This invention relates to a method of packetizing a charged particle beam (115). In accordance with the present invention, the first outer electrode (310), a second outer electrode (320), a first outer electrode (310) as viewed in the beam direction (101) and the second outer electrode (320 ) device having a disposed a ring-shaped center electrode (330) between (120) are provided, the particles pass through an electric field device (120), time-dependent voltage signal (610) There is applied to the center electrode (330). Time characteristic of the voltage signal (610) has a device (120) particles present is located in the dependence of the velocity change (510,910,920), the characteristics of this change in velocity (510,910,920) It is chosen to be approximately sawtooth wave as viewed in the beam direction (101).本発明は、荷電粒子ビーム(115)をパケット化する方法に関する。本発明によれば、第1の外側電極(310)と、第2の外側電極(320)と、ビーム方向(101)で見て第1の外側電極(310)と第2の外側電極(320)との間に配置されたリング状の中央電極(330)とを有する装置(120)が設けられており、粒子が装置(120)の電界を通過し、時間依存性の電圧信号(610)が中央電極(330)に印加される。電圧信号(610)の時間特性は、装置(120)内に存在する粒子が位置依存性の速度変化(510,910,920)を有し、この速度変化(510,910,920)の特性がビーム方向(101)で見て近似的に鋸歯波状となるように選定される。
