Abstract
To develop the high power proton linear accelerator for the Accelerator Driven System (ADS) program, the preliminary design of the Pi mode accelerating structure (PIMS) has been carried out. It is estimated that PIMS would heat up to 80 °C for low duty cycle (0.1%) without water-cooling, which is not acceptable, thus water-cooling is demanded. The structure stability for the high duty cycle or even for CW operation is crucially important for the ADS application. Therefore, thermal analysis with water-cooling for a high duty accelerator in our ADS research is performed to control the frequency shift caused by a temperature rise.