Vacuum tube with an electron beam that is current and velocity-modulated

TLDR: In this paper, 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.

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. The phase-shift circuit is connected between the first cavity and the resonant structure or between the second cavity and the resonant structure. A resonant slow-wave circuit is included in the electron-permeable or in an electrically conductive support structure for the grid.