A magnetron is a two-
electrode valve in which the flow of
electrons from a large central
cathode to a
cylindrical anode is controlled by
crossed electric and
magnetic fields; the electrons
gyrate in the
axial magnetic field, their energy being
collected in a series of
slot resonators in the face of the anode.
Magnetrons, used mainly as oscillators, can produce pulsed output at microwave frequencies, with high peak power ratings. Used as microwave and RADAR transmitters, and microwave ovens.