Patent DE-102009010498-A1 (DE)
Title: Multi-nozzle, tubular plasma deposition burner for producing preforms as semi-finished products for optical fibers, has means for feeding a dopant using a precursor gas and perpendicular orientation of the burner gas longitudinal axis
Inventor: AUTH MATTHIAS
IPC: H05H1/36
Filed: 2009-02-25
Abstract: The multi-nozzle, tubular plasma deposition burner (1) comprises means for feeding a dopant using a precursor gas and a substantially perpendicular orientation of the burner gas longitudinal axis relative to the center axis of a substrate (4), and a precursor gas guidance, where a media stream containing glass starting material and a carrier gas is fed to the burner. A first partial stream of a first gas or precursor gas is fed to the plasma and to the substrate via a nozzle running in the burner longitudinal axis. The multi-nozzle, tubular plasma deposition burner (1) comprises means for feeding a dopant using a precursor gas and a substantially perpendicular orientation of the burner gas longitudinal axis relative to the center axis of a substrate (4), and a precursor gas guidance, where a media stream containing glass starting material and a carrier gas is fed to the burner. A first partial stream of a first gas or precursor gas is fed to the plasma and to the substrate via a nozzle running in the burner longitudinal axis and a second partial stream of the first gas or of another gas or gas mixture such as precursor gas, is fed to the plasma and the substrate via another nozzle (5). The gas or gas mixtures are fed in such a way that the partial streams combine in the vicinity of the substrate. The further nozzle is formed as multiple nozzle comprising two or more individual nozzles staggered for burner longitudinal axis. The further nozzle or nozzle pairs are arranged in an angle from the burner longitudinal axis. The nozzle pairs comprise group of individual nozzle as nozzle chain, which faces opposite to the nozzle pair in a given angle. The individual nozzle or nozzle chain of the nozzle pair has angle positions adjustable to each other. The further nozzle or nozzle pair is present external of the burner related to the substrate next to burner tube (3) in an area between the substrate surface and the burner. The further nozzle or the nozzle chain produces tangential gas stream component related to the tube configuration of the burner. The further nozzle, the nozzle pair or the respective nozzle chain is movable and adjustably guided. The nozzle running in burner longitudinal axis comprises two thick walled tubes guidable to each other. The tubes are positioned concentrically to each other. The wall strength of the tube is 2-20 mm. The interior of the tube arrangement possesses a large interval from plasma area as external tube of the tube arrangement. The precursor gas guidance comprises a chamber for mixing and/or soothing the gas stream. The nozzle chain comprises plate form and nozzle holes. The burner arrangement is surrounded by nitrogen curtain. The nozzle running in the burner longitudinal axis is formed as nozzle group for partial streams. The nozzle groups comprise individual nozzles, which possess different or changeable nozzle cross-section or cross-sectional area. The further nozzles or the individual nozzles are formed as slot nozzle or as concentric nozzle with beam shaping characteristics. The nozzle chain is formed as multi-line nozzle chain with nozzles lying to each other. The tangential gas stream components pass in rotation direction of the plasma helix. The further nozzle, the nozzle pair or the respective nozzle chain is adjustable in the movement direction of the substrate. The chamber is formed as pre-chamber on the end of the burner removing from the substrate in burner longitudinal direction with gas supply. An independent claim is included for a method for producing preforms as semi-finished products for optical fibers.