IMPROVED TEMPERATURE REGULATION OF APS LINAC RF COMPONENTS*

The temperature of the APS S-Band linac's high-power rf components is regulated by water from individual closed-loop deionized (DI) water systems. The rf components are all made of oxygen-free high-conductivity copper and respond quickly to temperature changes. The SLED cavities are especially temperature-sensitive and cause beam energy instabilities when the temperature is not well regulated. Temperature regulation better than ± 0.1 °F is required to achieve good energy stability. Improvements in the closed-loop water systems have enabled us to achieve a regulation of ± 0.05 °F over long periods. Regulation philosophy and equipment are discussed and numerical results are presented.