Thermal stress analysis of a 3 MW rotating solid target

The structural feasibility of a rotating solid target for potential use at the SNS second target station was evaluated for a beam power of 3MW. The solid target concept consists of a water cooled, segmented, and cladded tungsten disc contained within a stainless steel shroud rotated to distribute energy deposition from a long pulse proton beam. Finite element analysis (FEA) was used to simulate temperature distributions caused by different beam profiles and cooling configurations, and again to evaluate the stress fields resulting from the combination of thermal expansion and mechanical constraint of the tungsten segments. If the segments are split both angularly and vertically, cooling on the top, bottom, and center surfaces can maintain temperatures below 155°C. This cooling configuration, combined with a system of spacers and springs to avoid over constraint, results in stresses well below allowable. A detailed shroud design, incorporating a concave window in order to minimize material in the beam path, results in acceptable stresses with respect to both thermal and internal pressure loads. Although further hydrodynamic evaluation is required to analyze the coolant flow system in detail, the rotating solid target concept is structurally feasible for a beam power of 3 MW.