The induction lamp, electrodeless lamp, or electrodeless induction lamp is a gas-discharge lamp in which an electric or magnetic field transfers the power required to generate light from outside the lamp envelope to the gas inside. This is in contrast to a typical gas discharge lamp that uses internal electrodes connected to the power supply by conductors that pass through the lamp envelope. Eliminating the internal electrodes provides two advantages:
- Extended lamp life (internal electrodes are the most limiting factor in lamp life, since their metal content will get sputtered onto the lamp ends every time they are turned on)[citation needed]
- Ability to use higher-efficiency light-generating substances that would react with internal metal electrodes in conventional fluorescent lamps[citation needed]
Two systems are common: plasma lamps, in which microwaves or radio waves, energizes a bulb filled with sulfur vapor or metal halides, and fluorescent induction lamps, which are like a conventional fluorescent lamp bulb that induces current with an external or an internal coil of wire via electromagnetic induction.