JP2006100078A - Plasma torch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma torch which does not generate an outgas even in a super-high vacuum environment, and which is commonly usable as a migrating type and a nonmigrating type. <P>SOLUTION: This plasma torch has a conductive anode 10 of a nearly cylindrical shape, an insulating tube 20 composed of silica or machinable ceramics inserted into the inside of the anode 10, and a rod shaped cathode 30 inserted into the inside of the insulating tube 20 so as not to be contacted with the anode 10, and has a constitution that the plasma is formed by respectively applying a positive voltage and a negative voltage to the anode 10 and the cathode 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma torch, and more particularly to a plasma torch that can be used in an ultra-high vacuum chamber.

According to the plasma heat source, for example, a high temperature of 5000 to 30000 ° C. and a high energy density of about 100 kW / cm ² can be easily obtained, and heating using this can easily control the heating atmosphere and the heating state. . For this reason, it is used in metallurgy such as heat evaporation of metals, metallurgy such as metal reduction and refining, material processing such as welding and cutting, chemical industry such as acetylene coal and gas cracking furnace, and other wide fields. .

Plasma torches can be broadly classified into transitional and non-transitional types.
FIGS. 3A and 3B are schematic configuration diagrams of a transfer type and a non-transfer type plasma torch according to a conventional example, respectively.
As shown in FIG. 3A, the transition type plasma torch is assembled by inserting a rod-shaped internal electrode 3 serving as a cathode into the central portion inside the substantially cylindrical plasma chip 1. By applying a positive voltage to the object to be heated S and a negative voltage to the internal electrode 3, discharge is generated between the object to be heated S and the internal electrode 3 to generate plasma. At this time, the plasma is heated by supplying a current to the article S to be heated.

  On the other hand, as shown in FIG. 3B, the non-transition type plasma torch has the same structure as the transition type with the internal electrode 3 inserted in the central part inside the substantially cylindrical plasma chip 1. However, plasma gas G is further supplied from between the plasma chip 1 and the internal electrode 3, and a positive voltage is applied to the plasma torch 1 and a negative voltage is applied to the internal electrode 3. To discharge and generate plasma. The article to be heated S is heated using the obtained plasma gas as a medium.

The transfer-type plasma torch has the advantage of high energy efficiency because current flows through the object to be heated and generates Joule heat, but it generates plasma, and plasma is generated until the object to be heated melts and becomes conductive. An electrode for holding is required and is not suitable for heating and melting the insulator.
On the other hand, since the non-transfer type plasma torch does not flow current to the object to be heated, it can generate plasma without being affected by the material of the object to be heated, and has the advantage of high startability and stability of plasma. is there.

By the way, the non-transfer type plasma torch has two electrodes of an anode (plasma chip) and a cathode (internal electrode) in the torch, and these need to be insulated from each other. For this reason, in the conventional non-migration type plasma torch, a polymer insulating material such as bakelite is used in order to ensure the insulation between the two electrodes.
Due to the above-described polymer insulating material and other torch constituent materials, outgassing occurs when a conventional non-migration type plasma torch is used in an ultra-high vacuum environment.
For example, in a supersonic free jet PVD (physical vapor deposition) apparatus, when nanoparticles are generated from an evaporation source by plasma generated by a plasma torch, the obtained nanoparticles are contaminated with outgas.

  The problem to be solved is that the conventional non-migration type plasma torch causes problems such as generation of outgas in an ultra-high vacuum environment.

  The plasma torch according to the present invention includes a substantially cylindrical conductive anode, an insulating tube made of quartz or machinable ceramic inserted inside the anode, and an inner side of the insulating tube so as not to contact the anode. It has a rod-like cathode inserted therein, and plasma is formed by applying a positive voltage and a negative voltage to the anode and the cathode, respectively.

