Electrode for metal halide discharge lamp

A low power metal halide discharge lamp having an improved electrode structure. Two elongated electrodes fabricated of a doped tungsten each extend axially through a respective neck of a bulb into an arc chamber. Each of electrode comprises a lead-in wire having a diameter ranging between about 0.003 to 0.018 inches that enters the arc chamber. A post member is mounted on the lead-in wire, out of contact with the associated neck, and is preferably welded to the lead-in. The post member has a flat distal surface for transferring heat to vapors in said arc chamber. It is larger in diameter than its associated lead-in wire, and has a diameter in a range of 0.005 to 0.040 inches. The flat distal surfaces of the two post members face one another in spaced apart relationship, the space therebetween forming an arc gap. In operation the distal surfaces of the post members have relatively large areas in contact with vapors in the arc chamber for heat transfer, and the heat is sufficiently dispersed in the distal region of the post members to prevent burn back.