On the use of metamaterials for increasing of output power of multibeam klystrons

At restricted anode voltage output power of multibeam klystron is limited by amount of beams. It depends on the diameter of ferrules in microwave cavities which is limited by a half of wavelength. Special design of the cavity filled with artificial metamaterial increases phase velocity and wavelength inside the gap which makes possible to increase significantly the diameter of ferrules, total current and output power.