Space charge wave revision to the electron beam bunching caused by radiation wave in klystron

Using a relatively strict method, the formulas of the harmonic current of the modulated electron beam in the klystron and Cherenkov devices were derived in the relativistic regime,in which the effect of the space charge wave was taken into account. The role of the space charge wave is that it makes bunching reduce at small signal, but it makes bunching enhance at large signal.