- a two-element vacuum tube in which the flow of electrons is under the influence of an external magnetic field, used to generate extremely short radio waves.
- an electronic valve with two coaxial electrodes used with an applied magnetic field to generate high-power microwave oscillations, esp for use in radar
- An electron tube that produces coherent microwave radiation. Magnetrons are diodes in which the electrons traveling to the anode are set in spiraling paths by a magnetic field created by permanent magnets. The circular component of the electrons’ motion causes microwave-frequency oscillations in the voltage induced in resonating cavities built into the anode, which is connected to an antenna that emits the microwaves. Magnetrons are used in radar and in microwave ovens.