Novel Method for Multi-turn Extraction: trapping charged Particles in Islands of Phase Space

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