  The plasma torch according to the present invention includes an insulating tube made of quartz or machinable ceramic inserted inside the anode, and a rod-like cathode inserted inside the insulating tube so as not to contact the anode. Plasma is formed by applying a positive voltage and a negative voltage to the anode and the cathode, respectively.

  The plasma torch according to the present invention is preferably a plasma supplied to the cathode by positioning a relative position of the anode and the cathode between the anode and the cathode in the vicinity of the tip of the cathode. A ceramics plasma gas distributor is provided to distribute the gas evenly.

In the plasma torch according to the present invention, preferably, the cathode has, as an internal structure, a first hollow portion disposed in the center, a second hollow portion disposed on an outer periphery of the first hollow portion, It has a three-layer structure having a third hollow portion arranged on the outer periphery of the second hollow portion.
More preferably, the first hollow portion of the cathode is a plasma gas supply pipe.
More preferably, the second hollow portion of the cathode is a cooling medium introduction tube, and the third hollow portion of the cathode is a cooling medium outlet tube.

  In the plasma torch of the present invention, the anode preferably has a built-in cooling pipe.

  The plasma torch of the present invention preferably uses a VCR joint and / or an ICF flange as a vacuum seal.

  In the plasma torch of the present invention, preferably, a plasma is formed by applying a positive voltage and a negative voltage to the anode and the cathode, respectively, and an object to be heated and a positive voltage are applied to the cathode, respectively. And a method of forming a plasma by applying a negative voltage can be switched or used together.

  The plasma torch according to the present invention includes a substantially cylindrical conductive anode, an insulating tube made of quartz or machinable ceramic inserted inside the anode, and the insulating tube so as not to contact the anode. A rod-shaped cathode inserted inside, and a holding tube disposed on an outer periphery of the anode, the holding tube being electrically connected to the cathode and mechanically holding the cathode; A holding member; a second holding member electrically connected to the anode to mechanically hold the cathode; and the anode and the cathode mechanically through the first holding member and the second holding member. A third holding member for holding, and at least a space between the first holding member and the second holding member and between the second holding member and the third holding member is melted in the ceramic insulating member. And the first holding member, the second holding member and the third holding member are integrated while being insulated from each other, and a VCR joint and / or as a vacuum seal of the anode, the cathode and the holding tube An ICF flange is used, and plasma is formed by applying a positive voltage and a negative voltage to the plasma chip and the internal electrode, respectively.

The plasma torch according to the present invention includes an insulating tube made of quartz or machinable ceramic inserted inside the anode, a rod-like cathode inserted inside the insulating tube so as not to contact the anode, and an outer periphery of the anode. And a holding tube disposed in the section.
The holding tube includes a first holding member that is electrically connected to the cathode and mechanically holds the cathode, a second holding member that is electrically connected to the anode and mechanically holds the cathode, and a first holding member And a third holding member for mechanically holding the anode and the cathode via the second holding member, and at least between the first holding member and the second holding member and between the second holding member and the third holding member. Are joined to the ceramic insulating member by welding, and the first holding member, the second holding member and the third holding member are integrated while being insulated from each other.
Also, VCR joints and / or ICF flanges are used as vacuum seals for the anode, cathode and holding tube.
In the above configuration, plasma is formed by applying a positive voltage and a negative voltage to the anode and the cathode, respectively.

The plasma torch of the present invention uses an insulating tube made of quartz or machinable ceramics to insulate the anode and the cathode, and does not use a polymer insulating material, so it does not generate outgas even in an ultra-high vacuum environment. Can be used for
In addition, the plasma torch of the present invention has a holding tube that holds the entire plasma torch on the outer periphery of the anode and applies a predetermined potential to the anode and the cathode, so that it does not generate outgas and supports an ultra-high vacuum environment. can do.

  Embodiments of a plasma torch according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a partial cross-sectional structure of a plasma torch according to the present embodiment. FIG. 2 is an enlarged view of a portion A in FIG.
The plasma torch according to this embodiment includes a substantially cylindrical conductive anode 10, an insulating tube 20 made of quartz or machinable ceramic inserted inside the anode, and an insulating tube 20 that does not contact the anode 10. And a rod-like cathode 30 inserted inside.

