General Science

  • noun an electronic valve used to generate microwaves


  • A microwave tube utilized to generate oscillations in the microwave range of the electromagnetic spectrum. A magnetron usually incorporates a heated cathode, consisting of a hollow cylinder, which is surrounded concentrically by a cylindrical anode with multiple resonant cavities, all of which is contained within a vacuum enclosure. The path of electrons leaving the cathode is influenced by surrounding orthogonal electric and magnetic fields, the latter produced by one or more permanent magnets or electromagnets. In this manner, the electron path to the anode is not straight, but is rather an expanding spiraling orbit, with electrons eventually reaching the anode. The geometry and size of the cavities determine the frequency of the oscillations, and output may be taken, for instance, through a coupled waveguide or a loop to a coaxial line. A magnetron may be used in a pulsed mode, as occurs in radar applications, or its output may be continuous, as is the case when utilized for heating in microwave ovens. Also called magnetron oscillator.