A design by Westinghouse from 1941 but published post war.
Space charge correction in velocity modulated oscillator.
In short-wave generators of the velocity-modulating type, the concentration of electrons in the space, following the first resonator, tends to create space-charges which adversely, affect the operation of the device.
The electrons in the arrangement shown are passed from the bunching resonator R to the second or load resonator R1 through a crescent-shaped channel under the control of the transverse field from a magnet M.
The RF field between the narrow walls of the centre portion of the resonator R imposes on the electron beam a slight lateral vibration, in addition to producing the usual bunching effect. This side-to-side deflection shifts the radius of curvature of the paths taken by the electrons under the influence of the magnet M, so that those swung to the right, and leaving the resonator slightly behind time, follow the path D, which is shorter than the normal curve C.
Similarly, when the beam is swung to the left, those emerging first take the longer path E. The correct bunching of the stream is thus preserved until it reaches the delivery or load resonator R1 whilst undue overcrowding in transit is avoided.
Westinghouse Electric International Co. Convention date (USA) Aug. 20th, 1941. No. 578588.