WO2007017977A1 - High-frequency induction thermal plasma torch and method for synthesizing solid material - Google Patents

High-frequency induction thermal plasma torch and method for synthesizing solid material Download PDF

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Publication number
WO2007017977A1
WO2007017977A1 PCT/JP2006/309427 JP2006309427W WO2007017977A1 WO 2007017977 A1 WO2007017977 A1 WO 2007017977A1 JP 2006309427 W JP2006309427 W JP 2006309427W WO 2007017977 A1 WO2007017977 A1 WO 2007017977A1
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Prior art keywords
pipe
tube
gas
plasma torch
raw material
Prior art date
Application number
PCT/JP2006/309427
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French (fr)
Japanese (ja)
Inventor
Tetsuya Otosaka
Yuuji Tobisaka
Original Assignee
Shin-Etsu Chemical Co., Ltd.
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Publication date
Application filed by Shin-Etsu Chemical Co., Ltd. filed Critical Shin-Etsu Chemical Co., Ltd.
Publication of WO2007017977A1 publication Critical patent/WO2007017977A1/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
    • C03B37/01815—Reactant deposition burners or deposition heating means
    • C03B37/01823—Plasma deposition burners or heating means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/085—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy creating magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0869—Feeding or evacuating the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0871—Heating or cooling of the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0881—Two or more materials
    • B01J2219/0883—Gas-gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/12—Processes employing electromagnetic waves
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/04—Multi-nested ports
    • C03B2207/08—Recessed or protruding ports
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/20—Specific substances in specified ports, e.g. all gas flows specified
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/20—Specific substances in specified ports, e.g. all gas flows specified
    • C03B2207/26—Multiple ports for glass precursor
    • C03B2207/28—Multiple ports for glass precursor for different glass precursors, reactants or modifiers
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/42—Assembly details; Material or dimensions of burner; Manifolds or supports
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

  • the present invention relates to a high frequency induction thermal plasma torch and a method for synthesizing a solid substance. More specifically, the present invention relates to a synthesis method for synthesizing a solid material such as an optical fiber glass base material from a raw material gas and an auxiliary raw material gas, and a high-frequency induction thermal plasma torch (hereinafter simply referred to as “plasma torch”) used therefor. .
  • a synthesis method for synthesizing a solid material such as an optical fiber glass base material from a raw material gas and an auxiliary raw material gas
  • plasma torch high-frequency induction thermal plasma torch
  • a high-frequency coil is arranged around a gas flow path tube, a high-frequency current is passed, and an internal gas is turned into plasma and injected. Moreover, it can be used as an ultra-high temperature reaction field because it can obtain an ultra-high temperature of about 10,000 degrees and a relatively slow plasma linear velocity and can freely select an oxidizing / reducing atmosphere.
  • the plasma torch can be preferably used for the synthesis of high-purity solid substances such as crystals, amorphous powders and the like.
  • it can be used as an ultra-high temperature heat source for volume reduction of waste and decomposition of CFCs.
  • ICP emission analysis because it can completely decompose the object at ultra-high temperatures.
  • FIG. 1 is a cross-sectional view schematically showing the structure of a plasma torch 100 used for the synthesis of fine particles or films of solid substances.
  • the plasma torch 100 includes a source gas supply pipe 2, an inner pipe 3, and an outer pipe 6 in order from the center. Inside the source gas supply pipe 2 is formed a source gas channel 1 through which the source gas mixed with the inert carrier gas flows, and the source gas flows from the source inlet formed at the rear end on the right side in the figure. The tip force that is introduced and moves to the left in the figure is also injected. Also, source gas supply pipe 2 and inner pipe 3 In between, a plasma gas flow path 4 through which a plasma gas flows is formed.
  • the source gas supply pipe 2 has a tip that is shorter than the inner pipe 3 and the outer pipe 6 and is retracted from the tips of the inner pipe 3 and the outer pipe 6. Further, between the inner pipe 3 and the outer pipe 6, a cooling water flow path 7 through which cooling water flows is formed. Further, a high frequency coil 8 is disposed outside the outer pipe 6 on the tip side where the source gas supply pipe 2 does not exist. Although not shown, since the source gas supply pipe 2 is also directly exposed to the high temperature plasma, a cooling water passage is also formed inside the source gas supply pipe 2 and is forcibly cooled.
  • Patent Document 1 describes a method for igniting the plasma torch 100 as described above.
  • a high-frequency current is supplied to the high-frequency coil while argon gas is supplied inside the plasma torch.
  • plasma 9 is generated inside the plasma torch 100 by applying a high voltage by means of a high voltage applying means (not shown) and discharging it.
  • the plasma 9 is injected toward the target rod 10.
  • the plasma 9 generated in the plasma torch 100 can be maintained, for example, by flowing a high-frequency current having a frequency of 1 to 4 MHz and a power of 20 to about LOO kVA through the high-frequency coil 8.
  • the outer pipe 6 is cooled by circulating cooling water through the cooling water flow path 7.
  • the plasma torch 100 as described above can be used, for example, for the synthesis of fluorine-doped quartz glass fine particles. That is, oxygen gas and argon gas are allowed to flow through the plasma gas channel 4, while a mixed gas of argon gas and source gas as an inert carrier gas is introduced into the source gas channel 1.
  • the source gas include fluorine-containing gases such as tetrasalt silicate, tetrafluoride, and carbon tetrafluoride.
  • fluorine-containing gases such as tetrasalt silicate, tetrafluoride, and carbon tetrafluoride.
  • fine particles of fluorine-doped quartz glass are synthesized inside the plasma 9.
  • the synthesized glass particles can be deposited on a target rod 10 made of pure quartz glass that rotates and moves, and can be used as a glass preform for an optical fiber formed of fluorine-doped quartz glass.
  • Patent Document 2 describes a structure of a plasma torch.
  • the plasma torch described here has a structure of a plasma torch having a plurality of tubes 11, 12, 2 of different lengths surrounding the tip of a medium nozzle 7 for supplying a raw material gas, It is stated that the deposition efficiency is improved by making the tip of the media nozzle 7 narrowed. It is.
  • Patent Document 1 Japanese Patent Laid-Open No. 05-242995
  • Patent Document 2 Japanese Translation of Special Publication 2005-532247
  • the present invention suppresses the solid material force synthesized using the plasma torch 100 from adhering to the plasma torch 100 itself, and makes the solid material efficient even for a relatively thin target rod 10.
  • the purpose is to provide a structure of a plasma torch 100 that can be deposited well and a method for synthesizing a solid substance using the plasma torch 100!
  • a first pipe that is supplied with a raw material gas and a mixed raw material gas of a carrier gas that is inert to the raw material gas and discharges the mixed raw material gas from the leading end.
  • the second tube Surrounding the first tube, the second tube that is supplied with an inert gas from the rear end and discharges the tip force inert gas between the outer surface of the first tube and the second tube.
  • a third raw material gas that is formed between the outer surface of the second pipe and is diluted with an inert gas from the rear end of the second pipe and that discharges the front force gas.
  • a quadruple pipe structure including a fourth pipe through which a cooling medium flows between the outer surface of the third pipe and synthesize a solid substance from the discharged mixed raw material gas and auxiliary raw material gas
  • a high-frequency induction thermal plasma torch which is disposed outside the fourth tube near the tip.
  • a high frequency induction thermal plasma torch in which the tips of the first tube and the second tube are retracted to the rear end side of the section where the high frequency coil is disposed in the fourth tube is provided. This suppresses the generation of eddy currents inside the plasma torch and prevents the solid substance synthesized in the plasma from adhering to the end face of the source gas supply pipe.
  • the gas is rectified, so that the diffusion of the synthesized solid substance fine particles is suppressed, and the solid substance fine particles are also prevented from adhering to the inner surface of the inner tube.
  • At least one of the first tube, the second tube, and the third tube is formed of a material containing silicon nitride or aluminum nitride.
  • the first tube and the second tube are supported by a block formed of an alloy having heat resistance and acid resistance, and the block is water-cooled. Is done. This prevents damage to the plasma torch caused by thermal radiation from the plasma.
  • a first pipe that is supplied with a source gas and a mixed source gas of a carrier gas that is inactive with respect to the source gas and discharges the source material gas from the tip is used as the rear end force.
  • a second pipe that is disposed so as to surround the first pipe is supplied with inert gas from the rear end, and discharges inert gas from the front end between the second pipe and the second pipe.
  • the coil further includes a tip of the first tube and the second tube, from the section where the high frequency coil is arranged in the fourth tube.
  • the first tube, the second tube, and the second tube are identical to the first tube, the second tube, and the second tube.
  • At least one of the three tubes is formed of a material containing silicon nitride or aluminum nitride.
  • the first tube and the second tube are supported by a block formed of an alloy having heat resistance and acid resistance, and the block is water-cooled. .
  • the block is water-cooled.
  • the source gas contains a silicon compound and the auxiliary source gas contains oxygen.
  • a high purity silicon compound can be synthesized using a plasma torch.
  • the key compound includes tetrasalt key. This makes it possible to synthesize a high-purity silicon compound using a plasma torch.
  • the solid substance is quartz glass.
  • quartz glass with high purity can be synthesized using a plasma torch.
  • the solid substance is quartz glass doped with impurities.
  • an impurity-added quartz glass obtained by adding a desired impurity to a high-purity quartz glass can be synthesized using a plasma torch.
  • the impurity includes fluorine.
