Paper | Title | Page |
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TUPTS009 | Operating the SNS RF H− Ion Source with a 10% Duty Factor | 1951 |
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Funding: This work was performed at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 and at Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the U.S. Department of Energy. The SNS (Spallation Neutron Source) (radio-frequency) RF-driven, H− ion source injects ~50 mA of H− beam into the SNS accelerator at 60 Hz with a 6% duty factor. It injects up to 7 A·hrs of H− ions during its ~14-week service cycles, which is an unprecedented lifetime for small-emittance, high-current pulsed H− ion sources. The SNS source also features unprecedented low cesium consumption and can be installed and started up in <10 h. Presently, the LANSCE (Los Alamos Neutron Science CEnter) accelerator complex in Los Alamos is fed by a filament-driven, biased converter-type H− source that operates with a high plasma duty factor of 10%. It needs to be replaced every 4 weeks with a ~4 day startup phase. The measured negative beam current of 16-18 mA falls below the desired 21 mA acceptance of LANSCE’s accelerator especially since the beam contains several mA of electrons. LANSCE and SNS are exploring the possibility of using the SNS RF H− source at LANSCE to increase the H− beam current and the ion source lifetime while decreasing the startup time. For this purpose, the SNS H− source has been tested at a 10% duty factor by operating it at 120 Hz with 840 µs plasma pulses generated with ~30 kW of 2 MHz RF power, and extracting ~25 mA around-the-clock for 28 days. This, and additional tests and other considerations are discussed in this paper. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS009 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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TUPTS025 | Arc and Convertor Current Transient Studies for Multi-cusp Cesiated Surface Conversion H− Source at Lansce | 1983 |
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The Multi-cusp Cesiated Surface Conversion H− Ion Source at the Los Alamos Neutron Science Center (LANSCE) has provided beam at ~14 mA, 120 Hz, and 10% D.F. for many years of neutron science research. Recently, random high current transients were discovered in the arc current used to ionize hydrogen in the LANSCE H− ion source, and in the convertor current used to convert protons to H− ions. Most have no effect, but more severe transients can cripple beam output. Hypothesized causes are related to cesiation effects, plasma potential changes, tungsten filament vaporation/sputtering, or from the pulsed power system. A dedicated study was recently done on the LANSCE H− Ion source test stand to determine the cause of these transients. Current understanding indicates that the more severe transients come from a combination of cesiation effects and plasma potential changes. The status of these current transient studies on the LANSCE H− ion source will be discussed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS025 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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TUPTS071 | H+ and H− Ion Beam Injectors at LANSCE: Beam Production Status and Planned Injector Upgrades | 2087 |
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The Los Alamos Neutron Science Center operates with two 750 keV Cockcroft-Walton accelerators for simultaneous injection of H+ and H− ion beams into a 800 MeV linear accelerator. The proton ion beam is produced using a duoplasmatron source and the H− ion beam is formed with a cesiated, multi-cusp-field, surface converter ion source. An overview of ion injector status, recent low energy beam transport line optimizations and ion source performance improvements will be presented. To reduce long term operational risks and to improve existing LANSCE beam production for all facility users, new injector upgrades are underway: 1) replacing the H+ CW injector with a Radio-Frequency Quadruple accelerator and 2) increasing H− ion beam brightness and extending source lifetime using the novel SNS RF negative ion source. The status of upgrade projects will be discussed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS071 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |