provide a plasma processing apparatus that can improve plasma generation efficiency and can be reduced in size. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present invention provides a plasma generation unit that generates plasma and includes at least a dielectric layer and a pair of electrode layers provided on the front and back surfaces of the dielectric layer; a power supply unit that applies an AC voltage to the pair of electrode layers; and a gas flow unit that flows gas in a cylindrical shape in the space outside the plasma generation unit in order to process the gas with plasma, wherein the plasma generation unit is installed spirally in the axial direction inside the gas flow unit.

[0008] According to the present invention, the plasma generation unit is installed in a spiral shape inside the gas flow section. This ensures a large contact area with the air, thereby increasing the plasma generation efficiency and enabling miniaturization.

[0009] Furthermore, it is preferable that the plasma generation section is spirally wound around a central member installed axially within the gas flow section.

[0010] According to the present invention, the plasma generation section can be easily made into a spiral shape.

[0011] Furthermore, it is preferable that the gas flow section has a pair of support members installed at both ends and equipped with communication holes that communicate with the inside and outside of the gas flow section, and that the support members support both ends of the central member.

[0012] According to the present invention, the central member can be easily supported within the gas flow section.

[0013] Furthermore, it is preferable that the electrode layer has through holes through which the dielectric layer is exposed. According to the present invention, the plasma generated near the cross-section of the electrode layer within the through holes can be used to plasma treat the gas flowing outside the plasma generation section.

[0014] It is also preferable that a mask layer is provided on the outer side of the electrode layer. According to the present invention, the electrode layer can be protected by the mask layer. Effects of the Invention

[0015] According to the plasma processing apparatus of the present invention, plasma generation efficiency can be improved and size reduction can be achieved. Brief Description of Drawings

[0016] [Figure 1] It is a perspective view showing the plasma processing apparatus according to the first embodiment of the present invention. [Figure 2] It is a perspective sectional view showing the plasma processing apparatus according to the first embodiment. [Figure 3] It is a perspective view showing the support member according to the first embodiment. [Figure 4] It is a perspective view showing the plasma generation unit according to the first embodiment. [Figure 5] It is a perspective view showing the plasma generation unit according to the first embodiment. [Figure 6] It is a sectional view showing the plasma generation unit according to the first embodiment. [Figure 7] It is a perspective view showing the plasma generation unit according to the second embodiment of the present invention. [Figure 8] It is a perspective view showing the plasma generation unit according to the third embodiment of the present invention. Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail, but the embodiments of the present invention are not limited to the embodiments described below. Each embodiment can be applied in appropriate combination. In addition, directions such as "up and down" used in the description are for convenience of description, and do not limit the direction of the present invention.

[0018] <First Embodiment> The plasma processing apparatus of the present embodiment, for continuously performing plasma processing on gas, comprises: a plasma generation unit of multilayer structure having a dielectric layer, an electrode layer and a mask layer; a power supply unit capable of applying an alternating voltage between a pair of electrode layers; and a gas flow unit capable of flowing gas into a space outside the plasma generation unit. In dielectric barrier discharge, a dielectric layer is provided between two electrode layers, and by applying an alternating voltage between the two electrode layers, plasma can be generated in the dielectric layer sandwiched between the two electrode layers.

[0019] As shown in FIG. 1 and FIG. 2, the plasma processing apparatus 100 according to the first embodiment includes a plasma generation unit 10, a gas flow unit 20, a central member 30, support members 40, 40, and a power supply unit (not shown).

[0020] The plasma generation unit 10 has a strip shape and is spirally wound a plurality of times around the outer circumferential surface of the central member 30. As shown in FIG. 4 and FIG. 5, the plasma generation unit 10 includes a dielectric layer 11, an upper electrode 12, a lower electrode 13, an upper mask layer 14, and a lower mask layer 15. The thickness of the plasma processing apparatus 100 may be appropriately set according to the application, for example, 0.2 to 10 mm is preferable, and 0.3 to 8 mm is more preferable. The plasma generation unit 10 is a thin film member and has flexibility.