  • a base material for a fluorine-doped optical fiber can be synthesized using a plasma torch.
  • the solid substance is a glass preform for optical fiber. This makes it possible to synthesize a high-quality glass preform for an optical fiber using a plasma torch.
  • the plasma torch having the structure as described above is a synthesized solid material even when the diameter of the target rod for depositing and depositing the synthesized solid material is considerably smaller than the diameter of the plasma torch. Can greatly increase the adhesion efficiency, and contribute to the improvement of productivity.
  • the final product is an optical fiber glass base material, there is little solid material adhering to the plasma torch! /, So there are very few bubbles! / And the base material is obtained.
  • FIG. 1 is a longitudinal sectional view schematically showing the structure of a plasma torch 100 that has been used for the synthesis of a solid substance.
  • FIG. 2 is a diagram showing an aspect of a gas flow 12 inside the plasma torch 100 shown in FIG.
  • FIG. 3 is a longitudinal sectional view schematically showing the structure of a plasma torch 200 according to one embodiment.
  • FIG. 4 is a diagram showing an aspect of a gas flow 22 inside the plasma torch 200 shown in FIG. 3.
  • FIG. 5 is a graph showing comparison of the adhesion efficiency of glass particles to target rods 10 and 24 having different diameters.
  • FIG. 2 is a diagram schematically showing an aspect of the gas flow 12 inside the plasma torch 100 shown in FIG.
  • the gas flow 12 of each gas discharged from the source gas flow channel 1 and the plasma gas flow channel 4 tries to go straight.
  • a vortex 11 is created inside the plasma torch 100 as dragged by these gas streams 12.
  • Part of the solid material fine particles synthesized inside the plasma 9 is transported in the direction opposite to the gas flow 12 by the vortex 11 and is deposited on the end face 5 facing the plasma 9 of the source gas supply pipe 2. .
  • the gas flowing through the plasma gas flow path 4 If the amount is small, the eddy current 11 generates solid material fine particles circulating inside the plasma torch 100, and some of them adhere to the inner surface of the inner tube 3.
  • the gas flow 12 that is also injected to the outside of the tip side force of the plasma torch 100 is diffused, and the flow of the solid substance fine particles is changed to the diameter of the raw material gas channel 1. It will be much thicker than. Therefore, it has been found that when the target rod 10 to which the solid fine particles are adhered is thin, the adhesion efficiency is lowered.
  • FIG. 3 is a cross-sectional view schematically showing the structure of the plasma torch 200 according to one embodiment.
  • the outer fourth tube 16 and the inner third tube 15 correspond to the outer tube 6 and the inner tube 3 in the plasma 100 shown in FIG.
  • a cooling water channel 20 through which cooling water flows is formed in the same manner as the plasma torch 100.
  • a double pipe structure including a first pipe 13 and a second pipe 14 is formed inside the third pipe 15. Therefore, the plasma torch 200 as a whole has a quadruple tube structure.
  • a source gas channel 17 into which a mixed gas of an inert carrier gas and a source gas is introduced is formed inside the first tube 13.
  • an inert gas flow path 18 through which an inert gas flows is formed between the outer surface of the first tube 13 and the inner surface of the second tube 14 surrounding the first tube 13.
  • an auxiliary material gas flow path for distributing an auxiliary material gas diluted with an inert gas as necessary between the outer surface of the second tube 14 and the inner surface of the third tube 15 surrounding the second tube 14. 19 is formed.
  • the first pipe 13 and the second pipe 14 have their leading ends retracted from the third pipe 15 and the fourth pipe 16, and in the section where the first pipe 13 and the second pipe 14 do not exist.
  • a high frequency coil 21 is disposed outside the fourth tube 16.
  • an inert gas is discharged from the inert gas flow path 18 between the first pipe 13 and the second pipe 14. It is. Therefore, the contact between the source gas discharged from the source gas channel 17 in the first pipe 13 and the auxiliary source gas channel 19 discharged from the sub-source gas channel 19 between the second pipe 14 and the third pipe 15 occurs. Be late. As a result, the solid material is synthesized at positions where the tip surface forces of the first tube 13 and the second tube 14 are separated from each other. From this point, the adhesion of the solid material to the first tube 13 and the second tube 14 is suppressed. Be controlled.
  • the fine particles conveyed to the gas flow 22 also flow while maintaining a diameter close to the diameter of the raw material gas flow path 17. This prevents the fine particles from adhering to the inside of the third tube 15 and further reduces the decrease in the adhesion efficiency even when the target rod 24 to which the fine particles are to be adhered is thin.
  • the high-frequency coil 21 is disposed in an area where the first tube 13 and the second tube 14 are present, which is in contact with the generated plasma 23. This is to prevent the first tube 13 and the second tube 14 from being damaged.
  • the first tube 13, the second tube 14 and the third tube 15 are preferably formed of a material having high heat resistance. Specifically, silicon nitride, boron nitride, silicon carbide, aluminum oxide, quartz glass, etc. can be exemplified, and further, nitride nitride excellent in heat resistance, acid resistance and thermal shock resistance is preferably exemplified. The force that can be produced is not limited to these materials. By using such a material, it is possible to almost completely prevent cracking and wear during operation of the plasma torch 200.
  • the first tube 13 and the second tube 14 are held by a metal block (not shown).
  • This metal block preferably has a water cooling structure in order to prevent damage due to radiant heat that reaches directly from the plasma.
  • the material is preferably an alloy having both heat resistance and acid resistance.
  • the force that can exemplify stainless steel (SUS316, etc.), nickel alloy (Inconel C-276, Incoloy G-3, etc.) is not limited to these.
  • FIG. 4 is a diagram schematically showing a layout of an apparatus when a solid material is synthesized using the plasma torch 200 having the structure shown in FIG.
  • plasma toe By spraying the plasma 23 generated by the gas 200 toward the surface of the target rod 24, solid substance fine particles synthesized in the plasma 24 can be deposited on the target rod 24. Therefore, a glass rod for optical fiber was manufactured by depositing glass fine particles of fluorine-doped quartz glass using a target rod 24 made of high-purity synthetic quartz glass.
  • the plasma torch 200 includes a first tube 13 having an inner diameter of 3 mm and an outer diameter of 8 mm formed from nitride nitride, and a second tube 14 having an inner diameter of 19 mm and an outer diameter of 24 mm formed from nitride nitride. And a third tube 15 having an inner diameter of 42 mm formed of nitride nitride.
  • the raw material gas flow path 17 formed inside the first pipe 13 is supplied with a mixed gas of 4. OLZmin argon gas, 2.0 LZmin tetrachloride gas and 0.76 LZmin tetrafluoride gas. The raw material gas was supplied.
  • target rods 24 Five types of high-purity synthetic quartz glass rods having outer diameters of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm were prepared as target rods 24.
  • the high-frequency coil 21 was supplied with a high-frequency current having a frequency of 3.5 MHz.
  • the power supply was adjusted so that the target rod 24 did not soften and the adhering glass particles became well transparent.
  • the target rod 24 was rotated and displaced in the longitudinal direction.
  • the rotation speed of the target rod 24 was 60 rpm
  • the moving speed in the longitudinal direction was 75 mmZmin
  • the moving range was 500 mm.
  • the glass particles were deposited until the outer diameter of the glass particles adhering to the target rod 24 was 1.1 times the diameter of the original target rod 24. Table 1 shows the adhesion efficiency of the five types of samples thus obtained.
  • the plasma torch 100 is formed by using a raw material gas supply pipe 2 having an inner diameter of 3 mm and an outer diameter of 38 mm made of nitride nitride, and an inner pipe 3 having an inner diameter of 42 mm made of nitride nitride. did.
  • OLZmin of tetrachlorosilane gas and 0.76 LZmin of tetrafluorocarbon gas was supplied to the raw material gas flow path 1 of the raw material gas supply pipe 2.
  • a plasma gas flow path 4 formed between the source gas supply pipe 2 and the inner pipe 3 was supplied with a mixed gas of 75 LZmin argon gas and 40 LZmin oxygen gas.
  • the high-frequency coil 8 was supplied with a high-frequency current having a frequency of 3.5 MHz.
  • the power supply was adjusted so that the target rod 10 did not soften and the adhering glass particles became well transparent.
  • the target rod 10 was rotated and displaced in the longitudinal direction. Tar
  • the rotation speed of the get bar 10 was 60 rpm
  • the moving speed in the longitudinal direction was 75 mmZmin
  • the moving range was 500 mm.
  • the glass particles were deposited until the outer diameter of the glass particles adhering to the target rod 10 became 1.1 times the outer diameter of the original target rod 10. Table 2 shows the adhesion efficiency of the five types of samples thus obtained.
  • FIG. 5 is a graph showing the relationship between the adhesion efficiency and the target diameter in Examples and Comparative Examples. As shown in the figure, by using the plasma torch 200 having the structure shown in FIG. 3, the adhesion efficiency is improved 2 to 5 times. Further, considering the time required for the cleaning work of the plasma torch 200, the difference in work efficiency between the plasma torch 100 and the plasma torch 200 is further increased.
  • the synthesis of high-quality solid materials that make the most of the characteristics of plasma torches can be performed stably over a long period of time. Therefore, for example, it contributes to the productivity improvement of the glass preform for optical fibers.

