CYCLIC ION ACCELERATOR WITH BENDING AND FOCUSING BY ELECTROSTATIC FIELD

At present cyclotron type accelerators are widely applied to heavy ions acceleration. Particles bending is made by magnetic field perpendicular to median plane. Ion orbits pass inside accelerating dees electrodes. The development and distribution of such accelerators is constrained, mainly, availability large-sized, heavy, power-intensive and expensive magnetic system. For example, at proton energy 12-16 MeV magnet weight makes about 200 t. This report is devoted to creation practical opportunity discussion of ion deviation and focusing electrostatic system in a cyclic accelerator. The cyclic accelerator scheme with electrostatic deflector is shown on fig. 1. Fig.1. The Accelerator Scheme. This deflector is made in a kind of flat capacity plates, located along ion beam trajectory inside dees. Figure 1 designates vacuum chamber, 2- ion source, 3- one of RF accelerating dees electrodes, connected by means of the rod 4 with RF generator output[1]. Two dees are shown on fig. 1, though the electrodes number can be more. It depends on accelerator purpose and chosen working mode. Deflector electrodes 5 are connected with DC source poles, so the potential difference between them creates centrifugal force for ions. The arrows show ion beam motion direction. The particle acceleration is carried out as in usual cyclotron. The main difficulty consists of determination of electrodes shape, which permits to give possibility to keep revolution constant frequency, necessary for of RF field constant frequency mode, on the one hand, and betatron oscillations stability (radial and vertical focusing), on the other hand [1]. Revolution radius of nonrelativistic particle with charge Z and energy W is defined by expression