Thermionic Emission

Thermionic emission is defined as the electron emission caused by a sufficiently high level of thermal energy. When a metal is heated sufficiently, the thermal energy supplied to the free electrons causes the emission of electrons from the metal surface. This occurs because the thermal energy given to the carrier overcomes the work function of the material. At average room temperature, the energy possessed by free electrons in a metal is insufficient to initiate thermionic emission.

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