Extended interaction device comprising coaxial resonant cavities and multiple electron beams

A millimeter-wave extended interaction device, comprising:

• a device body;
• resonant cavities;
• electron beam tunnels;
• an output waveguide;
• and
• a coupling hole;
• wherein
• the device body comprises a shell and a core, and an annular coupling channel is disposed between the shell and the core;
• the resonant cavities are a set of ring-shaped cavities with a radial height of 2 /5 λ to 3/5 λ, parallel and equally spaced around an axis of the core;
• the electron beam tunnels are arranged at equal radian intervals and parallel to the axis of the core, each electron beam tunnel communicating with the ring-shaped resonant cavities and passing through two end walls of the core;
• the output waveguide is disposed in a middle of the shell and communicates with the annular coupling channel through a coupling hole;
• and
• the core and an inner surface of the shell are sealed and fixed, and the output waveguide and the shell are sealed and fixed.