Design and optimization of a 2 MeV X-band side-coupled accelerating structure

Purpose: As the development of smaller accelerators technique, an X-band bi-period side-coupled accelerating structure has been designed for medical use. Methods: The structure’s working frequency is 9.3 GHz. π/ 2 mode is chosen for the structure’s stability. There are 11 accelerating cells and 10 coupling cells, the first 5 of the accelerating cells work as non-light velocity part (β of the electron from 0.17 to 0.94), while the other 6 work as light velocity part. After CST simulation, the coupling constant between accelerating cells and coupling cells is 5%, and efficient shunt impedance is 142 MΩ / m. To feed power into the structure, a coupler is designed in the middle of the structure and the coupling coefficient is 1.4. Results: After optimization, the particle’s capture efficiency is more than 30%, the particle energy is 2 MeV and the peak current is 60 mA, with the magnetron’s input power being 0.32 MW. Conclusion: X-band side-coupled accelerator efficiency is high and is a more optimized design. This design is very meaningful for the development of smaller accelerators technique. © 2017, Institute of High Energy Physics, Chinese Academy of Sciences; China Nuclear Electronics and Nuclear Detection Society and Springer Science+Business Media Singapore.