Simulation study on influence of chemically eroded higher hydrocarbons on SOL impurity transport and effect of dynamical material mixing on erosion/deposition of tungsten surfaces exposed to boundary plasmas

Local transport of CD and C+ generated through the reaction chains of CD4, C2D4 and C3D6 chemically eroded from C targets exposed to the boundary plasmas and generated through C0 emitted from the C targets is simulated. The simulation reproduces the CD and CII emission distributions measured in TEXTOR-94. For CD, there are a strong contribution of C2D4 and a weak contribution of C3D6 near the target. For CII, contributions of C2D4 and C3D6 are weak. By changing the C impurity concentration and target temperature, erosion/deposition of W targets exposed near and far from the last close flux surface is also simulated. The near–far asymmetry observed in TEXOR-94, which means erosion of the near target and deposition on the far target, is qualitatively reproduced depending on the plasma parameters, the C impurity concentration and the target temperature.