[0021] As shown in FIG. 4 to FIG. 6, the dielectric layer 11 is a layered member disposed between the upper electrode 12 and the lower electrode 13. For the material of the dielectric layer 11, an insulating material with a high dielectric breakdown voltage is used so that discharge does not easily occur between the upper electrode 12 and the lower electrode 13. In addition, since the material of the dielectric layer 11 will be exposed to the generated plasma, it is preferably a material having durability against active substances generated in the plasma. It is preferable that the material of the dielectric layer 11 is mainly a material selected from glass, ceramics and synthetic resin. The term "mainly" means that the component composition is 50% by mass or more (the same applies hereinafter).

[0022] Examples of glass include soda-lime glass (soda glass), borosilicate glass, quartz glass, lead glass, and oxide glass. Synthetic resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include general-purpose resins such as polyolefins, polystyrene, polyvinyl acetate, polyurethane, polylactic acid, ABS resin, AS resin, acrylic resin, polyvinyl chloride, and polyvinylidene chloride; engineering plastics such as polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester, and cyclic polyolefin; polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, liquid crystal polymer, polyetheretherketone, polyimide, polyamideimide, polyetherimide, fluororesins, unsaturated polyester resins, and polyurethane resins. Among these synthetic resins, silicone-based resins, which have excellent durability, are particularly preferred. The thickness of the dielectric layer 11 is not particularly limited, but to achieve lightness and miniaturization, it is preferably 0.1 mm to 5.0 mm, more preferably 0.1 mm to 3.0 mm, and even more preferably 0.1 to 1.0 mm.

[0023] As shown in Figures 4 and 5, the upper electrode (electrode layer) 12 and the lower electrode (electrode layer) 13 are layered members installed on the front and back surfaces of the dielectric layer 11. The upper electrode 12 and the lower electrode 13 are each provided with through holes 16 that penetrate in the thickness direction. In this embodiment, the through holes 16 are elongated and there are five of them, but the shape and number are not limited. The through holes 16 may also be omitted.

[0024] The upper electrode (electrode layer) 12 and the lower electrode (electrode layer) 13 are formed of a conductive material, and can be made of a metal plate (including metal foil), conductive paint, conductive polymer, conductive film, etc. The thickness of the upper electrode 12 and the lower electrode 13 is not particularly limited, but in order to provide a flexible, lightweight, and compact processing apparatus, they are preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm, respectively.

[0025] The dielectric layer 11, the upper electrode 12, and the lower electrode 13 may be laminated without using an adhesive, or they may be bonded together with an adhesive. The adhesive is preferably made of a material that is resistant to active substances generated in the plasma. Adhesives include epoxy, acrylic, urethane, phenol, urea, silicone, cyanoacrylate, rubber, and vinyl acetate types. Among these, silicone adhesives and UV-curing epoxy adhesives are preferred in terms of durability, with silicone adhesives being more preferred. The thickness of the adhesive is preferably 0.01 to 0.2 mm, and more preferably 0.01 to 0.1 mm.

[0026] The upper mask layer (mask layer) 14 and the lower mask layer (mask layer) 15 are components installed on the outside of the upper electrode 12 and the lower electrode 13, respectively, as shown in Figure 5. More specifically, the upper mask layer 14 is installed on the upper surface of the upper electrode 12. The lower mask layer 15 is installed on the lower surface of the lower electrode 13. The upper mask layer 14 and the lower mask layer 15 are each provided with through holes 17. In this embodiment, the through holes 17 are elongated and there are five of them, but the shape and number are not limited. The through holes 17 may be omitted.

[0027] As shown in Figure 6, the through-hole 17 has the same shape as the through-hole 16 and is in communication with it. The dielectric layer 11 is exposed to the outside through the through-holes 16 and 17. In other words, the surface of the dielectric layer 11 is exposed to the outside at multiple locations where the through-holes 16 and 17 are formed. In addition, the hole walls (cross-sections) 16a and 17a of the through-holes 16 and 17 are also exposed to the outside, respectively.

