FLASH radiotherapy (FLASH-RT) demonstrates the potential to maintain tumor control while reducing normal tissue toxicity through ultra-high dose rates. This paper presents a novel compact X-band (9.3 GHz) accelerating system designed for FLASH-RT applications. The core innovation is a dual-structure common-source architecture: the first structure provides a fixed 6 MeV energy gain, while the second enables independent continuous energy adjustment from 0 to 6 MeV via a tunable microwave network. This design allows a single klystron to drive both structures without mutual interference during energy adjustment. The system length is only approximately 1 meter. The design process integrates radio frequency (RF) simulation and beam dynamics simulation in a coupled manner, with particular focus on the bunching section optimization. This compact system provides a high-performance accelerator solution for next-generation FLASH radiotherapy, especially for intraoperative applications requiring rapid energy adjustment.

The dual-mode microwave structure is receiving increasing attention and research. In the application of dual-mode structures, it is necessary to solve the problem feeding microwave power at different frequencies. One method is to use complex waveguide components, such as first and second harmonic photocathode bimodal gun, which consists of the assembly of the directional coupler and the mode launcher. The structure combines the S-band and C-band power into a waveguide and feeds them into the dual-mode electronic gun. Another method is to use ridge waveguide to achieve selectable transmission or blocking of specific frequency. Currently, the ridge waveguide has been applied to dual-mode deflecting structure. This paper presents a X-band bandpass filter has been engineered to achieve a power reflection level of less than -30 dB at 12 GHz and a power transmission level of less than -40 dB at 24 GHz.

A 714 MHz proton linac was designed for medical applications. The linac aims for both sychrotrons and S-band linacs. Proton beams can be accelerated to 8 MeV with high transmission.

A new 425 MHz injector has been designed for proton and helium therapy facility. The LINAC consisted of a 3.0 m length RFQ and a 2.8 m length IH-DTL, which was designed to accelerate H2+ and He2+ beams to 8 MeV/u. The beam dynamics of the linac were designed based on comprehensive 3D electromagnetic field simulations, followed by particle tracking to optimize beam quality and transmission efficiency. Multi-physics analysis investigated thermal effects on cavity resonant frequencies.

Proton therapy has attracted increasing attention because of its favorable dose distribution enabled by its Bragg-peak behavior. Motivated by the proton therapy facility project at Shanghai Synchrotron Radiation Facility (SSRF), a 2.45 GHz ECR ion source has been designed and fabricated. This paper presents the conceptual design of the prototype, together with simulation results of the magnetic field configuration, the ridged waveguide and the beam extraction.