Adiabatic Capture of Charged Particles in Islands of Phase Space: a New Method for Multiturn Extraction

A new method for multi-turn extraction from a circular particle accelerator is presented. It is based on adiabatic capture of particles into islands of transverse phase space generated by non-linear resonances. By appropriate use of non-linear elements, such as sextupoles and octupoles, stable islands can be created at small amplitude. By inducing an appropriate slow variation of the linear tune, particles can be captured inside these islands. This allows the beam to be split into different smaller beamlets in the transverse phase space. These beamlets can be finally transported towards higher-amplitudes to prepare them for extraction, performed by means of kicker and septum magnets. Results of numerical simulations are presented and discussed.