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Abstract

This invention provides a high-frequency induction thermal plasma torch (200) having a quadruple pipe structure comprising a first pipe (13) for delivering a mixed raw material gas from its front end, a second pipe (14), which is disposed so as to surround the first pipe (13) for delivering an inert gas from its front end, a third pipe (15), which is provided so as to surround the second pipe (14) for delivering an auxiliary raw material gas from its front end, and a fourth pipe (16), which is provided on the outer side of the third pipe (15) and through which a cooling medium is passed, whereby a solid material is synthesized from the delivered mixed raw material gas and the auxiliary raw material gas. In a part near the front end, a high-frequency coil (21) is further disposed on the outer side of the fourth pipe (16). The front end of the first pipe (13) and the second pipe (14) is located so as to retrograde on the back end side from a section in which, in the fourth pipe (16), the high-frequency coil (21) is disposed. In an internal gas stream (22), the occurrence of vortex flow is suppressed, and the synthesized solid material can be efficiently ejected.

Description

明 細 書  Specification
高周波誘導熱プラズマトーチおよび固体物質の合成方法  High frequency induction thermal plasma torch and method for synthesizing solid materials
技術分野  Technical field
[0001] 本発明は、高周波誘導熱プラズマトーチおよび固体物質の合成方法に関する。より 詳細には、原料ガスおよび副原料ガスから、光ファイバ用ガラス母材等の固体物質を 合成する合成方法と、それに用いる高周波誘導熱プラズマトーチ (以下、単に「ブラ ズマトーチ」と記載する）に関する。  The present invention relates to a high frequency induction thermal plasma torch and a method for synthesizing a solid substance. More specifically, the present invention relates to a synthesis method for synthesizing a solid material such as an optical fiber glass base material from a raw material gas and an auxiliary raw material gas, and a high-frequency induction thermal plasma torch (hereinafter simply referred to as “plasma torch”) used therefor. .
[0002] なお、文献の参照による組み込みが認められる指定国については、下記特許出願 の明細書に記載された内容を参照により本出願に組み込み、本件明細書の記載の 一部とする。  [0002] For designated countries where incorporation by reference of documents is permitted, the contents described in the specification of the following patent application are incorporated into the present application by reference and made a part of the description of the present specification.
特願 2005— 229520号 出願曰 2005年 8月 8曰  Japanese Patent Application No. 2005-229520 Application 曰 August 2005 曰
背景技術  Background art
[0003] プラズマトーチは、ガス流路管の周囲に高周波コイルを配置して高周波電流を流し 、内部のガスをプラズマ化して噴射する。また、 1万度程度の超高温を得ることができ ると共に、比較的遅いプラズマ線速が得られ、酸化 ·還元雰囲気を自由に選択できる ので、超高温の反応場として用いられる。  [0003] In a plasma torch, a high-frequency coil is arranged around a gas flow path tube, a high-frequency current is passed, and an internal gas is turned into plasma and injected. Moreover, it can be used as an ultra-high temperature reaction field because it can obtain an ultra-high temperature of about 10,000 degrees and a relatively slow plasma linear velocity and can freely select an oxidizing / reducing atmosphere.
[0004] プラズマトーチが発生するプラズマの反応場の内部には電極が存在しないので、 反応生成物に不純物が混入し難い。従って、プラズマトーチは、結晶、アモルファス 等の粉体'膜等、高純度固体物質の合成に好ましく使用できる。また、超高温の熱源 として、廃棄物の減容処理、フロンの分解等にも利用できる。更に、超高温で対象物 を完全に分解できるので、 ICP発光分析等にも用いられる。  [0004] Since there is no electrode inside the plasma reaction field where the plasma torch is generated, it is difficult for impurities to be mixed into the reaction product. Therefore, the plasma torch can be preferably used for the synthesis of high-purity solid substances such as crystals, amorphous powders and the like. In addition, it can be used as an ultra-high temperature heat source for volume reduction of waste and decomposition of CFCs. Furthermore, it can be used for ICP emission analysis because it can completely decompose the object at ultra-high temperatures.
[0005] 図 1は、固体物質の微粒子あるいは膜の合成に用いられているプラズマトーチ 100 の構造を模式的に示す断面図である。同図に示すように、プラズマトーチ 100は、中 心にから順に、原料ガス供給管 2、内側管 3および外側管 6を備える。原料ガス供給 管 2の内部には、不活性キャリアガスと混合された原料ガスが流れる原料ガス流路 1 が形成され、図上で右側になる後端に形成された原料導入口から原料ガスが導入さ れ、図上で左側になる先端力も噴射される。また、原料ガス供給管 2および内側管 3 の間には、プラズマガスを流すプラズマガス流路 4が形成される。 FIG. 1 is a cross-sectional view schematically showing the structure of a plasma torch 100 used for the synthesis of fine particles or films of solid substances. As shown in the figure, the plasma torch 100 includes a source gas supply pipe 2, an inner pipe 3, and an outer pipe 6 in order from the center. Inside the source gas supply pipe 2 is formed a source gas channel 1 through which the source gas mixed with the inert carrier gas flows, and the source gas flows from the source inlet formed at the rear end on the right side in the figure. The tip force that is introduced and moves to the left in the figure is also injected. Also, source gas supply pipe 2 and inner pipe 3 In between, a plasma gas flow path 4 through which a plasma gas flows is formed.
[0006] 原料ガス供給管 2は内側管 3および外側管 6よりも短ぐその先端は、内側管 3およ び外側管 6の先端よりも後退している。また、内側管 3および外側管 6の間には、冷却 水を流通させる冷却水流路 7が形成される。更に、原料ガス供給管 2が存在していな い先端側において、外側管 6の外側には高周波コイル 8が配置される。なお、図示は 省略したが、原料ガス供給管 2も高温のプラズマに直接に曝されるので、原料ガス供 給管 2の内部にも冷却水路が形成され、強制的に冷却される。 [0006] The source gas supply pipe 2 has a tip that is shorter than the inner pipe 3 and the outer pipe 6 and is retracted from the tips of the inner pipe 3 and the outer pipe 6. Further, between the inner pipe 3 and the outer pipe 6, a cooling water flow path 7 through which cooling water flows is formed. Further, a high frequency coil 8 is disposed outside the outer pipe 6 on the tip side where the source gas supply pipe 2 does not exist. Although not shown, since the source gas supply pipe 2 is also directly exposed to the high temperature plasma, a cooling water passage is also formed inside the source gas supply pipe 2 and is forcibly cooled.
[0007] 特許文献 1には、上記のようなプラズマトーチ 100の点火方法が記載されている。 [0007] Patent Document 1 describes a method for igniting the plasma torch 100 as described above.
即ち、プラズマトーチ 100を点火する場合は、まず、冷却水流路 7の冷却水を除いた 状態で、プラズマトーチ内部にアルゴンガスを流しつつ、高周波コイルに高周波電流 を流す。更に、図示していない高電圧印加手段により高電圧を印加して放電させるこ とによりプラズマトーチ 100の内部にプラズマ 9が発生する。プラズマ 9は、例えば、タ 一ゲット棒 10に向かって噴射される。なお、プラズマトーチ 100に発生したプラズマ 9 は、例えば、周波数 l〜4MHz、電力 20〜： LOO kVA程度の高周波電流を高周波 コイル 8に、流すことにより維持できる。また、プラズマトーチ 100が点火された後は、 冷却水流路 7に冷却水を流通させて外側管 6を冷却する。  That is, when the plasma torch 100 is ignited, first, with the cooling water in the cooling water flow path 7 removed, a high-frequency current is supplied to the high-frequency coil while argon gas is supplied inside the plasma torch. Furthermore, plasma 9 is generated inside the plasma torch 100 by applying a high voltage by means of a high voltage applying means (not shown) and discharging it. For example, the plasma 9 is injected toward the target rod 10. The plasma 9 generated in the plasma torch 100 can be maintained, for example, by flowing a high-frequency current having a frequency of 1 to 4 MHz and a power of 20 to about LOO kVA through the high-frequency coil 8. In addition, after the plasma torch 100 is ignited, the outer pipe 6 is cooled by circulating cooling water through the cooling water flow path 7.
[0008] 上記のようなプラズマトーチ 100は、例えば、フッ素ドープ石英ガラス微粒子の合成 に用いることができる。即ち、プラズマガス流路 4に酸素ガスおよびアルゴンガスを流 す一方、原料ガス流路 1に不活性キャリアガスとしてのアルゴンガスおよび原料ガス の混合ガスを導入する。原料ガスとしては、四塩ィ匕ケィ素、四フッ化ケィ素あるいは四 フッ化炭素等のフッ素含有ガスを例示できる。これにより、プラズマ 9の内部で、フッ素 ドープ石英ガラスの微粒子が合成される。合成されたガラス微粒子は、回転'移動す る純粋石英ガラス製のターゲット棒 10上に堆積させて、フッ素ドープ石英ガラスにより 形成された光ファイバ用ガラス母材とすることができる。 [0008] The plasma torch 100 as described above can be used, for example, for the synthesis of fluorine-doped quartz glass fine particles. That is, oxygen gas and argon gas are allowed to flow through the plasma gas channel 4, while a mixed gas of argon gas and source gas as an inert carrier gas is introduced into the source gas channel 1. Examples of the source gas include fluorine-containing gases such as tetrasalt silicate, tetrafluoride, and carbon tetrafluoride. As a result, fine particles of fluorine-doped quartz glass are synthesized inside the plasma 9. The synthesized glass particles can be deposited on a target rod 10 made of pure quartz glass that rotates and moves, and can be used as a glass preform for an optical fiber formed of fluorine-doped quartz glass.
