Fabrication and thermal tests of SS/Cu bimetal plate for the use in the concept of flowing liquid lithium layer in tokamak limiters and divertors

A prospective technology for manufacture of the tokamak divertor target based on the concept of flowing liquid lithium layer is described. A small-size bimetal plate was produced by the hot isostatic pressing diffusion bonding of a thick solid copper base, which serves as a thermal sink, and a thin (0.2 mm) stainless-steel foil, which serves as a corrosion-resistance coating. The mock-up with cooling channels in the copper sink was tested by loading the stainless-steel surface by a high heat flux in two loading modes. First, the absorbed heat flux density was increased step-by step from 0.5 MW/m2 to 11.9 MW/m2. Second, thermocycling (1000 cycles) at an absorbed heat-flux density of about 8 MW/m2 was performed. The mock-up demonstrated acceptable uniformity of the temperature on the surface without spot overheating and good stability in thermal cycling in the range of RT-500 °C. No defects were observed after the tests performed.