Patent ID: 8192807

Claim:
A method for making an optical fiber preform, comprising: injecting a plasma source gas into the first end of a tubular member having a central longitudinal axis; generating a radio frequency ring plasma flame having a temperature of at least 3,000C.° with said plasma source gas flowing through a plasma gas feeder nozzle, said plasma gas feeder nozzle comprising: a flow direction control structure; an inner tube, and an outer tube, wherein the flow direction control structure injects said plasma source gas between said inner tube and said outer tube to produce a swirl plasma gas stream that establishes said radio frequency ring plasma flame, such that at least a portion of said radio frequency ring plasma flame is directed radially toward said inner surface of said tubular member; traversing said tubular member along said longitudinal axis relative to said plasma flame; depositing at least one unconsolidated soot material layer on the interior surface of said tubular member by introducing reagent chemicals into said plasma flame, said reagent chemicals being introduced into said first end of said tubular member at a predetermined distance from said plasma flame; and fusing all of said unconsolidated soot material layer into a vitreous glass material on said interior surface of said tubular member.