Space charge resonance effects in strong-focusing channels for charged particle transport

INstability of beam ''envelopes'' is considered to increase beam intensity in linear accelerators and transport channels. ''Nonlinear envelope resonances'', when the beam emittance growth will be their consequence, can occur in the region with μ0<90 deg (μ0 is the superposition of the particle transverse oscillation phase in the accelerating-focusing channel). The results of numerical simulation of beam dynamics by the ''large'' particle method are presented. It is shown that ''nonlinear resonance of the beam envelope'' is due to the space charge collective effect with unharmonic dependence of density on time for dismatched beam and is not due the space charge nonlinearity or external effects. For separate particle ''nonlinear resonance of beam envelope'' is developed in combinational resonance due to the presence of space charge subharmonic of the external (focusing) force in the field