A method for controlling a radio-frequency plasma generator including a supply circuit with a switch controlled by at least one control pulse train, for applying an intermediate voltage at a control frequency on an output to which is connected a resonator for generating a spark between two electrodes when a high voltage level is applied to the output. The method receives first and second measurement signals respectively representative of the operation of a combustion engine and of the type of spark generated; and real-time adjusts, based on the received measurement signals, at least one parameter selected from at least the intermediate voltage level, the control frequency, and the duration of the control train, to promote branching of the spark generated.