Abstract: A folded waveguide gyrotron-traveling-wave-amplifier comprises: an electron gun for transmitting an axis-encircling beam of electrons with large transverse energy along a first path having an axis; an RF source for producing and applying in a second path an RF input millimeter wave signal having a bandwidth in a preselected frequency domain and having a transverse electric field; a source for generating a solenoid magnetic field parallel to the axis along the first path; a beam collector; and an interaction circuit such as an H-plane bend serpentine waveguide positioned within the solenoid magnetic field and having a narrow wall containing a beam tunnel hole for passing the axis-encircling beam of electrons therethrough to the beam collector, an output end, and an input end for receiving and passing the RF input millimeter wave signal through the H-plane bend serpentine waveguide to the output end to modulate the axis-encircling electron beam, the modulated axis-encircling electron beam amplifying the RF inpu

Abstract: The present invention is a coupled cavity gyrotron-traveling-wave-tube amplifier which produces highly efficient, broad band millimeter wave radiation. The present invention comprises an electron gun, a double ridged coupled cavity interaction circuit and a beam collector. In operation the gun injects a gyrating electron beam through a beam tunnel of a side wall of the coupled cavity. When the electron beam phase is synchronized with the rf phase of the transverse electric mode in the coupled cavity circuit, the electron beam is modulated and amplifies the rf input signal through the negative mass instability called electron cyclontron instability. The coupled cavity design of the interaction circuit effctively slows the rf-wave velocity, allowing amplification of the rf- wave over a broad band. This t ype of broad band microwave energy is highly useful in radar, communications and jamming technology.