Design and optimization of a compact 2.45 GHz ECR ion source for BNCT applications

The 2.45 GHz electron cyclotron resonance ion source (ECRIS) is highly effective for generating high-intensity H⁺ ion beams. To meet the precision requirements of medical applications such as boron neutron capture therapy (BNCT), compact and adjustable ECR ion sources are essential. This study presents the design, assembly, and preliminary testing of a high-performance, compact ECR ion source. Using a three-dimensional model, we optimized the plasma chamber geometry to improve spatial efficiency and beam quality, achieving an electron density of approximately 10¹⁸ m^-3 and H⁺ purity over 90%. Initial experiments confirmed stable and reliable operation, with a maximum extraction current of 40 mA. By integrating simulations and experimental analysis, we systematically examined the effects of working gas pressure and microwave power on ion source performance. The optimized configuration demonstrated superior stability and beam intensity compared to conventional designs. The Accelerator-Based BNCT (AB-BNCT) system employing this ion source has completed assembly and preliminary testing, showing excellent operational performance.