Magnetron
From HvWiki
Simulation
Particle-in-cell simulation of a magnetron starting up. There is a magnetic field axially into the screen. There is a radial electric field from the anode slow wave structure (outside part) to the cathode (middle part). Electrons (red dots) are pulled from the cathode and rotate around due to the crossed electric and magnetic fields (from Lorentz force equation). The colors in the background are the azimuthal electric field.
In a magnetron electron kinetic energy is converted to energy in an RF field.
As the electron hub rotates random noise and instabilities lead to azimuthal density variations and thus electric field perturbations. Once this electric field begins interacting with the slow wave structure (on the anode) the feedback between this and the rotating electrons will lead to the formation of spokes. There are some velocity matching conditions that must be met for the rotation electrons to be in phase with the RF mode that is in the slow wave structure that I dont feel like explaining. There are 6 vanes and 3 spokes, this is Pi-mode, the electric field changes by 180 degrees in every cavity.
Safety
Some magnetrons have ceramic insulators containing beryllium oxide. These ceramics often appear somewhat pink or purple-colored. Note that beryllium oxide is white so relying on the color to identify its presence would be unwise. Beryllium is a serious chemical hazard if crushed and inhaled, or otherwise ingested. Beryllium is listed as a confirmed human carcinogen by the IARC; therefore, broken ceramic insulators or magnetrons should not be directly handled. [1]