[0009] また、特許文献 2には、プラズマトーチの構造に関する記載がある。ここに記載され たプラズマトーチは、原料ガスを供給する媒体ノズル 7の先端に対して、それを包囲 する互いに長さの異なる複数の管 11、 12、 2を有するプラズマトーチの構造を有し、 媒体ノズル 7の先端を絞った形状とすることにより堆積効率が向上される旨が記載さ れている。 [0009] Further, Patent Document 2 describes a structure of a plasma torch. The plasma torch described here has a structure of a plasma torch having a plurality of tubes 11, 12, 2 of different lengths surrounding the tip of a medium nozzle 7 for supplying a raw material gas, It is stated that the deposition efficiency is improved by making the tip of the media nozzle 7 narrowed. It is.
特許文献 1：特開平 05— 242995号公報  Patent Document 1: Japanese Patent Laid-Open No. 05-242995
特許文献 2：特表 2005 - 532247号公報  Patent Document 2: Japanese Translation of Special Publication 2005-532247
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0010] 上記のようなプラズマトーチ 100を用いて実際に固体物質を合成すると、プラズマ 9 内で合成された固体物質の微粒子の一部が、プラズマ 9に対面した原料ガス供給管 2の端面、内側管 3の内面等に付着して、固体物質の粉体または膜として成長する場 合がある。これらのプラズマトーチ内付着物は時間の経過とともに成長して剥がれ落 ち、プラズマの安定性を損ねる上、生成した粉体の粒度分布の広がりや膜の欠陥の 原因となる。また、ターゲット棒 10上に膜を成長させるような場合、生成した固体微粒 子の質量に対するターゲット棒 10上に付着する割合、すなわち付着効率が高々 40% と低ぐさらに、ターゲット棒が細い場合には付着効率がさらに低下するという問題が めつに。 [0010] When a solid substance is actually synthesized using the plasma torch 100 as described above, a part of the solid substance fine particles synthesized in the plasma 9 are end faces of the source gas supply pipe 2 facing the plasma 9, It may adhere to the inner surface of the inner tube 3 and grow as a solid substance powder or film. These deposits in the plasma torch grow and peel off over time, impairing the stability of the plasma, and causing the particle size distribution of the produced powder and film defects. In addition, when a film is grown on the target rod 10, the ratio of depositing on the target rod 10 relative to the mass of the generated solid particles, that is, the deposition efficiency is as low as 40%, and the target rod is thin. The problem is that the adhesion efficiency further decreases.
[0011] そこで、この発明は、プラズマトーチ 100を用いて合成した固体物質力 プラズマト ーチ 100自体に付着することを抑制し、且つ、比較的細いターゲット棒 10に対しても 固体物質を効率よく堆積できるプラズマトーチ 100の構造と、そのプラズマトーチ 100 を用いた固体物質の合成方法を提供することを目的として!/ヽる。  [0011] Therefore, the present invention suppresses the solid material force synthesized using the plasma torch 100 from adhering to the plasma torch 100 itself, and makes the solid material efficient even for a relatively thin target rod 10. The purpose is to provide a structure of a plasma torch 100 that can be deposited well and a method for synthesizing a solid substance using the plasma torch 100!
課題を解決するための手段  Means for solving the problem
[0012] 本発明の第 1の形態として、後端カゝら原料ガスおよび原料ガスに対して不活性なキ ャリアガスの混合原料ガスを供給され、先端から混合原料ガスを吐出する第 1管と、 第 1管を包囲して配置され、第 1管の外面との間において、後端から不活性ガスを供 給され、先端力 不活性ガスを吐出する第 2管と、第 2管を包囲して形成され、第 2管 の外面との間において、後端カゝら不活性ガスで希釈された副原料ガスを供給され、 先端力 副原料ガスを吐出する第 3管と、第 3管の外側に形成され、第 3管の外面と の間において、冷却媒体が流通する第 4管とを含む 4重管構造を有し、吐出した混合 原料ガスおよび副原料ガスから固体物質を合成する高周波誘導熱プラズマトーチで あって、先端の近傍において第 4管の外側に配置された高周波コイルを更に備え、 且つ、第 1管、第 2管の先端が、第 4管において高周波コイルが配置された区間よりも 後端側に後退している高周波誘導熱プラズマトーチが提供される。これにより、ブラ ズマトーチの内側における渦流の発生を抑制し、プラズマ内で合成された固体物質 が原料ガス供給管の先端端面等に付着することが防止される。また、ガスが整流され ることにより、合成された固体物質微粒子の拡散が抑制され、内側管の内面に固体 物質微粒子が付着することも抑制される。これらの作用により、合成された固体物質 の微粒子はプラズマトーチの外部に向力つて効率よく噴射され、ターゲットに付着す る。 [0012] As a first embodiment of the present invention, there is provided a first pipe that is supplied with a raw material gas and a mixed raw material gas of a carrier gas that is inert to the raw material gas and discharges the mixed raw material gas from the leading end. Surrounding the first tube, the second tube that is supplied with an inert gas from the rear end and discharges the tip force inert gas between the outer surface of the first tube and the second tube. A third raw material gas that is formed between the outer surface of the second pipe and is diluted with an inert gas from the rear end of the second pipe and that discharges the front force gas. And a quadruple pipe structure including a fourth pipe through which a cooling medium flows between the outer surface of the third pipe and synthesize a solid substance from the discharged mixed raw material gas and auxiliary raw material gas A high-frequency induction thermal plasma torch, which is disposed outside the fourth tube near the tip. Further equipped with In addition, a high frequency induction thermal plasma torch in which the tips of the first tube and the second tube are retracted to the rear end side of the section where the high frequency coil is disposed in the fourth tube is provided. This suppresses the generation of eddy currents inside the plasma torch and prevents the solid substance synthesized in the plasma from adhering to the end face of the source gas supply pipe. Moreover, the gas is rectified, so that the diffusion of the synthesized solid substance fine particles is suppressed, and the solid substance fine particles are also prevented from adhering to the inner surface of the inner tube. By these actions, the synthesized fine particles of solid material are efficiently ejected to the outside of the plasma torch and adhere to the target.
[0013] また、ひとつの実施形態によると、上記高周波プラズマトーチにおいて、第 1管、第 2管および第 3管の少なくともひとつは、窒化ケィ素または窒化アルミニウムを含む材 料で形成される。これにより、プラズマトーチ自体の耐熱性、耐酸性を向上させ、ブラ ズマトーチの長寿命化と固体物質の安定な合成が実現される。  [0013] According to one embodiment, in the high-frequency plasma torch, at least one of the first tube, the second tube, and the third tube is formed of a material containing silicon nitride or aluminum nitride. As a result, the heat resistance and acid resistance of the plasma torch itself are improved, the life of the plasma torch is extended, and the solid material is stably synthesized.
[0014] また、他の実施形態によると、上記高周波プラズマトーチにおいて、第 1管および第 2管は、耐熱性および耐酸性を有する合金で形成されたブロックにより支持され、且 つ、ブロックが水冷される。これにより、プラズマからの熱輻射に起因するプラズマトー チの損傷を防止できる。  [0014] According to another embodiment, in the high-frequency plasma torch, the first tube and the second tube are supported by a block formed of an alloy having heat resistance and acid resistance, and the block is water-cooled. Is done. This prevents damage to the plasma torch caused by thermal radiation from the plasma.
[0015] 更に、本発明の第 2の形態として、後端力も原料ガスおよび原料ガスに対して不活 性なキャリアガスの混合原料ガスを供給され、先端から混合原料ガスを吐出する第 1 管と、第 1管を包囲して配置され、第 1管の外面との間において、後端から不活性ガ スを供給され、先端から不活性ガスを吐出する第 2管と、第 2管を包囲して形成され、 第 2管の外面との間において、後端カゝら不活性ガスで希釈された副原料ガスを供給 され、先端力 副原料ガスを吐出する第 3管と、第 3管の外側に形成され、第 3管の 外面との間において、冷却媒体が流通する第 4管とを含む 4重管構造を有し、先端の 近傍において第 4管の外側に配置された高周波コイルを更に備え、且つ、第 1管、第 2管の先端が、第 4管において高周波コイルが配置された区間よりも後端側に後退し て ヽる高周波誘導熱プラズマトーチを用いて、吐出した混合原料ガスおよび副原料 ガスから固体物質を合成する固体物質の合成方法が提供される。これにより、プラズ マ内で合成された固体物質が効率良く噴射されるので、純度の高い固体物質を効率 よく合成できる。また、合成された固体物質微粒子が拡散しないので、細いターゲット に対しても固体物質微粒子を効率よく付着させることができる。 [0015] Further, as a second mode of the present invention, a first pipe that is supplied with a source gas and a mixed source gas of a carrier gas that is inactive with respect to the source gas and discharges the source material gas from the tip is used as the rear end force. And a second pipe that is disposed so as to surround the first pipe, is supplied with inert gas from the rear end, and discharges inert gas from the front end between the second pipe and the second pipe. A third pipe that is formed so as to surround and is supplied with a secondary raw material gas diluted with an inert gas from the rear end of the second pipe and discharges a leading force secondary raw material gas between the second pipe and the third pipe. A high-frequency tube formed on the outside of the tube and having a quadruple tube structure including a fourth tube through which a cooling medium flows between the outer surface of the third tube and disposed outside the fourth tube in the vicinity of the tip. The coil further includes a tip of the first tube and the second tube, from the section where the high frequency coil is arranged in the fourth tube. Using Ru high frequency induction thermal plasma torch to retract the rear end, the synthesis method of a solid substance to synthesize the solid material is provided from the ejected mixed material gas and the auxiliary raw material gas. As a result, the solid material synthesized in the plasma is injected efficiently, so that the solid material with high purity can be efficiently used. Can be synthesized well. Further, since the synthesized solid substance fine particles do not diffuse, the solid substance fine particles can be efficiently attached even to a thin target.
