Design and Simulation of T-Shaped Buncher for High Power Ridgetron Accelerator

In this paper, a T-type buncher for a ridgetron accelerator is designed to further enhance the beam capture efficiency of a high-power ridgetron irradiation accelerator and reduce beam loss in the accelerator system. By incorporating a branch, the T-shaped buncher can reduce the required space compared with conventional coaxial bunchers at the same operating frequency. The physical design and electromagnetic field simulation of the T-type buncher were carried out using the CST frequency-domain solver and eigenmode solver. Subsequently, the bunching performance and its impact on beam transport in the ridgetron accelerator were further evaluated using the PIC solver. The results show that, within an input power range of 120–200 W, a 5 ns input pulse can be compressed to less than 0.6 ns, while the energy spread is maintained between 22% and 26%. At an input power of 140 W, the application of the buncher reduces beam loss after the first deflection by approximately 40%. When a 5 ns electron bunch is compressed to 2 ns (non-FWHM), the beam current increases by a factor of approximately 3.13 compared with the injection without the buncher. These results clearly demonstrate the effectiveness of the T-shaped buncher in improving beam capture efficiency and overall accelerator performance, providing a valuable reference for further power enhancement of ridgetron accelerators.