APS SR flexible bellows shield performance

The Advanced Photon Source (APS) storage ring (SR) consists of long rigid vacuum chambers connected by flexible formed bellows components. These SR bellows and additional diagnostic chambers are designed with leaf spring beryllium-copper (Be-Cu) alloy contact fingers that insert into mating rigid sleeves to function as electromagnetic shields. The shields protect the bellows convolutions from particle beam image currents and RF energy and reduce beam-induced RF resonances in the diagnostics chambers. The beam aperture of the shields is approximately the same as that of the beam chambers so that the beam impedance of the SR is minimized. The bellows shields systems´ thermal performance has been tested and is monitored during APS SR beam operations. Testing included infrared radiometer camera imaging and thermocouple instrumentation of the rigid sleeve. Direct results indicate that the liners perform well under all stored beam fill loadings through and including 100-mA, 8-bunch operations. Maximum temperatures of the bellows liner systems are typically 35-500 Celsius during standard 100 mAmp stored beam fills and 50-700 Celsius during fills, producing both maximum peak and total current simultaneously. The indirect observations of ring vacuum levels support the temperature data