Broadband synchrotron cavity for COSY with minimum size based on VitroPerm

A cavity design that deviates from conventional rules of RF engineering is presented. Preliminary studies in collaboration with SATURNE and TERA were carried out to employ the amorphous material VitroVac for a cavity with reduced size. The idea to use a nano-crystalline material instead of an amorphous one was stimulated by KEK where metglass is applied. The analysis led to the magnetic material VitroPerm 500F, resulting in a reduced cavity size as compared to the existing one. Now, new space has become available in COSY for additional equipment used for a polarized proton beam. The cavity is optimized for operation at the Cooler Synchrotron COSY. The frequency ranges from 400 kHz to 2 MHz without any tuning device. No gap-capacitors and no cooling discs are necessary. The VitroPerm is directly water cooled. Together with the fundamental higher harmonics (2nd or 4th), adjusted in real time in amplitude and phase, it can be applied to bunch or to accelerate with non-sinusoidal voltages