RF characteristics of the APS storage ring isolation valve

The RF impedance of the sector isolation valve of the APS storage ring system was measured by the wire method with a synthetic pulse technique. The coupling impedance as well as the energy loss of the isolation valve with and without an RF liner or screen, and the flange gap of the various sizes was calculated from the measurements. There appear to be resonances at certain frequencies in the absence of an RF liner that might cause an unacceptably large coupling impedance. Data with various sizes of the flange gap show that a good RF contact around any flange is necessary. The results also are compared with computer simulation from MAFIA. The measured impedance due to the RF liner alone is within 0.2% of the total APS impedance budget