Key technology of extraction power based on CSNS ion source

Background: The performance of the ion source of China Spallation Neutron Source (CSNS) starting point directly determines the success or the failure of the CSNS project, and the extracted power plays a key role in the ion source. Purpose: This study aims to resolve the critical issues including the MOS tube over-voltage, MOS tube protection circuit and the consistency of driving signal in the multiple MOS tubes working in serial structures. Methods: A high voltage modulation circuit schemed by 40 MOSFET power tubes is designed to inter-connect in series to the obtain high-voltage pulse. A high-frequency transformer of 40 secondary groups is applied to solve MOS tube consistency of driving signal issue with the same resistance in MOSFET drain source to protect MOS tube is not damaged. Results: The correctness of a prototype ion-extraction power supply of AC220V input and output average power of 375 W is verified by theoretical analysis. The experimental results show that the power supply outputs peak pulse voltage of 25 kV, with pulse width of 900 μs pulse current of 600 mA, pulse jitter of 15 ns. The repetition rate is 25 Hz, and the pulse rise time is 200 ns. Conclusion: The power supply meets the requirements for ion source extraction of the negative hydrogen and lays the foundation for the stable operation of CSNS ion source for a long time. (authors)