Status of the RAL Front End Test Stand

Letchford, Alan; Clarke-Gayther, M.A.; Faircloth, D. C.; Lawrie, Scott; Perkins, M. J.; Wise, P.; Kurup, A.; Alsari, S.; Jolly, S.; Lee, D. A.; Savage, P.; Pozimski, J.; Gabor, C.; Plostinar, Ciprian; Back, J. J.; Bermejo, Francisco Javier; Enparantza, Rafael; Ariz, I.; Romano, Paul E; Sedano, A.; Etxebarria, V.; Hassanzadegan, Hooman; Garmendia, N.; Eguiraun, M.

doi:10.18429/jacow-ipac2015-thpf105

Cited by 10 publications

(3 citation statements)

References 16 publications

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“…The ion source described in this work has now been delivered to CERN, where it will undergo further in-situ testing in preparation for its proposed integration onto ALPHA. Two additional PELLIS-type sources have also been fabricated, and will be used for Fixed-Field alternating gradient Accelerator (FFA) [14] prototyping on the STFC ISIS Front End Test Stand (FETS) [15] in future.…”

Section: Outlook and Conclusionmentioning

confidence: 99%

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Johnson,

Bertsche,

Cortázar

et al. 2024

J. Inst.

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The CERN ALPHA experiment makes precision measurements of antihydrogen atoms held in a superconducting magnetic minimum trap. Recent studies of the antihydrogen spectrum have provided unique tests of fundamental physics, and to improve on these studies ALPHA is now proposing upgrades to directly compare hydrogen and antihydrogen within their existing atom trap. One route towards producing cold, neutral hydrogen atoms is the integration of a hydrogen ion source into the experiment. Ideally, this should provide both positive (H+, H2 +, H3 +) and negative (H-) ions to facilitate different schemes for producing and trapping hydrogen atoms. For compatibility with ALPHA's existing beamlines, the source must produce modest (∼ 10 μA) beam currents at very low final energies (<100 eV). PELLIS, previously developed at JYFL, is a filament-driven ion source that generates 5–10 keV H- beams with small emittances and tens of microamps of beam current. Here, we present a modified PELLIS design to provide both positive and negative hydrogen ions for ALPHA. The use of an electromagnet filter field in PELLIS allows for the optimisation of H- volume production, and also tuning of the positive ion species fraction. We present simulations of H- (and similarly H+) transport through the initial extraction optics, which have been configured for a lower beam energy of 5 keV and designed to match a proposed beamline to interface with ALPHA. We present the results of detailed vacuum simulations that were used to guide the optics design, allowing the source (at 10-2 mbar) to interface with a transport beamline ∼ 0.5 m downstream that has strict vacuum requirements of < 10-9 mbar. We present experimental results from commissioning of the source, and show that it broadly performs as designed for both positive and negative hydrogen ions.

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Section: Outlook and Conclusionmentioning

confidence: 99%

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Johnson,

Bertsche,

Cortázar

et al. 2024

J. Inst.

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“…Here we describe further development of the Cs balance model and apply it for long pulse (>1 ms discharge pulse) operation. The motivation is twofold: (i) Meeting the 60 mA, 2 ms, 50 Hz specification of the Front End Test Stand (FETS) [3] at RAL requires extending the ion source discharge pulse length to 2.2 ms, first allowing the discharge breakdown oscillations to subside and then extracting the 2 ms H − beam pulse. (ii) A foreseen neutrino super beam upgrade of the ESS facility (ESS𝜈SB) requires 70 mA, 3 ms H − pulses at 14 Hz [4] for which the ISIS Penning source is a contender.…”

Section: Jinst 18 C05023mentioning

confidence: 99%

“…(2.1). The modified Cs balance model was then used to predict the monolayer coverage of the ISIS Penning ion source cathode in two cases: (i) the Front End Test Stand at RAL (FETS) specified to make 60 mA, 2 ms H − beam pulses at 50 Hz repetition rate [3], and (ii) EES𝜈SB requiring 70 mA, 3 ms H − beam pulses at 14 Hz repetition rate [4].…”

Section: Jinst 18 C05023mentioning

confidence: 99%

Caesium balance of the ISIS H^- Penning ion source in long pulse operation

2023

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We have developed a semi-empirical model predicting the equilibrium caesium coverage (in monolayers) and the resulting work function of the ISIS Penning ion source cathode (in eV) in long pulse operation. We use the caesium balance model to predict the temporal structure of the extracted H- beam current pulses and compare the model predictions to experimental data with 60 mA, 2 ms beam pulses at 50 Hz. The experimentally observed droop of the beam current is reproduced by the model. The results imply that extracting square beam pulses in the long pulse operation mode requires more efficient cathode cooling. We apply the model for 70 mA, 3 ms beam pulses at 14 Hz, relevant for ESSνSB project. We conclude that achieving these parameters requires reducing the cathode temperature by 200 °C, and ramping the discharge current to cancel the discharge voltage droop.

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Latest Results from the Front End Test Stand High Performance H[sup −] Ion Source at RAL

Faircloth¹,

Lawrie²,

Letchford³

et al. 2011

AIP Conference Proceedings

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The aim of the Front End Test Stand (FETS) project is to demonstrate that chopped low energy beams of high quality can be produced. FETS consists of a high power Penning Surface Plasma Ion Source, a 3 solenoid LEBT, a 3 MeV RFQ, a chopper and a comprehensive suite of diagnostics. This paper briefly outlines the status of the project, hardware installation and modifications. Results from experiments running the Hion source at 2 ms pulse length are detailed: the discharge current is varied between 20 A and 50 A. The discharge repetition rate is varied between 12.5 and 50 Hz. Hydrogen and Caesium vapour flow rates are varied. The effect of electrode surface temperature and beam current droop are discussed. Peak beam currents of over 60 mA for 2 ms pulse length can be achieved. Normalised r.m.s emittances of 0.3 πmm.mrads at the exit of the LEBT are presented for different source conditions.

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Status of the RAL Front End Test Stand

Cited by 10 publications

References 16 publications

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Caesium balance of the ISIS H^- Penning ion source in long pulse operation

Latest Results from the Front End Test Stand High Performance H[sup −] Ion Source at RAL

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Status of the RAL Front End Test Stand

Cited by 10 publications

References 16 publications

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

Caesium balance of the ISIS H- Penning ion source in long pulse operation

Latest Results from the Front End Test Stand High Performance H[sup −] Ion Source at RAL

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Product

Resources

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Caesium balance of the ISIS H^- Penning ion source in long pulse operation