Realization of high heat flux tungsten monoblock type target with graded interlayer for application to DEMO divertor

Abstract

The divertor is the key in-vessel plasma-facing component being in charge of power exhaust and removal of impurity particles. In DEMO, divertor targets must survive an environment of high heat fluxes (∼up to 20 MW m−2 during slow transients) and neutron irradiation. One advanced concept for components in monoblock configuration concerns the insertion of a compositionally graded layer between tungsten and CuCrZr instead of the soft copper interlayer. As a first step, a thin graded layer (∼25 μm) was developed. As a second step, a thicker graded layer (∼500 μm), which is actually being developed, will also be inserted to study the compliant role of a macroscopic graded layer. This paper reports the results of cyclic high heat flux loading tests up to 20 MW m−2 and to heat flux higher than 25 MW m−2 that mock-ups equipped with thin graded layer survived without visible damage. First feedback on manufacturing steps is also presented. Moreover, the first results obtained on the development of the thick graded layer and its integration in a monoblock configuration are shown.