Assessment of the sources of uncertainty for the validation of wall erosion models in the WEST tokamak

Quantifying wall erosion in tokamaks is fundamental for determining the impurity sources leading to plasma contamination and assessing the lifetime of plasma-facing components. In order to validate the modeling results on wall erosion obtained from the PSI-2 suite of codes and facilitate successful use of their predictive capabilities for reactor-relevant conditions, we first need to assess the effect the uncertainties have on the modeling results in existing tokamaks. A coupled hybrid particle-in-cell code, hPIC2, with a binary collision approximation code, RustBCA, is used to determine the wall erosion of select few locations in the WEST tokamak, namely a reciprocating collector probe placed in the SOL, and the surface of the RF limiter in front of the ICRH actuator. We have analyzed the effect of three significant sources of uncertainty on the predicted wall erosion: (1) Actual plasma impurity composition, which includes both intrinsic and extrinsic impurities such as oxygen, carbon, copper, residual gases, etc. 2) Charge state distribution of the impurities, and 3) Inverse Photon Efficiency (S/XB), which is finally used for the conversion of sputtering fluxes into observed spectral radiance.

US DOE NNSA LRGF DE-NA0003960