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Two types of ARES cavities were tested in the TRISTAN accumulation ring in KEK. In this paper, results relating to the fundamental mode in the accelerating cavity are reported. The status of the cavity, including the detuning frequency under beam loading and the output power from the coupling cavity damper, was measured at different beam current and with various bunch patterns. Its behavior agrees well with the calculation based on a coupled resonator model.

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.

The coaxial (WX120D) antenna damper has been developed for damping the parasitic 0 and /spl pi/ modes of the KEKB ARES cavity. It is installed in the coupling cavity of the ARES. The damper consists of a disk-type coaxial ceramic window and a cross stub angle. The damper has a broadband RF property in order to absorb the RF power of the parasitic modes. The cross angle is utilized for supplying the cooling water to the antenna. The damper was designed by using a computer simulation code without a cold model test. Finally the properties of the damper has been confirmed by the high-power and the beam test for the ARES cavity.