Metal halide lamp with rhenium skin on tungsten electrode

摘要

The high-pressure metal halide discharge lamp has opposite tungsten electrodes (5) carried by electrode rods (7). These rods (7) have a first portion (71) of tungsten adjacent the electrodes (5) and a second portion (72) having a core of tungsten and a skin of at least 90% by weight of rhenium. Their common boundaries are at a location having during operation a temperature in the range of 1900-2100 K. The gas filling contains metal oxyhalide and is devoid of rare earth metal compounds. The lamp has a long life and a high luminous maintenance.