Development of a 1.2 MV high voltage DC power supply with SF6 insulation for an electrostatic tandem proton accelerator in accelerator-based boron neutron capture therapy system

This paper presents the development of a 1.2 MV high-voltage direct current (DC) power supply with an SF6 insulation for an electrostatic tandem proton accelerator utilized in an accelerator-based boron neutron capture therapy (BNCT) system. BNCT offers a promising alternative to traditional radiation therapy for the treatment of malignant brain tumors, head and neck cancers, and melanomas. The electrostatic tandem proton accelerator system, designed to produce H- ions and subsequently accelerate them to generate protons, represents a significant advancement in medical technology. Key milestones in the process include generating and maintaining a high-voltage DC power supply of 1.2 MV/45 mA for over 30 min, with rigorously testing conducted up to 750 kV/45 mA in ambient conditions. The system features an upgraded Cockcroft-Walton rectifier stage and incorporates a realistic load resistance, with final testing conducted in a tank filled with SF6 gas. Performance tests conducted in atmospheric and SF6 gas environments demonstrate the stable operation of the power supply up to 1.2 MV/45 mA, despite challenges such as corona discharge and electrical arcing in atmospheric environments. It demonstrates excellent long-term voltage and current stability, proving its suitability for tandem proton accelerators by reliably supplying 54 W of power to the dummy load. The developed system can enhance the effectiveness of BNCT systems by generating high-current proton beams, leading to improved treatment outcomes.