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Letchford, A.P.

Paper Title Page
MOP009 Status of the RAL Front End Test Stand 70
 
  • A.P. Letchford, M.A. Clarke-Gayther, D.J.S. Findlay, S.R. Lawrie, P. Romano, P. Wise
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • S.M.H. Al Sari, S. Jolly, A. Kurup, D.A. Lee, P. Savage
    Imperial College of Science and Technology, Department of Physics, London
  • J. Alonso
    Fundación Tekniker, Elbr (Guipuzkoa)
  • J.J. Back
    University of Warwick, Coventry
  • F.J. Bermejo
    Bilbao, Faculty of Science and Technology, Bilbao
  • R. Enparantza
    Fundación TEKNIKER, Eibar (Gipuzkoa)
  • D.C. Faircloth, J. Pasternak, J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon
  • C. Gabor, D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • J. Lucas
    Elytt Energy, Madrid
 
 

High power proton accelerators (HPPAs) with beam powers in the several megawatt range have many applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London, the University of Warwick and the Universidad del Pais Vasco, Bilbao. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational conditions. This paper describes the current status of the RAL Front End Test Stand.

 

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MOP088 Particle Dynamics Calculations and Emittance Measurements at the FETS 281
 
  • J.K. Pozimski, S. Jolly
    Imperial College of Science and Technology, Department of Physics, London
  • J.J. Back
    University of Warwick, Coventry
  • D.C. Faircloth, A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • C. Gabor, D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
 

In order to contribute to the development of high power proton accelerators in the MW range, to prepare the way for an ISIS upgrade and to contribute to the UK design effort on neutrino factories, a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. The results of numerical simulations of the particle dynamics from the charge separation dipole behind the ion source to the end of the MEBT will be presented. Previous measurements showed that the emittance of the beam delivered by the ion source exceeded our expectations by more than a factor of 3. Since then various changes in the beam extraction/post accelerator region reduced the beam emittance by a factor of 2. Simulations of the particle dynamics in the FETS based on distributions gained from recent measurements of the transversal beam emittance behind the ion source will be presented and the results for different input distributions discussed.

 
TUP084 Emittance Measurement Instrument for a High Brilliance H- Ion Beam 594
 
  • C. Gabor, C.R. Prior
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon
 
 

Funding: Work supported by EU/FP6/CARE (HIPPI) RII3-CT-2003-506395
Among present challenges for beam diagnostics and instrumentation are issues presented by high beam intensity, brightness, resolution and the need to avoid inserting mechanical parts into the beam. This very often means applying non-destructive methods, which avoid interaction between ions and mechanical parts and, furthermore, allow on-line measurements during normal beam operation. The preferred technique for H- beams is the photo-detachment process where (laser) light within the range of 400-1000 nm has a sufficient continuous cross section to neutralize negative ions. The actual diagnostics are then applied to either the neutrals produced or the electrons. The latter are typically used for beam profiles whereas neutrals are more suitable for emittances, and form the subject of the present paper. This provides an overview of the basic features of the diagnostic technique, followed by a more intensive discussion of some experimental and theoretical aspects with emphasis on computing the 4 dimensional emittance using a method called Maximum Entropy (MaxEnt).

 

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Slides

 
THP065 Shunt Impedance Studies in the ISIS Linac 942
 
  • D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
 
 

The ISIS linac consists of four DTL tanks that accelerate a 50 pps, 20 mA H- beam up to 70 MeV before injecting it into an 800 MeV synchrotron. Over the last decades, the linac has proved to be a strong and reliable injector for ISIS, which is a significant achievement considering that two of the tanks are more than 50 years old. At the time the machine was designed, the limited computing power available and the absence of 3D electromagnetic (EM) simulation codes, made the creation of a linac optimized for power efficiency almost impossible, so from this point of view, the ISIS linac is quite simple by today's standards. In this paper, we make a shunt impedance comparison study using the power consumption data collected from ISIS and the results obtained when simulating each of the four DTL tanks with 2D and 3D EM codes. The comparison will allow us to check the accuracy of our simulation codes and models and to assess their relative performance. It is particularly important to benchmark these codes against real data, in preparation for their use in the design of a proposed new linac, which will replace the currently aging ISIS injector.