[0028] The upper mask layer 14 and the lower mask layer 15 are made of an insulating material. Furthermore, it is preferable that the hardness of the upper mask layer 14 and the lower mask layer 15 be equal to or less than the hardness of the upper electrode 12 and the lower electrode 13. The plasma generation unit 10 is a thin component and therefore difficult to handle; however, the provision of the upper mask layer 14 and the lower mask layer 15 improves handling. On the other hand, considering that the plasma generation unit 10 is installed in a curved manner along the gas flow section 20, it is preferable that the upper mask layer 14 and the lower mask layer 15 have a hardness that makes them easy to install along the gas flow section 20 and also improves handling. The thicknesses of the upper mask layer 14 and the lower mask layer 15 are not particularly limited, but in order to provide a flexible, lightweight, and compact processing apparatus, they are preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm, respectively. The thicknesses of the upper mask layer 14 and the lower mask layer 15 can be set as appropriate, but in this embodiment, they are formed to be greater than the thicknesses of the upper electrode 12 and the lower electrode 13.

[0029] Furthermore, the outer edges of the upper electrode 12 and the lower electrode 13 may be sealed with an insulator (not shown) to prevent their outer edges from being exposed to the outside environment and deteriorating over time, and to prevent discharge from occurring through the outer edges other than the through-hole 16. Similarly, the upper mask layer 14 and the lower mask layer 15 may have their outer edges sealed with an insulator (not shown) to prevent them from being exposed to the outside environment and deteriorating over time due to reactions with external substances, and to prevent discharge from occurring through the outer edges other than the through-holes 17.

[0030] When the longitudinal direction of the through-holes 16 and 17 is parallel to the direction of gas flow, the resistance to gas flow is reduced, and the gas flow becomes smoother. On the other hand, when the longitudinal direction of the through-holes 16 and 17 is perpendicular to the direction of gas flow, the resistance to gas flow increases, the gas flow is disturbed, and the gas is agitated.

[0031] The shape, number, and orientation of the through-holes 16 and 17 relative to the gas flow can be appropriately selected and implemented according to the purpose of the plasma treatment, the effects of the plasma treatment, etc. Furthermore, the shape of the through-holes may differ between the front and back sides of the plasma generation unit 10. Alternatively, through-holes may be provided on the front side of the plasma generation unit 10, but not on the back side.

[0032] As shown in Figures 1 and 2, the gas flow section 20 is made of an insulator and has a cylindrical shape. The gas flow section 20 is a component that can flow gas into the space outside the plasma generation section 10 in order to continuously process the gas with plasma. The gas flow section 20 allows gas to flow in from one end and along the axial direction, and discharges the gas from the other end. There are no particular restrictions on the gas flow section 20 as long as it is a component that can supply gas along the axial direction around the plasma generation section 10, allow the gas to pass through the space outside the plasma generation section 10, and then discharge the plasma-treated gas.

[0033] As a method for flowing the gas, any known method can be appropriately selected and used. As a drive device for flowing the gas, known devices such as centrifugal fans (sirocco fans, radial fans, turbo fans, etc.), axial flow fans (propeller fans, etc.), mixed flow fans (line fans, etc.), cross flow fans, and blowers can be used as appropriate.

[0034] The central member 30 is a cylindrical member on which the plasma generation unit 10 is installed. The central member 30 is sized to be inserted into the gas flow unit 20. The central member 30 may be a hollow tube. Furthermore, the central member 30 may have a rectangular cross-section (prismatic or tubular) rather than a circular cross-section.

[0035] As shown in Figure 1, the support members 40 are inserted into both ends of the gas flow section 20. As shown in Figure 3, the support members 40 consist of a main body 41, a fitting portion 42, and communication holes 43. The main body 41 is a cylindrical portion. The main body 41 is sized to fit inside the gas flow section 20. The fitting portion 42 is the portion into which the central member 30 is fitted. The communication holes 43 are holes that communicate with the inside and outside of the gas flow section 20. Multiple communication holes 43 are provided around the fitting portion 42. Gas flows into the gas flow section 20 through the communication holes 43.

