Cool-stacking injection and damping of a transverse ion-beam instability at the HIMAC synchrotron

High-density ion beams obtained by electron cooling will be used for medical and other applications at HIMAC. Cool-stacking injection was carried out with Ar18+ions at 6MeV/u to increase the intensity to a limit, which was determined by instabilities and by the ion lifetime. The maximum ion stack intensity was 2emA, above which fast-ion losses occurred simultaneously with vertical coherent oscillations. The instability depends on the working point, the ion stack density and secondary ions trapped in the cooler. The instability was damped by reducing the stacked ion density with transverse RF-excitation, and/or by clearing the secondary particles.