  The anode 10 is assembled by connecting a substantially cylindrical anode first member 10a and an anode second member 10b provided at the tip of the anode first member 10a via a copper sealant 10c. The anode first member 10a and the anode second member 10b are made of a metal material such as stainless steel, copper, or tungsten, for example.

The anode first member 10a has a thick, substantially cylindrical shape and has a partially hollow structure, and a water cooling system 11 connected to the cooling water inlet 11a and the cooling water outlet 11b is embedded therein. Then, it is cooled by the cooling water 11f.
The cooling system 11 can efficiently cool the anode 10 that is heated by plasma generation.

The anode second member 10b is provided so as to cover one end of the substantially cylindrical anode first member 10a, and has an opening 10h at the center thereof. The inner diameter of the second anode member 10b is, for example, a structure that is gradually narrowed in several steps from the inner diameter of the first anode member 10a. The outer diameter of the second anode member 10b is, for example, the first anode member. It has a tapered shape that is smoothly narrowed from the outer diameter of 10a toward the tip.
In this manner, the diameter of the anode 10 is narrowed near the tip of the cathode 30.

  The insulating tube 20 is made of quartz or machinable ceramic, and is made of a material that does not substantially emit outgas even in an ultra-high vacuum environment. Quartz or machinable ceramics is made of a material that does not substantially emit outgas, and can be prepared at a relatively low cost to form a tubular shape for use in this embodiment. In particular, quartz tubes of various sizes are commercially available, and an insulating tube of a desired size can be easily obtained.

The machinable ceramics described above are ceramics that can be easily machined, and are broadly classified into those containing a lamellar structure such as mica inside and those containing many fine cracks structurally. . The former includes, for example, mica crystallized glass such as KMg ₃ AlSi ₃ O ₁₀ F ₂ fluorine phlogopite, and the latter includes aluminum titanate.

  The outer diameter of the insulating tube 20 is sized to match the inner diameter of the anode 10 including the anode first member 10a and the anode second member 10b, and penetrates through the anode first member 10a and passes through the anode second member 10b. Is inserted inside the anode 10 so as to be locked by a step-like structure inside.

  The cathode 30 is assembled by connecting a cathode first member 30a provided at a tip portion and a cathode second member 30b supporting the cathode first member 30a. The cathode first member 30a and the cathode second member 30b are made of, for example, a metal material such as stainless steel, copper, or tungsten.

The cathode first member 30 a is supported so that the root is supported by the cathode second member 30 b and the vicinity of the tip is locked to the gas distributor 21. The gas distributor 21 is fitted and provided at the tip of the insulating tube 20 so as to be locked by a stepped structure inside the anode second member 10b.
The gas distributor 21 is made of, for example, a non-polymeric insulating material such as ceramic, is made of a material that does not substantially emit outgas even in an ultra-high vacuum environment, and is located between the anode and the cathode near the cathode tip. In addition, the anode and the cathode are positioned relative to each other so that the anode and the cathode are not in contact with each other to prevent a short circuit between them. Further, the gas distributor 21 is provided with a fine opening, and the plasma gas supplied to the cathode can be evenly distributed.

As the internal structure, the cathode second member 30b is disposed at the outer periphery of the first hollow portion 31 disposed at the center, the second hollow portion 32a disposed at the outer periphery of the first hollow portion, and the second hollow portion 32a. The first hollow portion 31 in the cathode second member 30b is a plasma gas supply pipe. From here, the plasma gas 31 f can be supplied to the tip portions of the anode 10 and the cathode 30 via the gas distributor 21.

