Simulation of longitudinal beam manipulation during multi-turn injection in J-PARC RCS

In a high intensity proton synchrotron the longitudinal beam emittance should be controlled to alleviate space charge effects at the injection. At the rapid cycling synchrotron in J-PARC our goal is to obtain and keep a high bunching factor during and after multi-turn injection. We have investigated the dependence of the bunching factor on second harmonic rf content, momentum offset, and second harmonic phase sweep. We found an optimum condition of the combination of these longitudinal rf manipulations that results in a flat bunch shape after injection.