Longitudinal dynamics of RF-bunched and electron-cooled ion beam at the CSRe

Abstract: The longitudinal dynamics of RF-bunched and electron cooled ion beams have been studied at the experimental cooler storage ring (CSRe), at IMP Lanzhou. By RF-bunching the ion beam at the 50th and 100th harmonic of the revolution frequency, the longitudinal momentum spread and the bunch length of the 22Ne10+ ion beam with an energy of 70 MeV/u were measured by the new resonant Schottky pick-up and the capacitive pick-up, respectively. A minimum momentum spread of Δp/p=1.6×10−5 has been reached with less than 107 ions stored in the ring. By using the harmonic potential extracted from the Taylor expansion and the real sinusoidal potential of the bucket, the trend of momentum spread and synchrotron frequency as well as the bunch length as a function of beam current can be interpreted very well. According to this experiment, the RF-buncher is suitable for upcoming experiments on laser cooling of relativistic heavy ion beams at the CSRe.