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Brooks S.J.,RAL
IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference

Magnets with many independently-powered coils can provide nearly arbitrary combinations of multipoles up to a certain order. This paper gives examples of field quality in such an "omni-magnet", which is normal-conducting and simulated with Poisson. Since the magnets also have quite large apertures they may be used to make a general-purpose FFAG and synchrotron test ring for beam dynamics studies. This could use the 3MeV H- beam from the RAL proton Front End Test Stand (FETS) and outline ring parameters are given for that situation. Source

Mouille T.,RAL
IPAC 2014: Proceedings of the 5th International Particle Accelerator Conference

In 2007 a second target station (TS2) was added to the ISIS pulsed neutron source at RAL. Two slow kicker magnets are operated in order to direct a 10 Hz proton beam towards TS2 through the TS2 Extract Proton Beam line (EPB2). When first manufactured and tested, the M25/2 exhibited unforeseen magnetic and thermal behaviour. It was quickly identified that this was caused by the eddy currents induced in the laminated core and the mechanical structure of the magnet. Corrective actions were taken to counterbalance their effects but no further analysis was performed at the time. Recent developments in hardware and software make this analysis more feasible. In this paper we present the results of the transient magnetodynamic simulation that was set up in order to model these eddy currents and study their impact on the M25/2 field quality. Copyright © 2014 CC-BY-3.0 and by the respective authors. Source

Brooks S.,RAL
Physical Review Special Topics - Accelerators and Beams

Fixed field alternating gradient (FFAG) accelerators with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field superconducting magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focusing structure. Scaling-type VFFAGs are found with fixed tunes and no intrinsic limitation on momentum range. This paper presents the first multiparticle tracking of such machines. Proton driver rings to accelerate the 800 MeV beam from the ISIS synchrotron are presented, in terms of both magnet field geometry and longitudinal behavior during acceleration with space charge. The 12 GeV ring produces an output power of at least 2.18 MW. Possible applications of VFFAGs to waste transmutation, hadron therapy, and energy-recovery electron accelerators are also discussed. Source

Brooks S.J.,RAL
IPAC 2011 - 2nd International Particle Accelerator Conference

In this paper it is found that a three-quadrupole focussing system can be morphed continuously through FFD, FDF and DFF variants and back again while maintaining stable optics and even keeping the two transverse tunes constant. This relates to non-scaling FFAGs, where the magnet gradients define both the focussing and the field variation as the closed orbit position changes with momentum. A two-lens focussing system cannot change the sign of either gradient without becoming unstable, meaning non-scaling FFAGs built with such a lattice eventually encounter too large a magnetic field at low energies. However, a theoretical system of magnet field variations using three lenses, with a potentially unlimited energy range and fixed tunes is presented here. Copyright © 2011 by IPAC'11/EPS-AG. Source

Brooks S.J.,RAL
IPAC 2010 - 1st International Particle Accelerator Conference

The neutrino factory requires a source of pions within a momentum window determined by the 'muon front end' accelerator structure downstream [1]. The technique of finding which parts of a large target block are net absorbers or emitters of particles may be adapted with this momentum window in mind. Therefore, analysis of a hadronic production simulation run using MARS15 [2] can provide a candidate target shape in a single pass. However, changing the shape of the material also affects the absorption/emission balance, so this paper investigates iterative schemes to find a self-consistent optimal, or near-optimal, target geometry. Source

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