Abstract: A low wattage metal halide capsule shape having a cylindrical shape geometry with asymmetrical regions behind the anode and cathode for direct current operation is disclosed. The disclosure concerns several arc tube geometries to encourage internal convective flow in small, direct current arc discharge lamps.

Abstract: A method to press mold heavy wall metal halide lamps (with reduced glass mass in end seals) is disclosed. Wall temperature in a metal halide lamp may be normalized by varying the wall thickness in relation to the heat falling on the interior surface, and the heat lost through the exterior surface. Increasing the wall thickness, acts to spread the heat, and decrease the wall temperature. Thinning the wall, acts to concentrate the heat, and increase the wall temperature. By press molding the lamp glass and simultaneously reducing the glass mass in the end seals, the desired wall thickness may be obtained without excessive heat loss in the end seals to result in an isothermal internal profile.