Light Bulb Types
HID, short for high-intensity discharge bulbs are gas discharge lamps that create light through an electrical discharge from two electrodes and ionized gas. An additional type of gas is often added and this serves its purpose by making it easy to classify the top three types of HID bulbs: metal halide, sodium and mercury.
These types of HID lamps have a reputation of being very efficient as well as being long-lived. A typical HID bulb requires a ballast to generate the initial electrical surge needed to start producing light as well as serving as power regulators during its normal operation.
The technology needed to create gas-discharge bulbs and lamps has been with us for roughly 300 years, and it is because of these principles that experts were guided to making other innovations that led to the invention of other lights such as neon and fluorescent bulbs. The person responsible for the invention of gas-discharge bulbs is Francis Hauksbee, who performed a demonstration of the technology some time in 1705. During those times, the lamps were usually filled with air but due to technological progress, they have found out that the output of the lamp could be increased by incorporating noble gases like neon, argon, krypton, or xenon. The experimentation of gas mixtures as well as improved electrodes have effectively increased an HID bulb's light output, but nonetheless the basics of the discharge-bulb still remains the same.
Manner of Operation
By sending an arc of electricity between tungsten electrodes housed within an arc tube, the HID bulb produces light. The arc tube, which is typically made of quartz, is filled with mixtures of metal salts and gases. The electric arc is created by an initial surge of energy, which is then guided by the gas within the bulb. The metal salts get heated by the arc and plasma is then created. Plasma significantly increases the light output, which is produced by the arc, which in turn results in a light source that is considerably more efficient at creating actual light instead of just heat.
HID bulbs and lamps are generally used in places where creating as much light as possible is critical. These applications include gymnasiums, streetlights, warehouses, retail facilities, stadiums and even rooms dedicated to plant growth. In recent times, HID lamps are used as headlights for high-end vehicles. Because HID bulbs naturally produce light with either a warm white/yellow or blue/cool white hue, they aren't used in places where the aesthetics of light is critical.