Author: Sheehy, S.L.
Paper Title Page
MOPPD020 A Model for a High-Power Scaling FFAG Ring 409
  • G.H. Rees, D.J. Kelliher, S. Machida, C.R. Prior, S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  High-power FFAG rings are under study to serve as drivers for neutron spallation, muon production, and accelerator-driven reactor systems. In this paper, which follows on from earlier work*, a 20 - 70 MeV model for a high-power FFAG driver is described. This model would serve as a test bed to study topics such as space charge and injection in such rings. The design incorporates a long straight to facilitate H- charge exchange injection. The dynamic aperture is calculated in order to optimize the working point in tune space. The injection scheme is also described. A separate design for an ISIS injector, featuring a novel modification to the scaling law, was also studied.
*G.H. Rees and D.J. Kelliher, “New, high power, scaling, FFAG driver ring designs” HB2010, Morschach, September 2010, MOPD07, p. 54, http://www.
TUPPD021 Orbit Correction in the EMMA Non-scaling FFAG – Simulation and Experimental Results 1455
  • D.J. Kelliher, S. Machida, S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • J.S. Berg
    BNL, Upton, Long Island, New York, USA
  • J.K. Jones, B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • E. Keil
    Honorary CERN Staff Member, Berlin, Germany
  • I.W. Kirkman
    The University of Liverpool, Liverpool, United Kingdom
  The non-scaling FFAG EMMA (Electron Model for Many Applications) is currently in operation at Daresbury Laboratory, UK. Since the lattice is made up solely of linear elements, the betatron tune varies strongly over the momentum range according to the natural chromaticity. Orbit correction is complicated by the resulting variation in response to corrector magnet settings. We consider a method to optimise correction over a range of fixed momenta and discuss experimental results. Measurements of the closed orbit and response matrix are included.  
THEPPB003 A 1 GeV CW FFAG High Intensity Proton Driver 3234
  • S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • C. Johnstone
    Fermilab, Batavia, USA
  The drive for high beam power, high duty cycle, and reliable beams at reasonable cost has focused world attention on fixed-field accelerators, notably Fixed-Field Alternating Gradient accelerators (FFAGs). High-intensity GeV proton drivers are of particular interest, as these encounter duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotron. Recently, the concept of isochronous orbits has been explored and developed for non-scaling FFAGs using powerful new methodologies in FFAG accelerator design. These new breeds of FFAGs have been identified by international collaborations for serious study thanks to their potential applications including Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste. The extreme reliability requirements for ADS mandate CW operation capability and the FFAG’s strong focusing, particularly in the vertical, will serve to mitigate the effect of space charge (as compared with the weak-focusing cyclotron). This paper reports on these new advances in FFAG accelerator technology and presents a stable, 0.25-1GeV isochronous FFAG for an accelerator driven subcritical reactor.