[0016] また、ひとつの実施形態によると、上記合成方法において、第 1管、第 2管および第 [0016] According to one embodiment, in the synthesis method, the first tube, the second tube, and the second tube
3管の少なくともひとつが、窒化ケィ素または窒化アルミニウムを含む材料で形成され る。これにより、プラズマトーチ自体の耐熱性、耐酸性が向上され、固体物質の合成 を長期間にわたって安定に継続できる。 At least one of the three tubes is formed of a material containing silicon nitride or aluminum nitride. As a result, the heat resistance and acid resistance of the plasma torch itself are improved, and the synthesis of the solid substance can be continued stably over a long period of time.
[0017] 更に、他の実施形態によると、上記合成方法において、第 1管および第 2管が、耐 熱性および耐酸性を有する合金で形成されたブロックにより支持され、且つ、ブロック が水冷される。これにより、プラズマからの熱輻射に起因するプラズマトーチの損傷を 防止でき、固体物質の合成を長期間にわたって継続できる。 [0017] Further, according to another embodiment, in the above synthesis method, the first tube and the second tube are supported by a block formed of an alloy having heat resistance and acid resistance, and the block is water-cooled. . As a result, damage to the plasma torch caused by thermal radiation from the plasma can be prevented, and the synthesis of the solid material can be continued for a long period of time.
[0018] また他の実施形態によると、上記合成方法において、原料ガスがケィ素化合物を含 み、副原料ガスが酸素を含む。これにより、プラズマトーチを利用して、純度の高いケ ィ素化合物を合成できる。 [0018] According to another embodiment, in the above synthesis method, the source gas contains a silicon compound and the auxiliary source gas contains oxygen. Thus, a high purity silicon compound can be synthesized using a plasma torch.
[0019] また他の実施形態によると、上記合成方法において、ケィ素化合物が四塩ィ匕ケィ 素を含む。これにより、プラズマトーチを利用して、純度の高いケィ素化合物を合成で きる。 [0019] According to another embodiment, in the above synthesis method, the key compound includes tetrasalt key. This makes it possible to synthesize a high-purity silicon compound using a plasma torch.
[0020] また他の実施形態によると、上記合成方法にお!、て、固体物質が、石英ガラスであ る。これにより、プラズマトーチを用いて、純度の高い石英ガラスを合成できる。  [0020] According to another embodiment, in the above synthesis method, the solid substance is quartz glass. Thereby, quartz glass with high purity can be synthesized using a plasma torch.
[0021] また他の実施形態によると、上記合成方法において、固体物質が、不純物をドープ された石英ガラスである。これにより、プラズマトーチを用いて、純度の高い石英ガラ スに所望の不純物を添加した不純物添加石英ガラスを合成できる。  [0021] According to another embodiment, in the above synthesis method, the solid substance is quartz glass doped with impurities. Thus, an impurity-added quartz glass obtained by adding a desired impurity to a high-purity quartz glass can be synthesized using a plasma torch.
[0022] また他の実施形態によると、上記合成方法において、不純物がフッ素を含む。これ により、プラズマトーチを用いて、フッ素添加光ファイバ用母材を合成できる。  [0022] According to another embodiment, in the synthesis method, the impurity includes fluorine. Thus, a base material for a fluorine-doped optical fiber can be synthesized using a plasma torch.
[0023] また他の実施形態によると、上記合成方法において、固体物質が、光ファイバ用ガ ラス母材である。これにより、プラズマトーチを用いて、高品質な光ファイバ用ガラス母 材を合成できる。  [0023] According to another embodiment, in the above synthesis method, the solid substance is a glass preform for optical fiber. This makes it possible to synthesize a high-quality glass preform for an optical fiber using a plasma torch.
[0024] ただし、上記の発明の概要は、本発明の必要な特徴の全てを列挙したものではな V、。これらの特徴群のサブコンビネーションもまた発明となり得る。 発明の効果 [0024] However, the above summary of the invention does not enumerate all the necessary features of the present invention. Sub-combinations of these feature groups can also be an invention. The invention's effect
[0025] 上記のような構造を有するプラズマトーチは、合成された固体物質を付着堆積させ るターゲット棒の径がプラズマトーチ径に比較してかなり細い場合であっても、合成さ れた固体物質の付着効率を大きく高めることができ、生産性の向上に寄与する。加え て、最終製品が光ファイバ用ガラス母材である場合、プラズマトーチ内に付着する固 体物質が少な!/、ので、極めて気泡の少な!/、母材が得られる。  [0025] The plasma torch having the structure as described above is a synthesized solid material even when the diameter of the target rod for depositing and depositing the synthesized solid material is considerably smaller than the diameter of the plasma torch. Can greatly increase the adhesion efficiency, and contribute to the improvement of productivity. In addition, when the final product is an optical fiber glass base material, there is little solid material adhering to the plasma torch! /, So there are very few bubbles! / And the base material is obtained.
図面の簡単な説明  Brief Description of Drawings
[0026] [図 1]固体物質の合成に使用されてきたプラズマトーチ 100の構造の模式的に示す 縦断面図である。  FIG. 1 is a longitudinal sectional view schematically showing the structure of a plasma torch 100 that has been used for the synthesis of a solid substance.
[図 2]図 1に示したプラズマトーチ 100の内部におけるガス流 12の態様を示す図であ る。  FIG. 2 is a diagram showing an aspect of a gas flow 12 inside the plasma torch 100 shown in FIG.
[図 3]ひとつの実施形態に係るプラズマトーチ 200の構造を模式的に示す縦断面図 である。  FIG. 3 is a longitudinal sectional view schematically showing the structure of a plasma torch 200 according to one embodiment.
[図 4]図 3に示したプラズマトーチ 200の内部におけるガス流 22の態様を示す図であ る。  FIG. 4 is a diagram showing an aspect of a gas flow 22 inside the plasma torch 200 shown in FIG. 3.
[図 5]径の異なるターゲット棒 10、 24に対するガラス微粒子の付着効率を比較して示 すグラフである。  FIG. 5 is a graph showing comparison of the adhesion efficiency of glass particles to target rods 10 and 24 having different diameters.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0027] 以下、発明の実施の形態を通じて本発明を説明する。ただし、以下の実施形態は 請求の範隨こかかる発明を限定するものではない。また、実施形態の中で説明され て 、る特徴の組み合わせの全てが発明の解決手段に必須であるとは限らな 、。  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the claimed invention. In addition, all the combinations of features described in the embodiments are not necessarily essential for the solution of the invention.
[0028] 図 2は、図 1に示したプラズマトーチ 100の内部におけるガス流 12の態様を模式的 に示す図である。同図に示すように、プラズマトーチ 100の内部において、原料ガス 流路 1およびプラズマガス流路 4から吐出された各ガスのガス流 12はそれぞれに直 進しょうとする。しかしながら、これらのガス流 12に引きずられるようにして、プラズマト ーチ 100の内部で渦流 11が生じる。プラズマ 9の内部で合成された固体物質微粒子 の一部は、この渦流 11により、ガス流 12と反対の方向に運ばれ、原料ガス供給管 2 のプラズマ 9側に面した端面 5上に堆積する。また、プラズマガス流路 4を流れるガス の量が少な!/、場合は、渦流 11によりプラズマトーチ 100の内部で循環する固体物質 微粒子が生じ、その一部は内側管 3の内面にも付着する。 FIG. 2 is a diagram schematically showing an aspect of the gas flow 12 inside the plasma torch 100 shown in FIG. As shown in the figure, inside the plasma torch 100, the gas flow 12 of each gas discharged from the source gas flow channel 1 and the plasma gas flow channel 4 tries to go straight. However, a vortex 11 is created inside the plasma torch 100 as dragged by these gas streams 12. Part of the solid material fine particles synthesized inside the plasma 9 is transported in the direction opposite to the gas flow 12 by the vortex 11 and is deposited on the end face 5 facing the plasma 9 of the source gas supply pipe 2. . The gas flowing through the plasma gas flow path 4 If the amount is small, the eddy current 11 generates solid material fine particles circulating inside the plasma torch 100, and some of them adhere to the inner surface of the inner tube 3.
[0029] 更に、上記のような渦流 11の影響により、プラズマトーチ 100の先端側力も外へ噴 射されるガス流 12が拡散して、固体物質微粒子の流れが、原料ガス流路 1の径よりも 遥かに太くなつてしまう。従って、固体微粒子を付着させるターゲット棒 10が細い場 合は、付着効率が低下することが判明した。  [0029] Further, due to the influence of the vortex 11 as described above, the gas flow 12 that is also injected to the outside of the tip side force of the plasma torch 100 is diffused, and the flow of the solid substance fine particles is changed to the diameter of the raw material gas channel 1. It will be much thicker than. Therefore, it has been found that when the target rod 10 to which the solid fine particles are adhered is thin, the adhesion efficiency is lowered.
