Magnetroner

Magnetroner are vacuum tubes that generate microwaves by the magnetron principle. In English the singular is magnetron and the plural magnetrons; magnetroner is the form used in some Scandinavian languages.

A magnetron consists of a heated cathode inside a hollow, cylindrical anode with multiple resonant cavities around its circumference. A strong magnetic field oriented perpendicular to the tube’s axis causes electrons emitted by the cathode to travel in spiraling paths. When these electrons interact with the resonant cavities, microwave energy is produced and can be extracted through an output coupling port. The device requires a high-voltage supply and a magnetic field to sustain operation, and it operates as a self-oscillating megahertz-to-gigahertz source.

Two main types are used in practice: the cavity magnetron, which relies on stationary cavities to set the oscillation frequency, and traveling-wave magnetrons, which use a helical interaction structure for broader frequency control. Operating frequencies for magnetrons typically lie in the 0.9 to 3 gigahertz range, with 2.45 gigahertz being common for consumer microwave ovens and many industrial applications. Other frequencies are used in radar and specialized heating or plasma processes.

Applications include microwave ovens, radar transmitters, industrial drying and heating, and some medical and research uses. Magnetron technology has faced competition from solid-state devices in some sectors, but it remains valued for delivering high power at relatively low cost and with robust simplicity. Safety considerations include shielding to prevent exposure to microwave radiation and strict high-voltage and vacuum-system precautions.