The tungsten that evaporates reacts chemically with the halogen, thus giving rise to a tungsten halogen. The high temperature of the filament (about 2,500 ° C) involves the subsequent dissociation of the tungsten halogen, in halogen and metallic tungsten. The tungsten therefore falls on the filament, partially regenerating it, while the freed halogen allows the continuation of the cycle as shown by Lighting Installation in Los Angeles.
For these chemical reactions to be possible, the filament temperature must not fall below 2,000 ° C. To withstand these temperatures, the bulb of the halogen lamps is made of quartz. For an in-depth look at the main technical parameters of the lamps, see the Efficiency and lighting quality page in the menu on the right. Average life longer than traditional incandescent lamps (2,000-4,000 hours) and the phenomenon of bulb blackening is avoided.