[0030] 図 3は、ひとつの実施形態に係るプラズマトーチ 200の構造を模式的に示す断面 図である。同図に示すように、このプラズマトーチ 200において、外側の第 4管 16お よびその内側の第 3管 15は、図 1に示したプラズマ 100における外側管 6および内側 管 3に相当し、これらの間にはプラズマトーチ 100と同様に冷却水が流通する冷却水 路 20が形成される。一方、第 3管 15の内側には、第 1管 13および第 2管 14による二 重管構造が形成されている。従って、プラズマトーチ 200全体としては、 4重管構造が 形成されている。  FIG. 3 is a cross-sectional view schematically showing the structure of the plasma torch 200 according to one embodiment. As shown in the figure, in this plasma torch 200, the outer fourth tube 16 and the inner third tube 15 correspond to the outer tube 6 and the inner tube 3 in the plasma 100 shown in FIG. A cooling water channel 20 through which cooling water flows is formed in the same manner as the plasma torch 100. On the other hand, a double pipe structure including a first pipe 13 and a second pipe 14 is formed inside the third pipe 15. Therefore, the plasma torch 200 as a whole has a quadruple tube structure.
[0031] 即ち、プラズマトーチ 200の中心には、第 1管 13の内側に、不活 ¾キャリアガスおよ び原料ガスの混合ガスが導入される原料ガス流路 17が形成される。また、第 1管 13 の外面と、第 1管 13を包囲する第 2管 14の内面との間には、不活性ガスを流通させ る不活性ガス流路 18が形成される。更に、第 2管 14の外面と、第 2管 14を包囲する 第 3管 15の内面との間に、必要に応じて不活性ガスで希釈された副原料ガスを流通 させる副原料ガス流路 19が形成される。また、第 1管 13および第 2管 14は、その先 端側が、第 3管 15および第 4管 16よりも後退しており、第 1管 13および第 2管 14が存 在しない区間において、第 4管 16の外側に高周波コイル 21が配置されている。  That is, at the center of the plasma torch 200, a source gas channel 17 into which a mixed gas of an inert carrier gas and a source gas is introduced is formed inside the first tube 13. In addition, an inert gas flow path 18 through which an inert gas flows is formed between the outer surface of the first tube 13 and the inner surface of the second tube 14 surrounding the first tube 13. Further, an auxiliary material gas flow path for distributing an auxiliary material gas diluted with an inert gas as necessary between the outer surface of the second tube 14 and the inner surface of the third tube 15 surrounding the second tube 14. 19 is formed. Further, the first pipe 13 and the second pipe 14 have their leading ends retracted from the third pipe 15 and the fourth pipe 16, and in the section where the first pipe 13 and the second pipe 14 do not exist. A high frequency coil 21 is disposed outside the fourth tube 16.
[0032] 上記のように 4重管構造を有するプラズマトーチ 200の内部においては、その内部 の奥全面力 ガスが供給されるので、図中に矢印で示すように、一方向に流れるガス 流 22は全体に均一に形成される。従って、プラズマトーチ 200の内部における渦流 の発生を最小限に抑えることができる。これにより、プラズマ 23の内部で合成された 固体物質の微粒子も、ガス流 22の流れる方向に一様に流れ、第 1管 13および第 2管 14の先端側端面に付着することがない。  [0032] Inside the plasma torch 200 having a quadruple tube structure as described above, gas is supplied to the inner surface of the interior of the plasma torch 200, and as shown by the arrows in the figure, the gas flow flowing in one direction 22 Are uniformly formed throughout. Therefore, the generation of vortex inside the plasma torch 200 can be minimized. As a result, the fine particles of the solid substance synthesized inside the plasma 23 also flow uniformly in the direction in which the gas flow 22 flows, and do not adhere to the end faces of the first tube 13 and the second tube 14.
[0033] また、第 1管 13および第 2管 14の間に不活性ガス流路 18から不活性ガスが吐出さ れる。従って、第 1管 13内の原料ガス流路 17から吐出された原料ガスと、第 2管 14 および第 3管 15の間の副原料ガス流路 19から吐出される副原料ガスとの接触が遅 れる。これにより、第 1管 13および第 2管 14の先端面力 離れた位置で固体物質が 合成されるので、この点からも、第 1管 13および第 2管 14への固体物質の付着が抑 制される。 In addition, an inert gas is discharged from the inert gas flow path 18 between the first pipe 13 and the second pipe 14. It is. Therefore, the contact between the source gas discharged from the source gas channel 17 in the first pipe 13 and the auxiliary source gas channel 19 discharged from the sub-source gas channel 19 between the second pipe 14 and the third pipe 15 occurs. Be late. As a result, the solid material is synthesized at positions where the tip surface forces of the first tube 13 and the second tube 14 are separated from each other. From this point, the adhesion of the solid material to the first tube 13 and the second tube 14 is suppressed. Be controlled.
[0034] 更に、プラズマトーチ 200の内部で平行性が維持されるのでガス流 22の拡散が抑 制される。従って、ガス流 22に搬送される微粒子も、原料ガス流路 17の径に近い径 を維持したまま流れる。これにより、微粒子が第 3管 15の内側に付着することが防止 され、更に、微粒子を付着させるべきターゲット棒 24が細い場合においても付着効率 の低下が少ない。  [0034] Furthermore, since the parallelism is maintained inside the plasma torch 200, diffusion of the gas flow 22 is suppressed. Therefore, the fine particles conveyed to the gas flow 22 also flow while maintaining a diameter close to the diameter of the raw material gas flow path 17. This prevents the fine particles from adhering to the inside of the third tube 15 and further reduces the decrease in the adhesion efficiency even when the target rod 24 to which the fine particles are to be adhered is thin.
[0035] なお、上記のプラズマトーチ 200において、高周波コイル 21が、第 1管 13および第 2管 14の存在して ヽな 、領域に配置されて 、るのは、発生したプラズマ 23との接触 によって第 1管 13および第 2管 14が破損することを防止するためである。同様の観点 から、第 1管 13、第 2管 14および第 3管 15は高い耐熱性を有する材料により形成す ることが好ましい。具体的には、窒化ケィ素、窒化ホウ素、炭化ケィ素、酸化アルミ- ゥム、石英ガラス等を例示でき、更に、耐熱性 ·耐酸性 ·耐熱衝撃性に優れた窒化ケ ィ素を好ましく例示できる力 これらの材料に限定されるわけではない。このような材 料を用いることにより、プラズマトーチ 200の稼働中の割れや消耗をほぼ完全に防止 できる。  In the plasma torch 200 described above, the high-frequency coil 21 is disposed in an area where the first tube 13 and the second tube 14 are present, which is in contact with the generated plasma 23. This is to prevent the first tube 13 and the second tube 14 from being damaged. From the same viewpoint, the first tube 13, the second tube 14 and the third tube 15 are preferably formed of a material having high heat resistance. Specifically, silicon nitride, boron nitride, silicon carbide, aluminum oxide, quartz glass, etc. can be exemplified, and further, nitride nitride excellent in heat resistance, acid resistance and thermal shock resistance is preferably exemplified. The force that can be produced is not limited to these materials. By using such a material, it is possible to almost completely prevent cracking and wear during operation of the plasma torch 200.
[0036] また、上記のプラズマトーチ 200において、第 1管 13および第 2管 14は、図示して いない金属製ブロックにより保持される。この金属製ブロックは、プラズマから直接届 く輻射熱による損傷を防ぐために水冷構造とすることが好ましい。また、その材質は、 耐熱性と耐酸性を兼ね備えた合金が好ましい。具体的には、ステンレス（SUS316等 )、ニッケル合金 (インコネル C— 276、インコロイ G— 3等）等を例示できる力 これら に限定されるわけではない。  [0036] In the plasma torch 200, the first tube 13 and the second tube 14 are held by a metal block (not shown). This metal block preferably has a water cooling structure in order to prevent damage due to radiant heat that reaches directly from the plasma. The material is preferably an alloy having both heat resistance and acid resistance. Specifically, the force that can exemplify stainless steel (SUS316, etc.), nickel alloy (Inconel C-276, Incoloy G-3, etc.) is not limited to these.
実施例  Example
[0037] 図 4は、図 3に示した構造を有するプラズマトーチ 200を用いて固体物質を合成す る場合の装置のレイアウトを模式的に示す図である。同図に示すように、プラズマトー チ 200が発生するプラズマ 23をターゲット棒 24の表面に向かって噴射させることによ り、プラズマ 24内で合成された固体物質微粒子をターゲット棒 24に堆積させることが できる。そこで、高純度合成石英ガラス製のターゲット棒 24を用い、フッ素ドープ石英 ガラスのガラス微粒子を堆積させて、光ファイバ用ガラス母材を製造した。 FIG. 4 is a diagram schematically showing a layout of an apparatus when a solid material is synthesized using the plasma torch 200 having the structure shown in FIG. As shown in the figure, plasma toe By spraying the plasma 23 generated by the gas 200 toward the surface of the target rod 24, solid substance fine particles synthesized in the plasma 24 can be deposited on the target rod 24. Therefore, a glass rod for optical fiber was manufactured by depositing glass fine particles of fluorine-doped quartz glass using a target rod 24 made of high-purity synthetic quartz glass.
