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.

History

It was initially reported in 1873 by Guthrie in Britain. While doing work on charged objects, Professor Guthrie discovered that a red-hot iron sphere with a negative charge would lose its charge (discharging the extra electrons into the vacuum). He also found that this did not happen if the sphere had a positive charge. Other early contributors included Hittorf (1869-1883), Goldstein (1885), and Elster and Geitel (1882-1889).

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Owen Richardson worked with thermionic emission and received a Nobel prize in 1928 "for his work on the thermionic phenomenon

Related Topics:
Owen Richardson - Nobel prize

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and especially for the discovery of the law named after him".

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