Progress in high heat flux testing of European DEMO divertor mock-ups

Abstract In the framework of the DEMO divertor project of EUROfusion an extensive R&D program has been carried out to develop advanced design concepts for hot water cooled divertor targets. These plasma-facing components made of W blocks as plasma facing material and CuCrZr as cooling tubes should allow a reliable DEMO operation for 2 h long pulses and maximum heat fluxes up to 20 MW/m². Compared to ITER, the operation at the higher coolant temperature of 150 °C, the longer required lifetime, and the significantly higher neutron fluence are the design challenges exceeding the current extent of experience. In this study we present high heat flux test results of a total of 34 tested W monoblock mock-ups. 14 of them where tested with 20 MW/m² heat flux at DEMO hot water cooling conditions up to now. All tests were performed in the HHF test facility GLADIS from 2016 to 2018. Furthermore, we discuss results from the post exposure investigation of selected concepts of the first R&D phase.