3. Gyrotrons

3.1 Gyrotron operating principle

Like magnetrons, gyrotrons are oscillators (they hang on noise), except that they are used at much higher frequencies (between 50 and 200 GHz, sometimes below, increasingly above). They deliver fantastic power (up to 2 MW CW) and are reserved for very specific applications, some of which are important enough to be presented here.

Developed around 1958 in the USA and the USSR, their operation is complex, and we'll only give a simplified overview. Electrons are generated by an impregnated cathode, and accelerated by a gun. They...