High-intensity discharge lamp

High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with noble gas and often also contains suitable metal or metal salts, which emit the desired spectrum of light when excited (such as mercury, sodium, or sodium iodide).

Source: Wikipedia — High-intensity discharge lamp (CC BY-SA 4.0)