Patent ID: 6510710
Filing Date: 2003-01-28
Classification: C03B,C03C

Abstract:
A multi-tube delivery system employed to introduce vapors of glass constituents into a reaction zone, said multi-tube delivery system comprising:a plurality of concentrically arranged vapor delivery tubes with a central vapor delivery tube having an upstream end and a downstream end; a holding vessel loaded inside said central vapor delivery tube, and having a cavity that holds a solid rare earth halogen and exposes a predetermined two-dimensional surface area of said solid rare earth halogen to a temperature sufficient to vaporize solid rare earth halogen material from said predetermined two-dimensional surface area thereof, said cavity being configured so as to maintain said predetermined two-dimensional surface area of said solid rare earth halogen constant, as material of said solid rare earth halogen is vaporized from said predetermined two-dimensional surface area thereof; a stream of inert gas entering said central vapor delivery tube from said upstream end and exiting said downstream end; a vapor of glass-forming material being introduced into said reaction zone by passage through a vapor delivery tube other than said central vapor delivery tube; and wherein said downstream end of said central delivery tube is sealed with a frit, said frit being permeable to a rare earth halide-laden vapor carried by said stream of inert gas in said central delivery tube, but preventing said vapor of glass-forming material from entering into said central vapor delivery tube.