A high-power multiple-harmonic acceleration system for proton- and heavy-ion synchrotrons

A novel acceleration system for the (simultaneous) application of higher or multiple-harmonics in proton or heavy-ion synchrotrons has been developed for various uses, e.g. the passage of the transition point, applying stochastic cooling on a bunched beam, or for other longitudinal beam manipulations as bunch stretching or compression. The system consists of a coaxial cavity filled with the ferritic amorphous metal VITROVAC of VAC, Hanau, in lieu of the conventional ceramic materials. In its current configuration, it can support a frequency range of 0.2-8 MHz. Amplifier modules for both 10 and 50 kW are available to produce gap voltages in the kV-range. By means of digital synthesis techniques, virtually arbitrary voltage waveforms with harmonic admixtures up to fourth order can routinely be generated at the cavity gap. As illuminating examples we, achieved at high precision a flat-top wave form suitable, e.g. for the transition crossing, a linearized force law at the center of the bucket, and a fourth-order flattened bucket for bunched-beam cooling. The compact cavity system should be well suited for any synchrotron operating in this frequency range. Actual installation of such a system is projected for the medium energy device COSY Julich, and the therapy-oriented ring TERA