Metal halide arc discharge lamp with shroud of reduced mass

摘要

A metal halide arc discharge lamp (10) having a lamp envelope (12) and an arc tube (14) mounted within the envelope; a shroud (20) surrounding the arc tube (14); electrical leadins (26, 28) for supplying electrical energy to the arc tube (14); and a chemical fill within the arc tube to produce light when an arc is formed within the arc tube; the improvement comprising: the shroud (20) having a given thickness T and a given inside diameter ID having a relationship such that T is less than 2 mm and ID/T is less than 22.