Multi-physics analysis of a 325 MHz bi-periodic on-axis coupled accelerating structure

Abstract

A 325-MHz bi-periodic on-axis coupled accelerating structure prototype which consists of two bi-periodic accelerating modules is under fabrication in the Institute of High Energy Physics, Beijing, dedicated to a 10-MeV/100 kW industrial linear electron accelerator. According to the beam dynamics study, the average power dissipated in the prototype cavity is about 19.1 kW. Effective cooling scheme is one of the most important issues in the high-power operation. This paper mainly deals with the RF, thermal and structural coupled analyses of the accelerating structure prototype with the help of the ANSYS code. The cooling scheme is optimized to minimize the temperature rise, displacement and von Mises stresses. The temperature and stress distributions in the steady state are presented. The maximum von Mises stress is much lower than the yield strength limit of the corresponding material. The frequency shift caused by the thermal expansion is calculated as well, which is within the scope of the tuning range. The coupled analyses based on the ANSYS software package are presented to design and optimize the cooling scheme of the accelerating structure. The von Mises stresses are much lower than the yield strength limit of the material. The calculation results indicate that our cooling scheme can deal with the dissipated RF power efficiently.