[0038] プラズマトーチ 200は、窒化ケィ素により形成された内径 φ 3mm、外径 φ 8mmの 第 1管 13と、窒化ケィ素により形成された内径 φ 19mm、外径 φ 24mmの第 2管 14 と、窒化ケィ素により形成された内径 φ 42mmの第 3管 15とを用いて形成した。第 1 管 13の内部に形成された原料ガス流路 17には、 4. OLZminのアルゴンガス、 2. 0 LZminの四塩化ケィ素ガスおよび 0. 76LZminの四フッ化ケィ素ガスの混合ガス を原料ガスとして供給した。また、第 1管 13および第 2管 14の間に形成された不活性 ガス流路 18には、 20L/minのアルゴンガスを供給した。更に、第 2管 14および第 3 管 15の間に形成された副原料ガス流路 19には、 30LZminのアルゴンガスと 40LZ minの酸素ガスとの混合ガスを供給した。  [0038] The plasma torch 200 includes a first tube 13 having an inner diameter of 3 mm and an outer diameter of 8 mm formed from nitride nitride, and a second tube 14 having an inner diameter of 19 mm and an outer diameter of 24 mm formed from nitride nitride. And a third tube 15 having an inner diameter of 42 mm formed of nitride nitride. The raw material gas flow path 17 formed inside the first pipe 13 is supplied with a mixed gas of 4. OLZmin argon gas, 2.0 LZmin tetrachloride gas and 0.76 LZmin tetrafluoride gas. The raw material gas was supplied. Further, 20 L / min of argon gas was supplied to an inert gas flow path 18 formed between the first pipe 13 and the second pipe 14. Further, a mixed gas of 30 LZmin argon gas and 40 LZ min oxygen gas was supplied to the auxiliary material gas flow path 19 formed between the second pipe 14 and the third pipe 15.
[0039] 一方、ターゲット棒 24として、 20mm、 30mm, 40mm, 50mm, 60mmの外径を 有する 5種類の高純度合成石英ガラス棒を用意した。また、高周波コイル 21には周 波数 3. 5MHzの高周波電流を供給した。供給電力は、ターゲット棒 24が軟ィ匕せず、 且つ、付着したガラス微粒子が良好に透明化するように調整した。また、ガラス微粒 子を堆積させる間は、ターゲット棒 24を回転させ、且つ、長手方向に変位させた。タ 一ゲット棒 24の回転数は 60rpm、長手方向に移動速度は 75mmZmin、移動範囲 は 500mmとした。ガラス微粒子の堆積は、ターゲット棒 24に付着したガラス微粒子 の外径が、元のターゲット棒 24の径の 1. 1倍になるまで行った。こうして得られた 5種 類の試料につ 、て、それぞれの付着効率を表 1に併せて示す。  On the other hand, five types of high-purity synthetic quartz glass rods having outer diameters of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm were prepared as target rods 24. The high-frequency coil 21 was supplied with a high-frequency current having a frequency of 3.5 MHz. The power supply was adjusted so that the target rod 24 did not soften and the adhering glass particles became well transparent. During the deposition of the glass particles, the target rod 24 was rotated and displaced in the longitudinal direction. The rotation speed of the target rod 24 was 60 rpm, the moving speed in the longitudinal direction was 75 mmZmin, and the moving range was 500 mm. The glass particles were deposited until the outer diameter of the glass particles adhering to the target rod 24 was 1.1 times the diameter of the original target rod 24. Table 1 shows the adhesion efficiency of the five types of samples thus obtained.
[0040] [表 1] ターゲッ ト径 入力パワー 付着効率 [0040] [Table 1] Target diameter Input power Adhesion efficiency
[mmj [kVA] [ 3  [mmj [kVA] [3
60 63 74  60 63 74
50 61 72  50 61 72
40 57 68  40 57 68
30 51 62  30 51 62
20 40 50  20 40 50
[0041] 表 1に示す通り、外径が 20mm φという細径のターゲット棒 24に対しても、 50%とい う高い付着効率が達成されていた。また、ガラス微粒子の堆積が終了した後のプラズ マトーチ 200を検査したところ、内部にガラス微粒子の付着はなぐ清浄な状態が保 たれていた。 [0041] As shown in Table 1, a high adhesion efficiency of 50% was achieved even for the target rod 24 having a small outer diameter of 20 mmφ. Further, when the plasma torch 200 after the deposition of the fine glass particles was inspected, it was found that the inside of the plasma torch 200 was kept clean and free from the adhesion of the fine glass particles.
[0042] (比較例）  [0042] (Comparative example)
図 1に示した構造を有するプラズマトーチ 100を用い、実施例と同じ条件で回転'往 復する高純度合成石英ガラス製のターゲット棒 10上に、フッ素ドープ石英ガラスのガ ラス微粒子を堆積させて光ファイバ用ガラス母材を作製した。  Using a plasma torch 100 having the structure shown in FIG. 1, glass fine particles of fluorine-doped quartz glass are deposited on a target rod 10 made of high-purity synthetic quartz glass that rotates and moves back and forth under the same conditions as in the example. An optical fiber glass preform was produced.
[0043] プラズマトーチ 100は、窒化ケィ素により形成された内径 φ 3mm、外径 φ 38mmの 原料ガス供給管 2と、窒化ケィ素により形成された内径 φ 42mmの内側管 3とを用い て形成した。また、原料ガス供給管 2の原料ガス流路 1には 4LZminのアルゴンガス 、 2. OLZminの四塩化ケィ素ガスおよび 0. 76LZminの四フッ化ケィ素ガスの混 合ガスを供給した。また、原料ガス供給管 2および内側管 3の間に形成されたプラズ マガス流路 4には、 75LZminのアルゴンガスと 40LZminの酸素ガスとの混合ガス を供給した。  [0043] The plasma torch 100 is formed by using a raw material gas supply pipe 2 having an inner diameter of 3 mm and an outer diameter of 38 mm made of nitride nitride, and an inner pipe 3 having an inner diameter of 42 mm made of nitride nitride. did. In addition, a mixed gas of 4 LZmin of argon gas, 2. OLZmin of tetrachlorosilane gas and 0.76 LZmin of tetrafluorocarbon gas was supplied to the raw material gas flow path 1 of the raw material gas supply pipe 2. A plasma gas flow path 4 formed between the source gas supply pipe 2 and the inner pipe 3 was supplied with a mixed gas of 75 LZmin argon gas and 40 LZmin oxygen gas.
[0044] 一方、ターゲット棒 10として、 20mm、 30mm, 40mm, 50mm, 60mmの外径を 有する 5種類の高純度合成石英ガラス棒を用意した。また、高周波コイル 8には周波 数 3. 5MHzの高周波電流を供給した。供給電力は、ターゲット棒 10が軟ィ匕せず、且 つ、付着したガラス微粒子が良好に透明化するように調整した。また、ガラス微粒子 を堆積させる間は、ターゲット棒 10を回転させ、且つ、長手方向に変位させた。ター ゲット棒 10の回転数は 60rpm、長手方向に移動速度は 75mmZmin、移動範囲は 500mmとした。ガラス微粒子の堆積は、ターゲット棒 10に付着したガラス微粒子の 外径が、元のターゲット棒 10の外径の 1. 1倍になるまで行った。こうして得られた 5種 類の試料について、それぞれの付着効率を表 2に示す。 On the other hand, five types of high-purity synthetic quartz glass rods having outer diameters of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm were prepared as target rods 10. The high-frequency coil 8 was supplied with a high-frequency current having a frequency of 3.5 MHz. The power supply was adjusted so that the target rod 10 did not soften and the adhering glass particles became well transparent. During the deposition of the glass particles, the target rod 10 was rotated and displaced in the longitudinal direction. Tar The rotation speed of the get bar 10 was 60 rpm, the moving speed in the longitudinal direction was 75 mmZmin, and the moving range was 500 mm. The glass particles were deposited until the outer diameter of the glass particles adhering to the target rod 10 became 1.1 times the outer diameter of the original target rod 10. Table 2 shows the adhesion efficiency of the five types of samples thus obtained.
[0045] [表 2] [0045] [Table 2]
Figure imgf000013_0001
Figure imgf000013_0001
[0046] 表 2に示すように、付着効率は 10〜38%と全般に低ぐ特にターゲット棒 10の外径 力 S小さい場合は付着効率が著しく低下することが確認された。また、各試料を作製す る度にプラズマトーチ 100の内部を検査したところ、原料ガス供給管 2の先端側の端 面 5にガラス微粒子が堆積して、さらにその上に透明なガラスが堆積して垂れ下がつ てきていた。更に、内側管 3の内面においても、プラズマガスの出口付近にガラス微 粒子が堆積して層をなして、一部はひび割れを生じて破片が飛散していた。この破 片により、作製したガラス母材を透明ガラス化する工程において気泡が発生すること が判った。従って、このプラズマトーチ 100で一定水準の製品品質を維持するには、 ガラス微粒子の堆積を行う毎に分解して清掃しなければならな力つた。  [0046] As shown in Table 2, it was confirmed that the adhesion efficiency is remarkably lowered when the adhesion efficiency is generally low at 10 to 38%, particularly when the outer diameter force S of the target rod 10 is small. Further, when the inside of the plasma torch 100 was inspected every time each sample was produced, glass fine particles were deposited on the end surface 5 on the front end side of the source gas supply pipe 2, and transparent glass was further deposited thereon. The drooping was coming. Further, on the inner surface of the inner tube 3, glass particles were deposited near the plasma gas outlet to form a layer, and some cracks were generated and fragments were scattered. It was found that this fragment generated bubbles in the process of converting the produced glass base material into a transparent glass. Therefore, in order to maintain a certain level of product quality with this plasma torch 100, it was necessary to disassemble and clean each time glass particles were deposited.
