A method for packetizing a beam-charged particle, in which the particles pass through an electric field in a device is provided. The device includes an annular shaped central electrode which, in the direction of the beam, is arranged between a first outer electrode and a second outer electrode. A time-dependent electric voltage signal is applied to the central electrode, the temporal course thereof being selected such that particles inside the device undergo a position-dependent speed modification. The course of the speed modification is approximately sawtooth-shaped in the direction of the beam. An associated device is also provided.