Abstract: An inductive output tube, e.g., a KLYSTRODE, or a klystron, has a substantially hollow electron beam traversing a resonant cavity excited to the TM.sub.0x0 mode, where x is greater than 1.

Abstract: The frequency of an AC signal is multiplied by a factor N, where N is an integer greater than one, by an electron tube including a cathode for emitting an electron beam and a grid including N segments in proximity to the cathode. The grid is biased and coupled to the signal so the beam is formed as N groups of electron bunches during each cycle of the signal. Each segment accelerates one group of bunches for a duration of about 1/N th of each cycle of the signal. Different groups of bunches associated with the different segments are accelerated at phases displaced from each other during each cycle of the signal. In response to the N groups of bunches an output signal having a frequency N times that of the signal is derived.

Abstract: A super-power, high voltage klystron includes an output cavity operating in the TM.sub.01x mode, where x is greater than zero.

Abstract: A high-frequency amplifier tube includes a grid that responds to an r.f. input signal to current modulate a linear electron beam derived from a cathode. A resonant structure establishes an electric field in a region between the grid and cathode. First and second resonant cavities downstream of the grid in the named order are coupled to the modulated electron beam. The first cavity responds to the r.f. signal to velocity modulate the current-modulated beam. The second cavity is coupled to the current- and velocity-modulated beam for deriving an output signal. An AC connection from a source of the input signal is established to transformer coupling in the first cavity. A phase-shift circuit adjusts the relative phase of the modulation on the beam as it passes through the first cavity and the phase of the r.f. signal as coupled to the first cavity so that fields induced in the cavity by the modulated beam are optimally phased with respect to fields established in the first cavity by the transformer coupling.

Abstract: To suppress spurious oscillations in a helix-type traveling wave tube (TWT), frequency-sensitive loading is produced by a lossy resonant circuit attached to a dielectric support and coupled to the fields of the interaction circuit. The lossy circuit is resonant near the band-edge frequency. It may be a section of delay line with reflective terminations. In one embodiment, it is a metallized pattern on a dielectric rod used to support the helix.

Abstract: A grid-controlled electron source comprises an apertured grid spaced in front of a thermionic cathode. Areas of the cathode directly behind the grid conductors are made non-emissive by a bonded surface layer of non-emissive material such as zirconium. On porous metal cathodes impregnated with active emitting material the metal surface may be sealed with a dense layer of inactive metal under the non-emissive layer to prevent chemical reaction of the latter with the emitting material.Methods of depositing the surface layers in the desired pattern include coating the cathode's entire large-scale surface contour, followed by machining small concave dimples into the surface, thereby removing the non-emissive layer from the dimpled surfaces from which small beamlets of electrons are focused between the grid conductors without grid interception.Another method is to mask the desired non-emissive areas with an apertured mask having solid elements registered with the desired positions of the grid conductors.