• A.P. Letchford, M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie, M. Perkins, P. Wise
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• S.M.H. Alsari, S. Jolly, D.A. Lee, P. Savage
  Imperial College of Science and Technology, Department of Physics, London
• I. Ariz, R. Enparantza, P. Romano, A. Sedano
  Fundación TEKNIKER, Eibar (Gipuzkoa)
• J.J. Back
  University of Warwick, Coventry
• F.J. Bermejo
  Bilbao, Faculty of Science and Technology, Bilbao
• M. Eguiraun
  ESS-Bilbao, Zamudio
• V. Etxebarria
  University of the Basque Country, Faculty of Science and Technology, Bilbao
• C. Gabor, D.C. Plostinar
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• N. Garmendia, H. Hassanzadegan
  ESS Bilbao, Bilbao
• A. Kurup
  Fermilab, Batavia
• J.K. Pozimski
  STFC/RAL, Chilton, Didcot, Oxon

The Front End Test Stand (FETS) under construction at the Rutherford Appleton Laboratory is the UK's contribution to research into the next generation of High Power Proton Accelerators (HPPAs). HPPAs are an essential part of any future Spallation Neutron Source, Neutrino Factory, Muon Collider, Accelerator Driven Sub-critical System, Waste Transmuter etc. FETS will demonstrate a high quality, high intensity, chopped H-minus beam and is a collaboration between RAL, Imperial College and the Universtity of Warwick in the UK and the Universidad del Pais Vasco in Spain. This paper describes the current status and future plans of FETS.

• M.A. Clarke-Gayther
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

A description is given of the development of slow-wave chopper structures for the 3.0 MeV, 60 mA, H‾ MEBT on the RAL Front-End Test Stand (FETS) [1]. 'Helical' and 'Planar' electrode designs [2] have been developed by simulating their high frequency (HF) electromagnetic properties in a commercial 3D code [3], and the manufacture of prototypes has helped to validate the predictive accuracy of the design code, and the selection of suitable machine-able ceramics and alloys of copper and aluminium. A description is also given of a novel abrasive brushing process that enables fine tuning of stripline characteristic impedance by facilitating control of stripline edge radius. The transmission line properties of the previously described 'Helical' test assembly [4] are compared with those of the recently completed 'Planar' test assembly. Finally, the development status of a related prototype high voltage pulse generator is presented.