High brightness, low wattage, high pressure, metal vapor discharge lamp

A single ended, high pressure, low wattage, metal vapor discharge lamp having a transparent body defining an arc chamber and containing an arc generating and sustaining medium;

• adjacent first and second electrodes sealed in said body and projecting into said arc chamber, the terminal ends of said electrodes defining an arc region, said lamp being characterized by:
• the distance between said terminal ends being substantially equal to the distance of said terminal ends from an upper surface of said arc chamber, and an arc generating and sustaining medium comprising an effective amount of mercury to achieve the predetermined arc voltage;
• an arc constrictor selected from the group of lanthanides, actinides and thorium;
• a halide;
• and a complete absence of alkali metals.