Upgrading the LANSCE accelerator with a SNS RF-driven H- ion source

Martin P Stockli; Baoxi Han; Mike Clemmer; Sarah M Cousineau; Alan Justice; Yoon W Kang; Syd N Murray Jr; Terry R Pennisi; Chip Piller; Chris M Stinson; Robert F Welton; Ilija N Draganic; Yuri K Batygin; Robert W Garnett; David Kleinjan; Jacob L Medina; Joel P Montross; Gary Rouleau; Vadim Dudnikov

doi:10.1063/1.5129673

Upgrading the LANSCE accelerator with a SNS RF-driven H^- ion source

Rev Sci Instrum. 2020 Jan 1;91(1):013321. doi: 10.1063/1.5129673.

Authors

Martin P Stockli¹, Baoxi Han¹, Mike Clemmer¹, Sarah M Cousineau¹, Alan Justice¹, Yoon W Kang¹, Syd N Murray Jr¹, Terry R Pennisi¹, Chip Piller¹, Chris M Stinson¹, Robert F Welton¹, Ilija N Draganic², Yuri K Batygin², Robert W Garnett², David Kleinjan², Jacob L Medina², Joel P Montross², Gary Rouleau², Vadim Dudnikov³

Affiliations

¹ Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
² Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
³ Muons, Inc., Batavia, Illinois 60510, USA.

PMID: 32012569
DOI: 10.1063/1.5129673

Abstract

The LANSCE accelerator is currently powered by a filament-driven, biased converter-type H^- ion source that operates at 10%, the highest plasma duty factor for this type of source, using only ∼2.2 SCCM of H₂. The ion source needs to be replaced every 4 weeks, which takes up to 4 days. The measured negative beam current of 12-16 mA falls below the desired 24 mA acceptance of the LANCSE accelerator. The SNS (Spallation Neutron Source) RF-driven, H^- ion source injects ∼50 mA of H^- beam into the SNS accelerator at 60 Hz with a 6% duty factor and an availability of >99.5% but requires ∼30 SCCM of H₂. Up to 7 A h of H^- have been produced during the 14-weeks-long source service cycles, which is unprecedented for small emittance, high-current, pulsed H^- ion sources. The emittance of the SNS source is slightly smaller than the emittance of the LANSCE source. The SNS source also features unrivaled low Cs consumption and can be installed and started up in <12 h. LANSCE and SNS are working toward the use of SNS H^- ion sources on the LANSCE accelerator because they could (a) fill the LANSCE accelerator to its capacity, (b) decrease the source replacement time by a factor of up to 7, and (c) increase source lifetime by a factor of about 4. This paper discusses some of the challenges that emerge when trying to match a different H^- source into an existing injector with significantly different characteristics and operating regimes.