Halogen

The halogen lamp is a particular incandescent lamp but it has some essential characteristics, which differentiate it from the common ones. Iodine, kripton and, sometimes, xenon are added to the gas inside the bulb in order to allow the filament to get warm up to 3000 k. This increases the bright efficiency and rises up the color temperature. In the halogen lamps, tungsten evaporates because of the high temperature and reacts with gas, creating tungsten halide. Afterwards the compound comes in contact with the incandescent filament, decomposes itself and leaves tungsten on the filament realizing a cycle (called halogen cycle). This way the long-life of an halogen lamp may double the long-life of an incandescent normal one, although the filament is a lot warmer. 

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