Design Of A High-Power Test Cavity For The Atf Damping Ring

INTRODUCTION A HOM damped cavity for the ATF damping ring (DR) [1] is under development at KEK. This cavity is capable of avoiding coupled-bunch instabilities driven by higher order modes (HOMs). In order to damp the Q's of HOMs the cavity is equipped with four waveguide ports, the cutoff frequency of which is higher (f c 887.3 MHz) than the accelerating frequency. Additional HOM damping is provided by HOM absorbers in the beam pipes next to the cavity [2]. The basic design and results of low-power measurements are described in refs. [3] and [4], respectively. The overall design of the RF-system is presented in an accompanying paper [5]. In order to demonstrate the feasibility of high-power operation, the construction of a high-power test cavity is under way. The design parameters of the test cavity are shown in Table 1. Although a total wall loss of 17.4 kW is conservative, special care has been taken concerning the cooling design, because c