Ion source antenna development for the Spallation Neutron Source

Welton, R. F.; Stöckli, M. P.; Kang, Y.; Janney, Mark A.; Keller, R.; Thomae, R.; Schenkel, T.; Shukla, S.

doi:10.1063/1.1431416

Cited by 32 publications

(12 citation statements)

References 7 publications

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“…The RF antenna is made from copper tubing that is water cooled and coiled to 2 ½ turns and centered in the plasma chamber. A porcelain enamel layer insulates the plasma from the oscillating antenna potentials 7 . More details of this source design can be found in reference 8.…”

Section: The Multicusp H -Source and Lebtmentioning

confidence: 99%

Recent Advances in the Performance and Understanding of the SNS Ion Source

Welton¹,

Stöckli²,

Murray³

et al. 2005

AIP Conference Proceedings

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Abstract. The ion source developed for the Spallation Neutron Source* (SNS) by Lawrence Berkeley National Laboratory (LBNL), is a radio frequency, multi-cusp source designed to produce ~ 40 mA of H -with a normalized rms emittance of less than 0.2 pi mm mrad. To date, the source has been utilized in the commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of ~30 mA with duty-factors of ~0.1% for operational periods of several weeks. Once the SNS is fully operational in 2008, a beam current duty-factor of 6% (1 ms pulse length, 60 Hz repetition rate) will be required in order to inject the accelerator. To ascertain the capability of the source to deliver beams at this high duty-factor over sustained time periods, several experimental runs have been conducted, each ~1 week in length, in which the ion source was continuously operated on a dedicated test stand. The results of these tests are reported as well as a theory of the Cs release and transport processes which were derived from these data. The theory was then employed to develop a more effective source conditioning procedure as well as an improved Cs collar design. Initial results of tests employing a Cs collar with enhanced surface ionization geometry are also discussed.

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Section: The Multicusp H -Source and Lebtmentioning

confidence: 99%

Recent Advances in the Performance and Understanding of the SNS Ion Source

Welton¹,

Stöckli²,

Murray³

et al. 2005

AIP Conference Proceedings

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“…The antenna consists of a 2-1/2 winding copper coil, covered by a multi-layer porcelain coating. 7 An antenna with 0.25-mm coating underwent an endurance test at full duty factor, and the test was intentionally stopped after 107 hours and after verifying that the ion source delivered 20 mA of beam current at that time. An upgraded antenna with 0.8-mm thick 10-layer coating produces the same plasma density and beam current for a given rf power level as the thin version (about 0.9 mA per kW of power) and is expected to last significantly longer.…”

Section: Plasma Generationmentioning

confidence: 99%

Design, Operational Experiences and Beam Results Obtained with the SNS H− Ion Source and LEBT at Berkeley Lab

Keller¹,

Thomae²,

Stöckli³

et al. 2002

AIP Conference Proceedings

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Abstract:The ion source and Low-Energy Transport (LEBT) system that will provide H -ion beams to the Spallation Neutron Source (SNS)** Front End and the accelerator chain have been developed into a mature unit that fully satisfies the operational requirements through the commissioning and early operating phases of SNS. Compared to the early R&D version, many features of the ion source have been improved, and reliable operation at 6% duty factor has been achieved producing beam currents in the 35-mA range and above. LEBT operation proved that the purely electrostatic focusing principle is well suited to inject the ion beam into the RFQ accelerator, including the steering and pre-chopping functions. This paper will discuss the latest design features of the ion source and LEBT, give performance data for the integrated system, and report on commissioning results obtained with the SNS RFQ and Medium-Energy Beam Transport (MEBT) system. Prospects for further improvements will be outlined in concluding remarks. INTRODUCTIONBerkeley Lab has just completed building the linac injector (Front End, FE) for the Spallation Neutron Source project (SNS), and the commissioning of the entire system is proceeding. The main subsystems are the H -ion-source, the low-energy beam-transport system (LEBT), the 2.5-MeV radio-frequency quadrupole (RFQ) accelerator, and the medium-energy beam-transport system (MEBT). Ion source and LEBT are the subject of this paper; their task is to create a 65-keV, 38-mA ion beam, to match and steer it into the RFQ, and to pre-chop it into mini-pulses of about 600 ns duration. The nominal duty factor is 6%, with 1-ms macro-pulse length and 60-Hz repetition rate.Based upon the main design features of the SSC ion source, 1 an R&D version of the SNS ion source was built first to demonstrate the viability of the chosen approach, utilizing an rf driven discharge inside a multicusp plasma generator with magnetic filter, cesium enhancement, and electron suppression at low energy.2 This source version did not allow implementing cesium enhancement and electron suppression at the same time, but both features were proven to work satisfactorily in separate tests.

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“…This model is implemented in the USim fluid plasma software [4], with the eventual goal of analyzing the potential for antenna failures in the Spallation Neutron Source negative hydrogen ion source. [5,6] …”

Section: Introductionmentioning

confidence: 99%