Thermionic emission

Thermionic emission (archaically known as the Edison effect) is the flow of electrons from a metal or metal oxide surface, caused by thermal vibrational energy overcoming the electrostatic forces holding electrons to the surface. The effect increases dramatically with increasing temperature (1000-3000 K), but is always present at temperatures above absolute zero. The science dealing with this phenomenon is thermionics. The charged particles are called thermions.

The vacuum diode tube

The British physicist John Ambrose Fleming, working for the British "Wireless Telegraphy" Company, discovered that the Edison Effect could be used to detect radio waves. Fleming went on to develop the two-element vacuum tube known as the diode, which he patented on November 16, 1904.

Related Topics:
John Ambrose Fleming - Vacuum tube - Diode - November 16 - 1904

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The thermionic diode can also be configured as a device that converts a heat difference to electric power directly without moving parts (a heat engine).

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