Development of a Novel DEMO divertor target: spiral plate module

In DEMO, the divertor must endure steady state loads of 10 MW m −2 and transient thermal cycling up to 20 MW m −2 . A novel divertor target, termed the Spiral Plate Module (SPM) and designed to meet these loads, was initially optimized by a one-dimensional, steady-state model. The best design was a trade-off between the wall overheat ( τ s )—a figure of merit for cooling performanceand the pumping ratio ( η P )—a comparison of the pressure drop and the incident heat flux on a target surface. A three-dimensional, steady-state, conjugate heat transfer study showed significant correlation to the one-dimensional model. Compared to other divertor target concepts, the SPM achieved the lowest wall overheat of any target design. The hydraulic performance was also on par with comparable designs, demonstrating a very low pumping ratio. This novel, modular divertor target could be used in future fusion power plants to effectively cool the plasma facing components with low pressure drop.