[0036] Because the plasma processing apparatus 100 experiences temperature changes during use, there is a concern that problems such as delamination may occur over time if there are large differences in the coefficients of thermal expansion between the materials constituting the multilayer structure. Therefore, it is preferable that the materials and adhesives constituting the dielectric layer 11, upper mask layer 14, and lower mask layer 15, which are laminated with the upper electrode 12 and lower electrode 13, are made of highly flexible materials that can follow the dimensional changes of the upper electrode 12 and lower electrode 13. As such materials, synthetic resin materials are preferred, and it is even more preferable to select and use an appropriate material from among synthetic resin materials.

[0037] To manufacture the plasma generation unit 10 of the plasma processing apparatus 100 of this embodiment, materials such as a dielectric layer 11, an upper electrode 12, a lower electrode 13, an upper mask layer 14, and a lower mask layer 15 are laminated together. Known methods for laminating each layer include pressure bonding, heat bonding, and adhesive application, which can be selected and used as appropriate. Methods for forming through holes 16 and 17 in the upper electrode 12, lower electrode 13, upper mask layer 14, and lower mask layer 15 include punching and etching, which can be selected and used as appropriate.

[0038] The power supply unit (not shown) applies an AC voltage between the upper electrode 12 and the lower electrode 13, which face each other with the dielectric layer 11 in between. The power supply unit is not particularly limited as long as it can apply an AC voltage of a predetermined voltage at a predetermined frequency to each electrode of the plasma generation unit 10; known power supply devices can be used. The frequency of the AC voltage is preferably 50Hz to 30MHz, and more preferably 50Hz to 100kHz. Furthermore, the AC voltage is preferably 0.1 to 50kV, and more preferably 0.2 to 10kV.

[0039] <Effects and Effects> Next, the effects of the plasma processing apparatus 100 according to this embodiment will be described. When an AC voltage is applied between the upper electrode 12 and the lower electrode 13 that sandwich the dielectric layer 11, plasma is generated within the dielectric layer 11 sandwiched between them. Furthermore, plasma is also generated near the holes (cross-sectional portions) 16a and 17a of the through holes 16 and 17. When an AC voltage is applied between two electrode layers, plasma is generally more likely to be generated from the protruding edges of the electrode layers than from the flat surfaces of the electrode layers. Therefore, as shown in Figure 6, in the plasma generation unit 10, more plasma is more likely to be generated near the holes (cross-sectional portions) 16a and 17a within the through holes 16 and 17 than inside the dielectric layer 11 between the two electrode layers.

[0040] While applying an AC voltage between each electrode layer flanking the dielectric layer 11, the gas to be processed by the plasma flows on both sides of the plasma generation unit 10. The gas is processed by the plasma generated along the surface of the plasma generation unit 10, near the surface of the dielectric layer 11 exposed to the outside within the through holes 16 and 17, and near the hole walls (cross-sections) 16a and 17a within the through holes 16 and 17. In particular, the gas is processed more strongly by the plasma generated near the hole walls (cross-sections) 16a and 17a of the through holes 16 and 17.

[0041] As mentioned above, the through holes 16 and 17 may be omitted. In this case, when an AC voltage is applied between the two electrode layers sandwiching the dielectric layer 11, plasma is generated beyond the dielectric layer 11, outside the upper mask layer 14 and the lower mask layer 15. The gas is then processed by this plasma.

[0042] The functions exhibited by plasma treatment of a gas using the plasma treatment apparatus 100 of this embodiment include sterilization, virus inactivation, deodorization, surface modification, and decomposition of chemical substances. The mechanism by which these functions are exhibited is thought to be that plasma treatment generates reactive oxygen species such as singlet oxygen, hydrogen peroxide, OH radicals, peroxide radicals, and ozone in the gas, and these then kill target microorganisms or decompose and modify chemical substances through oxidation reactions. Examples of microorganisms include various bacteria, viruses, and fungi.

