A halogen lamp, also known as a tungsten halogen, quartz-halogen, or quartz iodine lamp, is an incandescent lamp that uses a tungsten filament surrounded by a small amount of halogen gas, such as iodine or bromine, to improve its efficiency and extend its lifespan. The halogen cycle, which involves the regenerative re-deposition of tungsten onto the filament, allows halogen lamps to operate at higher temperatures and produce a brighter and more efficient light compared to traditional incandescent lamps.
Key points about halogen lamps:
Filament and bulb construction: Halogen lamps have a tungsten filament enclosed in a transparent quartz or high-temperature glass envelope. The use of quartz allows the lamp to withstand higher temperatures, making it suitable for more efficient operation.
Halogen gas: A small amount of halogen gas, typically iodine or bromine, is sealed inside the lamp envelope. The presence of halogen gas is a crucial feature that enables the halogen cycle and contributes to the lamp's longevity and brightness.
Halogen cycle: During operation, as the tungsten filament gets hot, some tungsten atoms evaporate. In a halogen lamp, the halogen gas captures these evaporated tungsten atoms, preventing them from depositing on the lamp's envelope. Instead, the tungsten is redeposited on the filament, maintaining its integrity and allowing the lamp to operate at higher temperatures without significant filament deterioration.
Higher color temperature: Halogen lamps produce light with a higher color temperature compared to standard incandescent lamps, resulting in a whiter and brighter light output. This makes them suitable for applications where color accuracy and visual appeal are important.
Efficiency: Halogen lamps are more energy-efficient than traditional incandescent lamps, primarily due to the halogen cycle. The regenerative process allows the filament to operate at higher temperatures, producing more visible light for a given amount of electrical power.
Versatility: Halogen lamps are available in various shapes and sizes, making them suitable for a wide range of applications, including general lighting, spotlights, floodlights, desk lamps, and automotive lighting.
Instant on: Halogen lamps provide instant and full illumination when turned on, without the warm-up time required by some other types of lighting technologies.
Dimmability: Halogen lamps are often dimmable, allowing users to control the intensity of the light based on their preferences or lighting needs.
Despite their efficiency and brightness, halogen lamps have faced competition from more energy-efficient lighting technologies, such as compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs). In many regions, regulations aimed at improving energy efficiency have led to the phasing out or restriction of certain types of halogen lamps.