Front End Test Stand (FETS) - Continuation

Lead Research Organisation: Imperial College London
Department Name: Physics


High power proton accelerators (HPPAs) are at the heart of many future large scale scientific facilities such as a spallation-neutron source, Neutrino Factory, high energy physics at the energy or intensity frontier, accelerator driven sub-critical systems, and the transmutation of nuclear waste. Controlling beam-loss induced machine activation during injection into a circular accelerator (synchrotron or FFAG) is essential for safe operation of HPPAs and requires the beam in the injector linac to be chopped very precisely at the synchrotron revolution frequency. The Front End Test Stand (FETS) at RAL has as its primary aim to demonstrate perfect chopping of a high quality, high intensity, negative Hydrogen ion beam at an energy of 3 MeV.
Although primarily a hardware construction project, the FETS collaboration has become an efficient mechanism for sharing the wealth of real-world accelerator expertise within ISIS and the ASTeC Intense Beams Group with the wider academic community as well as benefitting from the specialisations and expertise of the university groups. The work already undertaken has contributed to the UK's continuing international reputation as a centre of excellence and has stimulated collaborations with leading international accelerator institutes such as CERN, FNAL, ESS and CNS.
FETS consists of a high-brightness Penning surface plasma negative-hydrogen-ion source, magnetic Low Energy Beam Transport (LEBT) at 65 keV to match the beam into a 3 MeV Radio Frequency Quadrupole (RFQ) operating at 324 MHz which delivers the 60mA beam to the Medium Energy Beam Transport (MEBT) where the chopping systems are situated. Comprehensive, state-of-the-art diagnostics measure the performance of the system and the beam quality. The ion source, LEBT and high power RF systems have been commissioned and the manufacture of the RFQ is underway.
With this proposal we seek the resources to complete the construction of FETS in a timely manner. This will entail:
The installation, testing and commissioning of the RFQ;
Accelerating the desired beam intensity and beam quality through the RFQ;
The completion of the engineering design and the manufacture of the chopper systems;
The installation, testing and commissioning the MEBT and chopper systems;
The transmission of beam through the MEBT and the demonstration of precise and efficient beam chopping; and
Evaluating the performance of the complete test stand.
In addition, we proposed to evaluate the additional benefits that will accrue from exploiting the FETS as a driver for further developments in proton accelerator systems.

Planned Impact

Please see the main text of the proposal in the attached file.


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Alsari S (2015) Use of phase information with a stepper motor to control frequency for tuning system of the Front End Test Stand Radio Frequency Quadrupole at Rutherford Appleton Laboratory in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Bogomilov M (2014) Neutrino factory in Physical Review Special Topics - Accelerators and Beams

Description Once finished FETS will enable to built proton accelerators with significantly increase beam power. This research is of relevance for the high energy physics community, for the production of safe nuclear power and nuclear waste transmutation and for cancer treatment using hadron beams
Exploitation Route Include the techniques developed to improve existing particle accelerators or to built new accelerators.
Sectors Energy,Environment,Healthcare

Description First results have already been used to measure beam emittance at the LINAC4. Upon completion of FETS it is expected that techniques developped for FETS will influence the construction of particle accelerators worldwide.
First Year Of Impact 2014
Sector Education,Energy,Healthcare,Other
Impact Types Economic

Description CERN 
Organisation European Organization for Nuclear Research (CERN)
Country Switzerland 
Sector Academic/University 
PI Contribution Exchange of information including technical drawings on beam transport and diagnostic devices with the Instrumentation and Linac 4 group. Installation of FETS laser system at Linac4, first measurements of H- beam profile and beam emittance in Europe using this novel technique. Measurements at 12 MeV and 50 MeV followed . Measurements campaigns helped to strengthen links to CERN and feeds into built and comission a similar system at FETS with options to be used at ISIS in the future. Following the successful first measurements of the LINAC4 beam emittance at 12 MeV using photodetachment a n extension of the collaboration to include the development of a longitudinal emittance measurement device has been discussed with CERN representatives. Latest extension is on the information exchange on fast chopping structures (since end of 2015). In 2016 the collaboration has been working on the Laser wire setup and the fast chopping device. Laser wire measurements have been performed on Linac 4
Collaborator Contribution Exchange of information including technical drawings on beam transport and diagnostic devices with the Instrumentation and Linac 4 group. CERN did make significant contributions to the design of the FETS chopper device (electromagnetic design and mechanical design) using their expertise in running the LINAC4 chopper device.
Impact BPM design - experimental comparison of stripline and button BPM at FETS.
Start Year 2012
Description ESS Bilbao 
Organisation ESS-Bilbao
Country Spain 
Sector Charity/Non Profit 
PI Contribution Share of Ion source and other technical information about FETS, contribution to commissioning of IS. Design of RFQ. Particle transport & space charge. In 2016 the collaboration was extended to include the LLRF system that was developed in Bilbao (Bilbao University). The LLRF system was upgraded to allow adoption to the FETS frequency of 324 MHz. The system has been tested at the FETS in recent months and a final adoption to the FETS hardware is underway. The system implemented will allow to control the RFQ and the 3 rebunching cavities.
Collaborator Contribution Solenoids, technical drawing for couplers, low level RF system for RFQ and rebunching cavities, circulator. High power RF beam dump for final high power RF circulator test. LLRF system for RFQ and the 3 rebunching cavities.
Impact significant progress on FETS and Bilbao Front end.
Start Year 2008
Description PASI 
Organisation Fermilab - Fermi National Accelerator Laboratory
Country United States 
Sector Public 
PI Contribution Exchange of information and `staff. Measurement on lifeftime of scintillators for intense H- beam. Exchange on performance and lifetime of H- ion sources, low energy space charge compensated transport, RF structures & distribution, beam choppers, Laser diagnostics.
Collaborator Contribution Measurements made at Fermilab on their HINS front end. Information exchange. Exchange on ion source performance and upgrades. Exchange on choppers. Exchange of information concerning the implementation of accelerator devices based on Lasers (Laser notchers, Laser diagnostics)
Impact liftetime of scintillators seems no longer an issue for FETS, contributions to the accelerator upgrade for the DUNE project is under discussion.
Start Year 2012