Development of an integrated modeling framework for plasma-material interaction and its application on tungsten erosion and transport from the RF antenna structures in the WEST tokamak *

An integrated modeling framework has been developed to study plasma-material interactions (PMI) at the radio-frequency (RF) antenna structures in various magnetic confinement fusion devices. This  requires the integration of several computational tools at various levels of physics fidelity- (1) SOLEDGE2D/SOLPS-ITER for far-SOL plasma profiles (2) Petra-M/COMSOL for RF rectified voltages at the antenna structures, (3)CAD defeaturing of the geometry, (4)GITR for ion energy angle distributions (IEADs) at the material surface, and (5)F-TRIDYN/RustBCA for material erosion yield and surface interaction physics. A 3D Monte-Carlo, particle tracker code- GITR can then predict amount of sputtering-net erosion and deposition- at the antenna structures. Finally, a synthetic diagnostic using S/XB coefficients from collisional-radiative models is developed to compare simulation data with the spectroscopic measurements from experiments. In present case, this entire workflow is applied to an interpretive modeling of ohmic, lower-hybrid and ion cyclotron (IC) RF heated discharges in the WEST tokamak.  The neutral tungsten (W-I) spectroscopic measurements at the WEST RF antenna are compared with results obtained from the modeling. The amount of W-I erosion estimated from the modeling at the WEST RF antenna limiters increases linearly with increase in the power crossing the separatrix (P_sep). The higher charged states of oxygen- O⁶⁺ and beyond- are found to be the dominant species for W-sputtering at the antenna limiters. The results from this modeling matches reasonably well with spectroscopic measurements at the WEST antenna limiters. Currently this framework is also being applied to understand PMI in various other RF-heated linear and toroidal devices.