Field emission gun
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A field emission gun is a type of electron gun in which a sharply pointed Müller-type emitter is held at several kilovolts negative potential relative to a nearby electrode, so that there is sufficien
Schottky-emitter electron source of an Electron microscope
Thermionic emission
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Thermionic emission is the liberation of charged particles from a hot electrode whose thermal energy gives some particles enough kinetic energy to escape the material's surface. The particles, sometim
Field emission gun
…are either of cold-cathode type, usually made of single crystal tungsten sharpened to a tip radius of about 100 nm, or of the Schottky type, in which thermionic emission is enhanced by barrier lowering in the presence of a high electric field. Schottky emitters are made by coating a tungsten tip with a layer of zirconium…
Closeup of the filament in a low pressure mercury gas-discharge lamp showing white thermionic emission mix coating on the central portion of the coil. Typically made of a mixture of barium, strontium and calcium oxides, the coating is sputtered away through normal use, eventually resulting in lamp failure.
One Edison effect bulb consisted of an evacuated bulb with an externally-wired electrode such as a metal plate in this example (variants used platinum foil or extra wire instead) isolated from the carbon filament (hairpin-shaped in this example).