Space-Cheirge-Limiting Current of a Relativistic Electron Beam Propagating in a Rippled-Wall Waveguide

A Quid model is used to derive the space-charge-limiting current of a relativistic electron beam drifting in a rippled-wall cylindrical waveguide.It is found that an enhancement of the space-charge-liniiting current is found as long as optimum values of the ripple wavelength and amplitude are chosen.However,a very small ripple wavelength of the waveguide may reduce the space-charge-limiting current rapidly.The result should be of interest to the operation of backward-wave oscillators.