The output power of generation in a chain of unidirectionally coupled low-voltage vircators upon variation in controlling parameters of a system is studied. It is shown that at a certain set of controlling parameters, the output power of the generator chain grows sharply. Physical processes occurring in the system are analyzed by plotting space-time diagrams of the motion of charged particles of the electron flow with a virtual cathode. The obtained results are in good agreement with the data from a previous experimental study on signal amplification in a low-voltage vircator.