Recent performance of and plasma outage studies with the SNS H- source

M. P. Stockli, B. Han, S. N. Murray, T. R. Pennisi, C. Piller, M. Santana, R. Welton

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Spallation Neutron Source ramps to higher power levels that can be sustained with high availability. The goal is 1.4 MW despite a compromised radio frequency quadrupole (RFQ), which requires higher radio frequency power than design levels to approach the nominal beam transmission. Unfortunately at higher power the RFQ often loses its thermal stability, a problem apparently enhanced by beam losses and high influxes of hydrogen. Delivering as much H- beam as possible with the least amount of hydrogen led to plasma outages. The root cause is the dense 1-ms long ∼55-kW 2-MHz plasma pulses reflecting ∼90% of the continuous ∼300 W, 13-MHz power, which was mitigated with a 4-ms filter for the reflected power signal and an outage resistant, slightly detuned 13-MHz match. Lowering the H2 gas also increased the H- beam current to ∼55 mA and increased the RFQ transmission by ∼7% (relative).

Original languageEnglish
Article number02B140
JournalReview of Scientific Instruments
Volume87
Issue number2
DOIs
StatePublished - Feb 1 2016
Externally publishedYes

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