Metal halide arc discharge lamp with means for suppressing convection currents within the outer envelope and methods of operating and constructing same

摘要

A metal halide arc discharge lamp having a gaseous fill within the outer envelope and means for suppressing convection currents within such fill; and methods of operating and constructing such lamps. A light-transmissive sleeve or enclosure surrounding the arc tube laterally and about at least one end thereof is so shaped and mounted with respect to the arc tube as to insure that the Rayleigh Number, a quantitative measure of convective flow, in the atmosphere laterally surrounding the arc tube will be less than 5x104 during operation of the lamp whereby excessive convective heat loss in such lamp will be effectively suppressed.