Electron-stimulated luminescence

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For the phenomenon in materials science, see Cathodoluminescence.
An ESL lamp.

Electron-stimulated luminescence (ESL) is light produced by cathodoluminescence,[1][2][3][4] i.e. by a beam of electrons made to hit a fluorescent phosphor surface. This is also the method used to produce light in a cathode ray tube (CRT), but, unlike CRTs, ESL lamps do not include magnetic or electrostatic means to deflect the electron beam.[5]

A cathodoluminescent light has a transparent glass envelope coated on the inside with a light-emitting phosphor layer. Electrons emitted from a cathode strike the phosphor; the current returns through a transparent conductive coating on the envelope. The phosphor layer emits light through the transparent face of the envelope. The system has a power supply providing at least five thousand volts to the light emitting device, and the electrons transiting from cathode to anode are essentially unfocused. Additional circuits allow triac-type dimmers to control the light level.[6] Lights produced so far have a color rendering index of 85. The energy consumption can be 70% less than that of a standard incandescent light bulb. Lifetimes can be as long as 10,000 hours, i.e. up to five times longer than that of an incandescent light bulb.[7]

Unlike fluorescent lamps, which produce light through the electrical excitation of mercury vapor, ESL lamps do not use mercury.[8] The first commercially available ESL product was a reflector bulb.

Drawbacks include a slightly larger-than-normal base and – as with compact fluorescent lamps – when switched on, a slight delay before illumination begins.[9]

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