Improved temperature regulation and corrosion protection of APS linac RF components

Water from individual closed-loop deionized (DI) water systems is used to regulate the temperature of high-power RF components at the Advanced Photon Source (APS) S-Band linac. The RF components are made of oxygen-free high-conductivity copper and respond quickly to temperature, resulting in changes in the beam energy when the temperature is poorly 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. In the long term, depletion of copper from the water circuits is a very real and serious concern, thus steps are being taken to reduce corrosion. Temperature regulation philosophy and equipment are discussed and numerical results are presented. Steps to decrease copper corrosion are also discussed