[0043] In the plasma processing apparatus 100 of this embodiment, the plasma-treated gas is sterilized and deodorized by the reactive oxygen species generated by the plasma, which kill microorganisms present in the gas and decompose chemical substances. Furthermore, in the plasma processing apparatus 100 of this embodiment, reactive oxygen species are present (residual) in the plasma-treated gas. Therefore, by blowing the plasma-treated gas generated by the plasma processing apparatus of this embodiment onto an object, microorganisms present in the object are killed or chemical substances are decomposed, thereby sterilizing and deodorizing the object.

[0044] The plasma processing apparatus 100 of this embodiment can be used in many industrial fields such as medicine (fiberscopes, endoscopes, various small cameras, etc.), housing, civil engineering, construction, agriculture, fisheries, livestock farming, food processing, transportation, storage, and retail for purposes such as deodorization, odor removal, sterilization and disinfection, and air purification.

[0045] According to the plasma processing apparatus 100 of this embodiment described above, the plasma generation unit 10 is installed spirally in the axial direction of the gas flow unit 20. This ensures a large contact area with air, allowing for continuous and efficient plasma generation, while also enabling miniaturization. Furthermore, the installation area of ​​the plasma generation unit 10 can be increased as the number of turns of the plasma generation unit 10 increases. In other words, the installation area of ​​the plasma generation unit 10 per unit length in the axial direction can be increased. This further enhances the plasma generation efficiency.

[0046] Furthermore, when polyimide is used as the dielectric layer 11, the manufacturing process for commonly used flexible substrates can be utilized, thus significantly reducing manufacturing costs.

[0047] Furthermore, the plasma generation unit 10 is equipped with through holes 16 and 17 through which the dielectric layer 11 is exposed. This allows the plasma generated near the hole walls (cross-sections) 16a and 17a of the electrode layer within the through holes 16 and 17 to efficiently plasma-treat the gas flowing outside the plasma generation unit 10.

[0048] Furthermore, an upper mask layer 14 and a lower mask layer 15 may be provided on the outside of the upper electrode 12 and lower electrode 13. For this purpose, it is desirable to make the plasma generation unit 10 very thin and flexible to improve bending performance. However, this presents a problem in that it becomes difficult to handle during assembly. Also, since the upper electrode 12 and lower electrode 13 are made of conductive materials such as conductive metals or conductive dielectrics, they may be corroded by liquids or gases. For example, the upper electrode 12 and lower electrode 13 will oxidize with highly oxidizing gases and be corroded by sulfuric acid or hydrochloric acid. Additionally, although the plasma generation unit 10 is installed along the shape of the central member 30, if only the upper electrode 12 and lower electrode 13 are present without the upper mask layer 14 and lower mask layer 15, problems arise such as wrinkles forming in the metal constituting the electrodes or gaps forming between them and the dielectric layer 11, especially if the electrodes are made of thin metal. If a gap forms between the upper electrode 12 and the lower electrode 13 and the dielectric layer 11, it can cause abnormal discharge. In this respect, according to this embodiment, the upper mask layer 14 and the lower mask layer 15 can protect the upper electrode 12 and the lower electrode 13, and the plasma generation unit 10 becomes easier to handle, improving workability and assembly. Furthermore, by providing the upper mask layer 14 and the lower mask layer 15, it can be installed on the central member 30 without the formation of wrinkles or gaps. In addition, when multiple pairs of electrodes are provided to create a multi-stage system, the upper mask layer 14 and the lower mask layer 15 also become part of the dielectric that constitutes the barrier discharge, so even if gaps are created during installation, abnormal discharge is less likely to occur. Depending on the situation, the same effect can be obtained by using either the upper or lower mask layer.

