| 摘要 |
PROBLEM TO BE SOLVED: To provide a process and a device for controlling the internal pressure in a silica tube when manufacturing an optical fiber precursor by a chemical vapor deposition(CVD) method. SOLUTION: The apparatus for controlling the internal pressure in the silica tube by the CVD method has an exhaust box 6 equipped with an exhaust pipe 9 equipped with an electrically driven valve 11 in the middle of the pipe, a pressure sensor 7 for detecting the pressure inside the box and an inert gas- injecting nozzle 8 for injecting an inert gas into the box, a rotational connecting tube 3 which holds the end of the silica tube 1 opposite to the material gas- supplying side and is supported to achieve an airtight connection with the interior of the exhaust box 6 and an inert gas-supplying channel equipped with a mass flow control valve 10 which supplies an appropriate amount of inert gas from the material gas-supplying end of the silica tube 1. |
