High-heat flux tests of graphite in-vessel components of T-15MD tokamak with plasma and e-beam load

Abstract

Investigations of samples made of a graphite tile of the lining of the chamber of the T-15MD tokamak with plasma loads simulating the conditions in the peripheral and divertor plasma of a large T-15MD tokamak. When testing samples in a plasma installation PLM with plasma loads of 2 MW/m2 for more than 200 minutes, the surface temperature of the samples reached 1288 ° C. Plasma loading and heating of the surface within the specified limits does not lead to cracking change in the relief and graphite sputtering. The analysis of the morphology and structure of the surface was carried out using the methods of scanning electron microscopy of samples after thermal loads. Surface erosion is insignificant. Long-term plasma loads lead to the growth of a layer of porous carbon structures. The growth rate of structures does not exceed 1–2 μm/h at the maximum heating temperature of the samples and decreases 10 times at 800 ° C. Investigations of graphite samples in an electron-beam setup were carried out with a beam of accelerated 60 keV electrons, which simulates the effect on the graphite lining of the chamber of transient processes expected in the T-15MD tokamak, including ELMs. It is shown that the energy flux of 24 MW/m2 for electron irradiation should be recognized as a threshold for the destruction of the surface of graphite tiles.