The second hollow portion 32a in the cathode second member 30b is an introduction pipe for cooling water 32f as a cooling medium, and the third hollow section 32b is a cooling water outlet pipe.
The cathode inserted into the insulating tube 20 having a low thermal conductivity by having a cooling system that is separated from the cooling system 11 of the anode 10 as the cooling system 32 composed of the second hollow portion 32a and the third hollow portion 32b. 30 can be efficiently cooled.

Further, in the plasma torch of the present embodiment, the holding tube 40 is disposed on the outer peripheral portion of the anode 10.
The holding tube 40 includes a first holding member 41 that is electrically connected to the cathode 30 and mechanically holds the cathode, and a second holding member 42 that is electrically connected to the anode 10 and mechanically holds the cathode. A third holding member 43 that mechanically holds the anode 10 and the cathode 30 via the first holding member 41 and the second holding member 42, and at least between the first holding member 41 and the second holding member 42. The second holding member 42 and the third holding member 43 are joined to the ceramic insulating members (44, 45) by welding so that the first holding member 41, the second holding member 42 and the third holding member 43 are insulated from each other. While being integrated.

As described above, the plasma torch according to the present embodiment has a structure in which the anode and the cathode are made of a metal material such as stainless steel and are insulated by the insulating tube.
Furthermore, the plasma torch in this embodiment uses a VCR joint and / or an ICF flange as a vacuum seal.

At the tip portions of the anode 10 and the cathode 30, the inner wall of the anode second member 10b and the tip of the cathode first member 30a are separated by a predetermined distance, and a plasma gas 31f is supplied to this region, and the anode and cathode By applying a positive voltage and a negative voltage respectively to the plasma, a plasma is generated by discharge between the anode and the cathode. That is, it is a so-called non-migration type plasma torch.
The obtained plasma can be supplied to the outside of the plasma torch from the opening 10h at the tip of the anode.

As described above, the plasma torch according to the present embodiment does not use a high-molecular insulating material such as bakelite to insulate them as in the conventional plasma torch. There is virtually no outgassing.
In addition, by holding the entire plasma torch on the outer periphery of the anode and having a holding tube for applying a predetermined potential to the anode and the cathode, it is possible to cope with an ultrahigh vacuum environment without generating outgas.
Therefore, for example, in a supersonic free jet PVD apparatus, when nanoparticles are generated from an evaporation source by plasma generated by a plasma torch, the nanoparticles are generated without being contaminated by outgas by using the plasma torch according to the present embodiment. be able to. Thus, by using the plasma torch in the present embodiment in an ultra-high vacuum environment or a gas replacement atmosphere, it is possible to prevent impurities from being mixed into the heating object.
Moreover, the plasma torch according to the present embodiment can be used in a wide range of atmospheric pressures from an ultrahigh vacuum environment of about 10 ⁻¹⁰ torr to atmospheric pressure.

  In addition, the plasma torch according to the present embodiment is suitable for heating under conditions in which a minute amount of gas such as toxic gas generated by heating evaporation such as a CVD (chemical vapor deposition) apparatus or a waste treatment apparatus is not allowed to leak out of the apparatus. Can be applied.

The plasma torch in this embodiment is, for example, a non-transition type in which a positive voltage and a negative voltage are respectively applied to an anode and a cathode, and a positive voltage and a negative voltage are respectively applied to an object to be heated and a cathode. It can be operated by switching between the transfer type that forms plasma by applying it, or by using the two types together.
By switching or using these in combination, it can be used regardless of the material of the transfer type energy efficiency and the non-transfer type non-heated material. It is possible to enjoy the advantages of heating the target object more efficiently. In both the transfer type and the non-transfer type, outgas is not substantially generated when used in an ultra-high vacuum environment.

The present invention is not limited to the above description.
For example, in the above-described embodiment, the first to third holding members are integrated while being insulated from each other via the insulating member as the holding tube disposed on the outer periphery of the anode. A configuration that enables a predetermined potential to be applied to the anode and the cathode, and enables the anode and the cathode to be used in an ultra-high vacuum environment without using a polymer insulating material amount while realizing a cooling system and a gas supply system. It only has to be.
In addition, various modifications can be made without departing from the scope of the present invention.

