INVESTIGATION OF THE CANDIDATE DIVERTOR MATERIALS EROSION AT THE POWERFUL ELECTRON-BEAM

The powerful electron beam is a rather convenient energy source for th e investigation of the material erosion because its parameters at the target can be determined with sufficient accuracy and can be controlle d in a wide range. The electron beam facility ELDIS being used for inv estigation of the candidate divertor materials erosion has the followi ng parameters: electron energy 60-140 keV, pulse duration 10-60 mu s, power density at the target up to 5 MW/cm(2), minimum beam diameter at the target 1.2 cm, magnetic field at the target up to 4 T. The maximu m energy deposition density had approximately the same value for the m aterials investigated (C, Cu, W) equal to 10-12 kJ/g. In the course of experiments the target erosion and target plasma parameters were dete rmined. Shielding effect is negligible and the erosion is mainly deter mined by the energy deposition of the unattenuated electron beam, The erosion of the graphite targets cannot be explained by surface evapora tion or volumetric sublimation. It seems likely that it is connected w ith intensive evaporation inside the pores causing the material destru ction.