Patent ID: 7057350

Claim:
An arc discharge metal halide lamp for use in selected lighting fixtures, said lamp comprising: a discharge chamber having visible light permeable walls of a selected shape bounding a discharge region through which walls a pair of electrodes are supported in said discharge region spaced apart from one another by a distance L e with said walls about said discharge region having an average diameter over L e equal to D so as to satisfy L e /D<2.75 with D exceeding 2.0 mm; and ionizable materials provided in said discharge region of said discharge chamber comprising a noble gas, a metal halide and mercury in an amount sufficiently small to result in a voltage drop between said electrodes during lamp operation that is less than 110 V rms at a selected value of electrical power dissipation in said lamp such that wall loading of said discharge chamber during operation equals or exceeds 33 W/cm 2 .