In the method for manufacturing a glass-fine-particle-deposited body according to the present invention, at least a part of a gas supplying pipe 25 from a temperature controlled booth 24 to a burner 18 for cladding is temperature-controlled so that the temperature at the burner side becomes high and temperature gradient becomes 5 C./m or more. The temperature control is performed so that the temperature gradient becomes preferably 15 C./m or more, more preferably 25 C./m or more. Specifically, the part is controlled to the predetermined temperature gradient by winding a tape heater 26 that is a heating element on the outer circumference of the gas supplying pipe 25 from the temperature controlled booth 24 to the burner 18 for cladding and temperature-controlling the tape heater 26.

The invention provides a production method for a glass particulate deposit M which includes a deposition step where a starting rod 111 and a burner 222 for production of glass particles 130 are installed in a reactor 102, a glass source material is introduced into the burner 222, the glass source material is subjected to flame thermal decomposition in the flame formed by the burner 222 to thereby form glass particles 130, and the formed glass particles 130 are deposited on the starting rod 111 to produce a glass particulate deposit M. In the deposition step of the production method, at least two ejecting ports 231 are provided per one burner 222 for ejecting the glass source material from the burner 222, and a flow rate of the glass source material jetting out through one glass source material ejecting port 231 is from 4 m/s to 60 m/s.

A method is provided for producing a glass fine particle deposit by a VAD method using a core deposition burner and a cladding deposition burner disposed adjacent to the core deposition burner. The cladding deposition burner including five cylindrical tubes having different outer diameters and concentrically superimposed on one another and a group of small-diameter nozzles arranged in a ring shape in a third region from the inner side. The method includes flowing, in the cladding deposition burner, a glass raw material gas and a combustion supporting gas in a first region from the inner side, air in a second region from the inner side, a combustible gas in the third region from the inner side, a combustion supporting gas in the group of small-diameter nozzles, an inert gas in a fourth region from the inner side, and a combustion supporting gas in a fifth region from the inner side, respectively.

A method for producing an optical fiber includes stabilizing a burner flame using a multi-nozzle burner. The multi-nozzle burner includes a raw material gas ejection port in a central part for ejecting a raw material gas. The multi-nozzle burner includes a seal gas ejection port on an outer side of the raw material gas ejection port for ejecting a seal gas. The multi-nozzle burner includes a combustible gas ejection port on an outer side of the seal gas ejection port for ejecting a combustible gas. The multi-nozzle burner includes a plurality of small diameter combustion supporting gas ejection ports surrounding the seal gas ejection port in the combustible gas ejection port for ejecting a combustion supporting gas. A gas flow rate of the raw material gas ejection port is V1 and a gas flow rate of the seal gas ejection port is V2, and 1>V2/V1>0.05.

In the method for manufacturing a glass-fine-particle-deposited body according to the present invention, at least a part of a gas supplying pipe 25 from a temperature controlled booth 24 to a burner 18 for cladding is temperature-controlled so that the temperature at the burner side becomes high and temperature gradient becomes 5 C./m or more. The temperature control is performed so that the temperature gradient becomes preferably 15 C./m or more, more preferably 25 C./m or more. Specifically, the part is controlled to the predetermined temperature gradient by winding a tape heater 26 that is a heating element on the outer circumference of the gas supplying pipe 25 from the temperature controlled booth 24 to the burner 18 for cladding and temperature-controlling the tape heater 26.

In the method for manufacturing a glass-fine-particle-deposited body according to the present invention, at least a part of a gas supplying pipe 25 from a temperature controlled booth 24 to a burner 18 for cladding is temperature-controlled so that the temperature at the burner side becomes high and temperature gradient becomes 5 C./m or more. The temperature control is performed so that the temperature gradient becomes preferably 15 C./m or more, more preferably 25 C./m or more. Specifically, the part is controlled to the predetermined temperature gradient by winding a tape heater 26 that is a heating element on the outer circumference of the gas supplying pipe 25 from the temperature controlled booth 24 to the burner 18 for cladding and temperature-controlling the tape heater 26.

A method and an apparatus for producing a porous glass preform by using organosiloxane raw material is provided. The apparatus for producing the porous glass preform 12 according to the present embodiment is configured to mix organosiloxane in a liquid state being a raw material with a carrier gas in a vaporizer 6, heat this mixture to be vaporized, supply this vapor to a burner 13 as a gas raw material, and produce a porous glass preform by depositing a glass fine particle produced by combusting the gas raw material on a starting material, herein the apparatus for producing a porous glass preform includes a moisture removing apparatus 8 configured to remove moisture in the carrier gas and supply the vaporizer with the carrier gas.