Driver beam-led EURISOL target design constraints

The EURISOL (European Isotope Separation Online) Design Study is addressing new high power target design challenges. A three-step method [1] was proposed to split the high power linac proton driver beam into one $H^{-}$ branch for the 4 $MW_{b}$ [2] mercury target that produces radioactive ion beams (RIB) via spallation neutroninduced fission in a secondary actinide target and three 100 $kW_{b}$ $H^{+}$ branches for the direct targets producing RIBs via fragmentation and spallation reactions. This scheme minimises transient thermo-mechanical stresses on targets and preserves the cw nature of the driver beam in the four branches. The heat load for oxides, carbides, refractory metal foils and liquid metals is driven by the incident proton driver beam while for actinides, exothermic fission reactions are an additional contribution. This paper discusses the constraints that are specific to each class of material and the target design strategies.