High Quality Content by WIKIPEDIA articles! The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field. The `resonant` cavity magnetron variant of the earlier magnetron tube was invented by John Randall and Harry Boot in 1940 at the University of Birmingham, England. The high power of pulses from the cavity magnetron made centimeter-band radar practical, with shorter wavelength radars allowing detection of smaller objects. The compact cavity magnetron tube drastically reduced the size of radar sets so that they could be installed in anti-submarine aircraft and escort ships. At present, cavity magnetrons are commonly used in microwave ovens and in various radar applications.