HOM characteristics of the ARES cavity

The ARES (Accelerator Resonantly coupled with an Energy Storage) cavity, which consists of three cells, has been developed for the KEK B-Factory, and two types of the ARES cavity have been constructed for the beam test. Both the types were installed in the KEK TRISTAN Accumulation Ring and beam-tested. The accelerating cell of the ARES has a HOM-damped structure to lower the impedance of HOMs in order to store a high current beam. The spectra excited by the beam (single bunch, 100 mA) were measured for both the cavities with scanning of the resonant frequency. Basically these results are consistent with those of calculations. The HOMs appear to be damped as expected. But the actual spectra for three cells are more complicated than only the accelerating cell. During this experiment, however, any beam instabilities due to the impedance of the cavities were not observed. This paper describes only the "ARES95"-one of the two types of the ARES.