H^- ion source operational performance and latest development at the Spallation Neutron Source

Abstract

The U.S. Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is the world’s most powerful accelerator-driven pulsed neutron source. An H- injector feeds the accelerator with high current (>50 mA), time structured (1ms, 60 Hz) H- beam. The injector consists of an RF-driven, Cs-enhanced H- ion source and an electrostatic low energy beam transport section. In the recent three run cycles, an H- ion source operated ∼4 months for each run with excellent availability near 99.9%. The presently ongoing run is also on track to finish another ∼4 months run with similar high availability. Lately, we have tested a solid-state RF system for the ion source to replace the existing vacuum-tube type RF amplifier for the sake of improving the ease of operation and maintenance. Progress has also been made on the continued development of an external antenna RF H- ion source with a focus on improvement to its plasma ignition scheme.

Negative hydrogen ion sources for particle accelerators: Sustainability issues and recent improvements in long-term operations

“…The SNS RF ion source routinely produces ~55 mA Hion pulses, 1 ms in duration with a 60 Hz repetition rate [3]. Over time, this source and the Low Energy Beam Transport (LEBT) coupling it to an RFQ, have been improved to now have a >99.9% availability during a typical 4-month operational period [4]. Fig.…”

“…Development of the external-antenna ion source also continues as a contingency source for the SNS should any issues with the internal antennas reemerge [7]. Development of this source now focuses on standardizing build quality of the source and improving the reliability of plasma ignition [4].…”