Design and optimization analysis of key parameters for a compact ion source for BNCT

The 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is widely recognized as an effective device for producing high-intensity H⁺, H₂⁺, and H₃⁺ beams. In medical cyclotron applications, ion sources are required to be compact and highly adjustable. A compact design not only reduces the equipment size, facilitating integration and installation, but also enhances system stability and reliability. High precision in adjustment ensures the quality and stability of the ion beam, meeting the stringent requirements of medical treatments. Therefore, designing a high-performance compact ECR ion source is crucial for improving the performance and efficiency of medical cyclotrons. In this study, we designed an ECR ion source with a discharge chamber radius of only 25 mm and investigated its plasma formation using a three-dimensional model. We explored the effects of different microwave window positions on the extracted beam current, calculated, and determined the optimal position. Additionally, we studied the variations in the fractions of H⁺, H₂⁺, and H₃⁺ ions in the chamber with respect to pressure and microwave power, and discussed the plasma processes within the ECR ion source chamber based on these findings.