He-cooled divertor for DEMO: Technological studies and experimental verification of the design

A modular He-cooled divertor concept for DEMO is being investigated at Forschungszentrum Karlsruhe (FZK) within the framework of the EU power plant conceptual study. The design goal is to reach a heat flux of at least 10 MW/m
²
. The reference divertor design is based on the use of a tungsten tile which is brazed to a thimble made of W-1 wt%La
₂
O
₃
cooled by helium impingement jets. The current divertor work programme focuses on manufacture and high-heat-flux tests of prototypical tungsten mock-ups to demonstrate the manufacturability and the performance of the design. Till now three high-heat-flux test series on 1-finger mock-ups were successfully performed in a combined helium loop and TSEFEY facility at Efremov. Technological study on fabrication of a 9-finger module of stain less steel was carried out. First gas flow tests showed uniform mass flow rate distribution which agrees well with calculation results. These initial test results confirm the performance of this concept and serve as a strong basis for further development of the material and concept and more integrated testing.