The results of analytical estimation and numerical simulation of the interaction of the inhomogeneous isothermal plasma with a modulated electron beam are presented. The formation of a fuzzy jump of the plasma density in the late phase of the interaction in a region, where the local plasma resonance point initially existed, is demonstrated. The jump is moving to the dense plasma, when the current density amplitude of the beam is large. K e y w o r d s: modulated electron beam, local plasma resonance region, ponderomotive force, inhomogeneous plasma