[0047] 図 5に実施例および比較例の付着効率とターゲット径との関係をグラフにして示す 。同図に示すように、図 3に示した構造を有するプラズマトーチ 200を用いることにより 、付着効率が 2〜5倍に向上される。また、プラズマトーチ 200の清掃作業に要する 時間も考慮すると、プラズマトーチ 100およびプラズマトーチ 200による作業効率の 相違はさらに大きくなる。  FIG. 5 is a graph showing the relationship between the adhesion efficiency and the target diameter in Examples and Comparative Examples. As shown in the figure, by using the plasma torch 200 having the structure shown in FIG. 3, the adhesion efficiency is improved 2 to 5 times. Further, considering the time required for the cleaning work of the plasma torch 200, the difference in work efficiency between the plasma torch 100 and the plasma torch 200 is further increased.
[0048] 以上、本発明を実施の形態を用いて説明したが、本発明の技術的範囲は上記実 施の形態に記載の範囲には限定されない。上記実施の形態に、多様な変更または 改良を加え得ることが当業者に明らかである。その様な変更または改良を加えた形 態も本発明の技術的範囲に含まれ得ることが、請求の範囲の記載力も明らかである。 産業上の利用可能性 [0048] While the present invention has been described using the embodiment, the technical scope of the present invention is as described above. The range described in the embodiments is not limited. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is clear that the embodiment described above can be included in the technical scope of the present invention with such changes or improvements. Industrial applicability
プラズマトーチの特徴を活力した高品質な固体物質の合成を、長期間にわたって 安定に実施できる。従って、例えば、光ファイバ用ガラス母材の生産性向上に寄与す る。  The synthesis of high-quality solid materials that make the most of the characteristics of plasma torches can be performed stably over a long period of time. Therefore, for example, it contributes to the productivity improvement of the glass preform for optical fibers.

Claims

請求の範囲 The scope of the claims
[1] 後端カゝら原料ガスおよび前記原料ガスに対して不活性なキャリアガスの混合原料 ガスを供給され、先端から前記混合原料ガスを吐出する第 1管と、  [1] A first pipe that is supplied with a source gas and a source gas mixed with a carrier gas inert to the source gas and discharges the source gas from the tip,
前記第 1管を包囲して配置され、前記第 1管の外面との間において、後端から不活 性ガスを供給され、先端から前記不活性ガスを吐出する第 2管と、  A second pipe that is disposed so as to surround the first pipe, is supplied with an inert gas from a rear end, and discharges the inert gas from a front end between the first pipe and the outer surface of the first pipe;
前記第 2管を包囲して形成され、前記第 2管の外面との間において、後端から不活 性ガスで希釈された副原料ガスを供給され、先端から前記副原料ガスを吐出する第 3管と、  A secondary material gas that is formed surrounding the second pipe and is diluted with an inert gas is supplied from the rear end to the outer surface of the second pipe, and the secondary raw material gas is discharged from the front end. With 3 tubes,
前記第 3管の外側に形成され、前記第 3管の外面との間において、冷却媒体が流 通する第 4管と  A fourth pipe formed outside the third pipe and through which a cooling medium flows between an outer surface of the third pipe;
を含む 4重管構造を有し、吐出した前記混合原料ガスおよび前記副原料ガスから固 体物質を合成する高周波誘導熱プラズマトーチであって、  A high-frequency induction thermal plasma torch that synthesizes a solid substance from the discharged mixed raw material gas and the auxiliary raw material gas,
前記先端の近傍において前記第 4管の外側に配置された高周波コイルを更に備え 、且つ、前記第 1管、前記第 2管の先端が、前記第 4管において前記高周波コイルが 配置された区間よりも後端側に後退している高周波誘導熱プラズマトーチ。  A high-frequency coil disposed outside the fourth tube in the vicinity of the distal end, and the distal ends of the first tube and the second tube are from a section where the high-frequency coil is disposed in the fourth tube; A high frequency induction thermal plasma torch that is also retracted to the rear end.
[2] 前記第 1管、前記第 2管および前記第 3管の少なくともひとつが、窒化ケィ素または 窒化アルミニウムを含む材料で形成される請求項 1に記載の高周波誘導熱プラズマ トーチ。 [2] The high frequency induction thermal plasma torch according to claim 1, wherein at least one of the first tube, the second tube, and the third tube is formed of a material containing silicon nitride or aluminum nitride.
[3] 前記第 1管および前記第 2管の低なくともひとつが、耐熱性および耐酸性を有する 合金で形成されたブロックにより支持され、且つ、前記ブロックが水冷されている請求 項 1に記載の高周波誘導熱プラズマトーチ。  [3] The at least one of the first pipe and the second pipe is supported by a block formed of an alloy having heat resistance and acid resistance, and the block is water-cooled. High frequency induction thermal plasma torch.
[4] 後端カゝら原料ガスおよび前記原料ガスに対して不活性なキャリアガスの混合原料 ガスを供給され、先端から前記混合原料ガスを吐出する第 1管と、 [4] A first pipe that is supplied with a mixed raw material gas of a raw material gas and a carrier gas inert to the raw material gas from the rear end, and discharges the mixed raw material gas from the leading end;
前記第 1管を包囲して配置され、前記第 1管の外面との間において、後端から不活 性ガスを供給され、先端から前記不活性ガスを吐出する第 2管と、  A second pipe that is disposed so as to surround the first pipe, is supplied with an inert gas from a rear end, and discharges the inert gas from a front end between the first pipe and the outer surface of the first pipe;
前記第 2管を包囲して形成され、前記第 2管の外面との間において、後端から不活 性ガスで希釈された副原料ガスを供給され、先端から前記副原料ガスを吐出する第 A secondary material gas that is formed surrounding the second pipe and is diluted with an inert gas is supplied from the rear end to the outer surface of the second pipe, and the secondary raw material gas is discharged from the front end.
3管と、 前記第 3管の外側に形成され、前記第 3管の外面との間において、冷却媒体が流 通する第 4管と With 3 tubes, A fourth pipe formed outside the third pipe and through which a cooling medium flows between an outer surface of the third pipe;
を含む 4重管構造を有し、  Has a quadruple tube structure including
前記先端の近傍において前記第 4管の外側に配置された高周波コイルを更に備え 、且つ、前記第 1管、前記第 2管の先端が、前記第 4管において前記高周波コイルが 配置された区間よりも後端側に後退している高周波誘導熱プラズマトーチを用いて、 吐出した前記混合原料ガスおよび前記副原料ガスから固体物質を合成する固体物 質の合成方法。  A high-frequency coil disposed outside the fourth tube in the vicinity of the distal end, and the distal ends of the first tube and the second tube are from a section where the high-frequency coil is disposed in the fourth tube; A method for synthesizing a solid substance, wherein a solid substance is synthesized from the discharged mixed raw material gas and the auxiliary raw material gas using a high frequency induction thermal plasma torch which is also retracted to the rear end side.
[5] 前記第 1管、前記第 2管および前記第 3管の少なくともひとつが、窒化ケィ素または 窒化アルミニウムを含む材料で形成される請求項 4に記載の固体物質の合成方法。  5. The method for synthesizing a solid substance according to claim 4, wherein at least one of the first tube, the second tube, and the third tube is formed of a material containing silicon nitride or aluminum nitride.
[6] 前記第 1管および前記第 2管の少なくとも一方が、耐熱性および耐酸性を有する合 金で形成されたブロックにより支持され、且つ、前記ブロックが水冷されている請求項[6] The at least one of the first pipe and the second pipe is supported by a block formed of a heat-resistant and acid-resistant alloy, and the block is water-cooled.
4に記載の固体物質の合成方法。 4. The method for synthesizing a solid substance according to 4.
[7] 前記原料ガスがケィ素化合物を含み、前記副原料ガスが酸素を含む請求項 4から 請求項 6までのいずれか 1項に記載の固体物質の合成方法。 [7] The method for synthesizing a solid substance according to any one of [4] to [6], wherein the source gas contains a silicon compound and the auxiliary source gas contains oxygen.
[8] 前記ケィ素化合物が四塩ィ匕ケィ素を含む請求項 7に記載の固体物質の合成方法。 8. The method for synthesizing a solid material according to claim 7, wherein the key compound includes tetrasalt key.
[9] 前記固体物質が、石英ガラスである請求項 4力 請求項 8までのいずれか 1項に記 載の固体物質の合成方法。 [9] The method for synthesizing a solid substance according to any one of claims 4 to 8, wherein the solid substance is quartz glass.
[10] 前記固体物質が、不純物をドープされた石英ガラスである請求項 4力 請求項 8ま でのいずれか 1項に記載の固体物質の合成方法。 10. The method for synthesizing a solid material according to claim 4, wherein the solid material is quartz glass doped with impurities.
[11] 前記不純物がフッ素を含む請求項 10に記載の固体物質の合成方法。 11. The method for synthesizing a solid substance according to claim 10, wherein the impurity contains fluorine.
[12] 前記固体物質が、光ファイバ用ガラス母材である請求項 4力 請求項 11までのい ずれか 1項に記載の固体物質の合成方法。 [12] The method for synthesizing a solid substance according to any one of claims 4 to 11, wherein the solid substance is a glass base material for an optical fiber.
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