Influence of Mount Structure on Performance of Ceramic Metal Halide Lamps

A family of 20 000-h-long-life medium-wattage ceramic discharge metal halide lamps have been developed. It is found that arc bending is primarily responsible for the highest failure mode, body cracking (50%), and that the electromagnetic force is the root cause for arc bending in vertically operating lamps. A new mount structure was constructed to reduce body cracking. The life test results and arc tube wall temperature measurements as well as spectroscopic analysis have clearly demonstrated that the new and patented structure reduces arc tube body cracks, improves lumen maintenance, and extends lamp life.