Production of Beams with High Line-Density by Azimuthal Combination of Bunches in a Synchrotron

Simultaneous acceleration of several beams in the same machine by several RF fields of slightly different frequencies was already considered a long time ago1,2). As they rotate at different frequencies, the bunches will periodically coincide in azimuth, thus producing beams of high local line density. Bunches rotating at different frequencies can be produced either outside the machine (e. g. in the injector) or even inside by appropriate modulation of the RF cavities. These techniques will be used in the p-p¿ project at CERN. A high line-density proton beam, necessary for antiproton production, is obtained in the CPS by azimuthal combination, either at the injection or at the ejection level. On the other hand, the antiproton bunches in the SPS must be azimuthally combined before storage in order to achieve the design luminosity. Computer simulation and RF manipulations of these procedures, as well as experimental results already obtained at the CPS, are presented.