| 摘要 |
PURPOSE:To improve reaction efficiency for forming glass film remarkably in the titled process wherein starting materials for forming glass is fed to plasma flame through an introducing pipe for the starting materials, by regulating the attaching angle of said introducing pipe. CONSTITUTION:O2 is fed to high frequency plasma torch 1 in the arrow direction to generate plasma flame. Reactant gas is fed from a reactant gas introducing pipe 2 attached inclinedly and fed confrontingly to the top end of the flame into a reaction chamber 4 below the plasma flame to cause reaction and a glass film 7 is formed on the external periphery of a target bar 6 supported by a lathe 5 and revolved and in a longitudinal direction. When a reactant gas having the same compsn. is used, the difference of specific refractive index of the film 7 is varied depending on the angle theta formed by an orthogonal plane 20 to the axis 19 of the plasma flame of the pipe 2 and the a pipe 2 confronting the axis 19. If the angle theta for attaching the pipe 2 is regulated to 0<theta<30 deg., the reaction efficiency is improved remarkably, and decrease of the amt. of doping is inhibited. The control of refractive index is possible by the control of the angle theta. |
