Coated arc tube for sodium vapor lamp
First Claim
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1. A hollow alumina tube suitable for use as an arc tube for a sodium vapor arc discharge lamp, wherein an interior surface and an exterior surface of said tube are essentially continuously coated with a coating of oxide of at least one metal selected from the group consisting of Y, Hf, La, Zr, Dy, Sc and mixture thereof.
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Abstract
High pressure sodium arc vapor discharge lamps employing an alumina arc tube exhibit less voltage rise and better lumen maintenance over the life of the lamp when the arc tube is coated with an oxide of a metal selected from the group consisting essentially of yttrium, zirconium, hafnium, lanthanum, dysprosium, scandium and mixture thereof.
26 Citations
12 Claims
- 1. A hollow alumina tube suitable for use as an arc tube for a sodium vapor arc discharge lamp, wherein an interior surface and an exterior surface of said tube are essentially continuously coated with a coating of oxide of at least one metal selected from the group consisting of Y, Hf, La, Zr, Dy, Sc and mixture thereof.
- 3. A hollow alumina tube suitable for use as an arc discharge tube for a sodium vapor arc discharge lamp, wherein said alumina tube is selected from the group consisting of polycrystalline alumina and single crystal alumina and wherein at least one of an interior surface and an exterior surface is essentially continuously coated with a transparent oxide of a metal selected from the group consisting of Y, Hf, La, Zr, Dy, Sc and mixture thereof.
- 6. A high pressure sodium vapor arc discharge lamp comprising an alumina arc tube containing sodium and a pair of spaced apart electrodes hermetically sealed within wherein said alumina arc tube is made of polycrystalline alumina or single crystal alumina having both an interior surface and exterior surface and wherein said interior surface, said exterior surface or both said interior and said exterior surfaces of said arc tube are essentially continuously coated with a transparent oxide of a metal selected from the group consisting of Y, Hf, La, Zr, Dy, Sc and mixture thereof.
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12. A hollow alumina tube suitable for use as an arc discharge tube for a sodium vapor arc discharge lamp, wherein said alumina tube is selected from the group consisting of polycrystalline alumina and single crystal alumina and wherein at least one of an entire interior surface and an entire exterior surface is essentially continuously coated with an oxide of a metal selected from the group consisting of Y, Hf, La, Zr, Dy, Sc and mixture thereof.
Specification