Disk and Washer Structure for an Electron Storage Ring

The result is given of test cavity measurements of a 500 MHz disk and washer structure which will be used for the TRISTAN electron storage ring, where the shunt impedance is required to be higher than 35 MΩ/m. While the calculated shunt impedance is 44.8 MΩ/m, the measurement indicates that 40.0 MΩ/m is attainable with a single radial stem for the washer support and 35.8 MΩ/m with a 2-longitudinal-stem support.