Investigation of the Protective Plasma-Facing Graphite In-Vessel Components of T-15MD Tokamak by Steady-State Plasma Loads in the PLM Device and by Powerful Electron Beams

Studies of samples of graphite heat-shielding facing of the T-15MD tokamak chamber with stationary plasma loads in the PLM plasma device and high-power electron beams simulating loads during ELMs and transient processes were carried out. When the graphite facing samples were tested with plasma loads up to 2 MW/m 2 , their surface temperature reached more than 1200°C, the surface heating did not lead to cracking, a change in the relief, or significant erosion of the graphite surface. The plasma action led to the growth of a layer of highly porous carbon structures on the surface in the zone of contact with the plasma column. Irradiation of graphite with electron beams with a load of less than 12 MW/m 2 did not lead to changes in the surface structure; at a load exceeding 24 MW/m 2 , the processes of erosion and cracking of the surface along the grain boundaries began. At thermal cyclic loads exceeding 380 MW/m 2 , effects of significant erosion were observed with a rate of material removal from the graphite surface up to 175 μm/s. The conducted experimental studies and tests are considered as the basis for using the investigated type of graphite as the facing of heat-shielding components of the divertor and the first wall for operation in the T-15MD tokamak.