Electron-beam defocusing due to high-intensity RF fields

The electric fields associated with a "slow" electro-magnetic wave propagating along an electron beam will modulate this beam; the axial component of field will produce the usual "bunching," while the radial component will cause periodic perturbations in the radius of such an electron beam. This paper presents the results of analytical and experimental studies in an attempt to explain certain features of this defocusing effect of intense RF fields on the beam in a traveling-wave tube. In particular the effect of cathode flux on the RF defocusing of a beam in Brillouin flow is treated.