| 摘要 |
The present invention relates to an induction plasma torch of the type used in plasma deposition methods for depositing pure or doped silica when manufacturing preforms for optical fibers, the plasma torch comprising: a "reaction" tube inside which a plasma production zone is located; means for injecting reagents for forming the pure or doped silica to be deposited into the tube towards the plasma production zone; feed means for feeding plasma-generating gases into the tube towards the plasma production zone; and an induction coil surrounding the tube for supplying the energy required to form the plasma; wherein the tube is protected against the thermal cycles due to variations in the temperature inside the tube by means of a protective lining deposited on the inside wall of the reaction tube at the plasma production zone so as to surround the zone, the lining being made of a material based on silica, and having a thickness of less than 2 mm.
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