Design and Numerical Simulation of a SARA-Based RF Accelerator Using the $\mathrm{TE}_{112}$ Mode

Abstract: Charged particle accelerators play a pivotal role in scientific research, industry, and medical applications. Among them, radiofrequency (RF) accelerators offer a promising approach for achieving high-energy particle acceleration in compact systems. This study presents the design and numerical simulation of a microwave-driven electron accelerator based on the Spatial Autoresonant Acceleration (SARA) mechanism. The proposed system consists of a cylindrical resonant cavity excited in the TE$_{112}$ mode, influenced by a tailored magnetostatic field generated by a set of external coils. The electromagnetic field distribution, magnetostatic configuration, and electron dynamics were simulated using COMSOL Multiphysics. The results validate the feasibility of accelerating electrons to energies close to 200~keV with a 1~kW microwave source, demonstrating their capability for X-ray generation through Bremsstrahlung radiation. Additionally, the study provides optimized design parameters for practical implementation. The high-quality factor $(Q\sim25000)$ of the resonant cavity ensures efficient energy storage but necessitates precise frequency control to maintain resonance conditions. The findings underscore the potential of SARA-based accelerators for compact X-ray sources, with applications in medical imaging, security screening, and materials analysis.