Kylmäkatodiputken

Kylmäkatodiputki, often translated as cold cathode tube, is a type of gas-discharge lamp that emits light without the need for preheating the cathode. Unlike hot cathode tubes, which require a filament to be heated to a high temperature to release electrons, cold cathode tubes operate by applying a high voltage across electrodes in a gas-filled envelope. This high voltage causes the gas to ionize, creating a plasma that then emits light.

The cathode in a cold cathode tube is typically made of a material that readily emits electrons when struck by positive ions in the plasma. Common materials include certain metals. The gas inside the tube can vary, with noble gases like neon, argon, and xenon being frequently used, often mixed with other gases to achieve specific colors or operating characteristics.

Cold cathode tubes are known for their long lifespan, quick start-up time (as no preheating is required), and ability to operate in low-temperature environments. They are often used in applications where these features are advantageous, such as decorative lighting, signage, and as backlights for displays, particularly in older LCD technologies. The characteristic glow of neon signs is a well-known example of cold cathode illumination. However, they generally require higher operating voltages than hot cathode lamps.