Abstract Circular Beam Scanning of Large Targets

Circular sweep of the beam over a large target for making a uniform irradiation zone is suggested. The scanning pattern is an untwisted spiral if the beam is z-uniform or a collection of concentric circles if the beam consists of bunches of particles. Deflection voltage is provided by RF cavities with orthogonal transverse fields shifted in time by 7d2. The amplitude of deflection voltage as a function of time and the optimal beam scan frequency with respect o RF frequency of accelerator are given.