Magnetron

A magnetron, more precisely a cavity magnetron, is a high power vacuum tube originally used in early radar systems and later also in microwave ovens and linear particle accelerators, generating microwaves through the interaction of a stream of electrons with a magnetic field as they move past a series of cavity resonators. Unlike a klystron or a traveling wave tube, a magnetron cannot amplify an existing microwave signal; it works only as an oscillator, generating a microwave signal directly from direct current electricity. In 1940, John Randall and Harry Boot at the University of Birmingham developed an improved cavity magnetron whose first working example produced hundreds of watts at a 10 centimeter wavelength, an unprecedented result at the time that rapidly advanced radar capability during the Second World War. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/