Operation of RF-driven negative hydrogen ion source in China Spallation Neutron Source

Area of Science:

• Physics
• Accelerator Technology
• Plasma Physics

Background:

• The China Spallation Neutron Source (CSNS) aims to upgrade its beam power to 500 kW.
• Improving ion source performance is critical for achieving higher beam power.

Purpose of the Study:

• To develop and commission an RF-driven negative hydrogen (H-) ion source for the CSNS upgrade.
• To extract the first negative hydrogen ion beam from the newly developed source.

Main Methods:

• Design and construction of an RF-driven H- ion source with a silicon nitride ceramic plasma chamber and a 4.5-turn antenna.
• Plasma ignition using a pulsed DC spark gap, followed by RF power drive from a 2 MHz solid-state amplifier.
• Commissioning of the ion source starting January 2019.

Main Results:

• The ion source produced approximately 20 mA of H- beam current.
• The beam was extracted at an RF power of 32 kW and a pulse width of 450 μs.
• Successful initial extraction of negative hydrogen ion beam achieved.

Conclusions:

• The developed RF-driven H- ion source shows promising performance for the CSNS upgrade.
• The implemented technologies and initial results support further development towards the 500 kW target.
• This work demonstrates the feasibility of the new ion source design for high-power spallation neutron sources.