The plasma torch of the present invention can be applied to a heating source used in a high vacuum environment or an environment with high gas tightness and low gas leakage. For example, plasma for generating nanoparticles from an evaporation source in a supersonic free jet PVD apparatus. Applicable to torch.
Furthermore, it can be applied as a heating means in other various PVD apparatuses, CVD apparatuses, reduced pressure spraying apparatuses, and the like.

FIG. 1 is a schematic configuration diagram showing a partial cross-sectional structure of a plasma torch according to an embodiment of the present invention. FIG. 2 is an enlarged view of a portion A in FIG. FIGS. 3A and 3B are schematic configuration diagrams of a transfer type and a non-transfer type plasma torch according to a conventional example, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Anode 10a ... Anode 1st member 10b ... Anode 2nd member 10c ... Sealing agent 10h ... Opening part 11 ... Cooling system 11a ... Cooling water inlet 11b ... Cooling water outlet 11f ... Cooling water 20 ... Insulating pipe 21 ... Gas Tributor 30 ... Cathode 31 ... First hollow part 31f ... Plasma gas 32 ... Cooling system 32a ... Second hollow part 32b ... Third hollow part 32f ... Cooling water 40 ... Holding pipe 41 ... First holding member 42 ... Second holding Member 43 ... Third holding member 44, 45 ... Insulating member

Claims (9)

A substantially cylindrical conductive anode;
An insulating tube made of quartz or machinable ceramic inserted inside the anode;
A rod-shaped cathode inserted inside the insulating tube so as not to contact the anode,
A plasma torch that forms plasma by applying a positive voltage and a negative voltage to the anode and the cathode, respectively. A ceramic plasma gas distributor is provided between the anode and the cathode in the vicinity of the tip of the cathode, positioning the relative position of the anode and the cathode, and uniformly distributing the plasma gas supplied to the cathode. The plasma torch according to claim 1. The cathode has, as an internal structure, a first hollow portion disposed in the center, a second hollow portion disposed on the outer periphery of the first hollow portion, and a third hollow disposed on the outer periphery of the second hollow portion. The plasma torch according to claim 1, wherein the plasma torch has a three-layer structure having a portion. The plasma torch according to claim 3, wherein the first hollow portion of the cathode is a plasma gas supply pipe. The second hollow portion of the cathode is an introduction pipe for a cooling medium;
The plasma torch according to claim 3, wherein the third hollow portion of the cathode is a discharge pipe for the cooling medium. The plasma torch according to claim 1, wherein the anode has a built-in cooling pipe. The plasma torch according to claim 1, wherein a VCR joint and / or an ICF flange is used as a vacuum seal. A method of forming a plasma by applying a positive voltage and a negative voltage to the anode and the cathode, respectively, and a method of forming a plasma by applying a positive voltage and a negative voltage to the object to be heated and the cathode, respectively. The plasma torch according to claim 1, which can be switched or used together. A substantially cylindrical conductive anode;
An insulating tube made of quartz or machinable ceramic inserted inside the anode;
A rod-like cathode inserted inside the insulating tube so as not to contact the anode;
A holding tube disposed on the outer periphery of the anode,
The holding tube is electrically connected to the cathode and mechanically holds the cathode, and the second holding member is electrically connected to the anode and mechanically holds the cathode. A third holding member that mechanically holds the anode and the cathode via the first holding member and the second holding member, and at least between the first holding member and the second holding member, and The second holding member and the third holding member are joined to a ceramic insulating member by welding, and the first holding member, the second holding member, and the third holding member are integrated while being insulated from each other. And
VCR joints and / or ICF flanges are used as vacuum seals for the anode, cathode and holding tube,
A plasma torch that forms plasma by applying a positive voltage and a negative voltage to the plasma chip and the internal electrode, respectively.

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