Characteristics of electron-cooled bunched beams predicted by a simulation

Characteristics of electron-cooled bunched ion beams have been studied using the particle-tracking simulation in which the space-charge force and the force induced through the transverse broadband impedance are taken into account. The beams become space-charge dominated during the bunching of coasting beams. The simulation results show that the beams meet the transverse instability which can be cured by a transverse feedback, and the seed of the instability is the toroid field of the electron-cooling section. The following RF-wave-form distortion phenomena can be seen at stable or stabilized bunched beams. As well as the longitudinal line density becomes parabolic-liked, the nearer to the bunch center, the larger the beam size is. The bunch motion is a quasi-elastic motion instead of the synchrotron oscillation in the longitudinal direction, and is a dipole-mode coherent oscillation with the head-tail-mode number 1 in the horizontal direction