Novel method for multiturn extraction: trapping charged particles in islands of phase space

A novel method for multiturn extraction from a circular particle accelerator is presented, based on trapping particles into islands of phase space generated by nonlinear resonances. By appropriate use of sextupoles and octupoles, stable islands can be created at small amplitude in phase space. By varying the linear tune, particles can be trapped inside these islands and then transported towards higher amplitudes for extraction. Results of numerical simulations are discussed.