Megawatt upgrades for the isis facility
Thomason JWG., Adams DJ., Findlay DJS., Gardner ISK., Jones B., Letchford AP., Payne SJ., Pine BG., Seville A., Warsop CM., Williamson RE., Plostinar DC., Prior CR., Rees GH.
ISIS is the world's most productive spallation neutron source, at the Rutherford Appleton Laboratory in the UK. Presently, it runs at beam powers of 0.2 MW, with upgrades in place to supply increased powers for the new Second Target Station due to start operation in 2008. This paper outlines favoured schemes for major upgrades to the facility in the megawatt regime, with options for 1, 2 and 5 MW. The ideas centre around new 3.2 GeV Rapid Cycling Synchrotron (RCS) designs that can be employed to increase the energy of the existing ISIS beam to provide powers of ∼1 MW or, possibly as a second upgrade stage, accumulate and accelerate beam from a new 800 MeV linac for 2-5 MW beams. Summaries of ring designs are presented, along with studies and simulations to assess the key loss mechanisms that will impose intensity limitations. Important factors include injection, RF systems, instabilities, longitudinal and transverse space charge.