[0049] Furthermore, the central member 30 may be omitted, but the layered plasma generation unit 10 can be installed by spirally winding it around the central member 30. This allows the plasma generation unit 10 to be easily installed inside the gas flow unit 20. In the plasma generation unit 10, since the distance between each electrode is constant, it is more resistant to vibration than structures in which the electrodes themselves are spirally wound, and problems such as abnormal discharge due to assembly variations can be suppressed.

[0050] Furthermore, by providing the support members 40, 40, the central member 30 can be easily supported inside the gas flow section 20.

[0051] Furthermore, according to this embodiment, if the characteristics of the plasma generation unit 10 change, the initial characteristics can be obtained again by replacing only the plasma generation unit 10. In addition, since the gas flow unit 20 does not depend on plasma generation, the plasma generation of the plasma generation unit 10 can be tested before assembly. This makes it possible to improve the yield during the manufacturing of the plasma processing apparatus 100.

[0052] <Second Embodiment> Figure 7 is a perspective view showing a plasma generation unit according to a second embodiment of the present invention. The plasma generation unit 10A according to the second embodiment differs from the first embodiment in that it does not have an upper mask layer 14. As in the plasma processing apparatus according to the second embodiment, the mask layer may be provided only on one side of the plasma generation unit 10A.

[0053] <Third Embodiment> Figure 9 is a perspective view showing a plasma generation unit according to a third embodiment of the present invention. The plasma generation unit 10B according to the third embodiment differs from the first embodiment in that it does not have an upper mask layer 14 and a lower mask layer 15. The upper mask layer 14 and the lower mask layer 15 may be omitted, as in the plasma processing apparatus according to the third embodiment. In other words, by configuring the plasma generation unit 10B with a dielectric layer 11, an upper electrode 12 and a lower electrode 13, it is possible to further miniaturize the unit and reduce the number of parts.

[0054] Furthermore, as in the second and third embodiments, by omitting both or one of the upper mask layer 14 and the lower mask layer 15, the upper electrode 12 and the lower electrode 13 can be brought into direct contact with the gas, allowing the plasma and gas to come into contact at the ends of the electrodes and the plasma gas to be easily extracted.

[0055] Although embodiments of the invention have been described above, the design can be modified as appropriate without violating the spirit of the present invention. For example, the central member 30 may be a hollow cylindrical shape. This allows for weight reduction and increased bending rigidity. The central member 30 may be an insulator, but a conductor may also be used. If the central member 30 is a conductor, it will be at the same potential as the lower surface of the electrodes of the plasma generation unit 10, and the inductance of the electrodes, which increases when the plasma generation unit 10 is wound in a spiral shape, can be reduced. [Explanation of symbols]

[0056] 10 Plasma generation unit 11 Dielectric layer 12 Upper layer electrode (electrode layer) 13 Lower electrode (electrode layer) 14 Upper mask layer 15 Lower mask layer 16 Through holes 17 Through hole 20 Gas fluid section 30 Central member 40 Support member 100 Plasma Processing Equipment

Claims

1. A plasma generation unit that generates plasma, comprising at least a dielectric layer and a pair of electrode layers provided on the front and back surfaces of the dielectric layer, A power supply unit that applies an AC voltage to the pair of electrode layers, To process a gas with plasma, the system has a gas flow section that is cylindrical and flows the gas through the space outside the plasma generation section, The plasma processing apparatus is characterized in that the plasma generation unit is installed spirally in the axial direction inside the gas flow unit.

2. The plasma processing apparatus according to claim 1, characterized in that the plasma generation section is spirally wound around a central member installed axially inside the gas flow section.

3. The gas flow section has a pair of support members installed at both ends and equipped with communication holes that communicate with the inside and outside of the gas flow section, The plasma processing apparatus according to claim 2, characterized in that the support member supports both ends of the central member.

4. The plasma processing apparatus according to claim 1 or 2, characterized in that the electrode layer has through holes through which the dielectric layer is exposed.

5. The plasma processing apparatus according to claim 1 or 2, characterized in that it comprises a mask layer on the outside of the electrode layer.

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