Model validation of tungsten erosion and redeposition properties using biased tungsten samples on DiMES

An experiment was performed in the DIII-D lower divertor to validate numerical SOL tungsten (W) impurity erosion and redeposition simulations against experimental data. The net and gross erosion of W were calculated as a function of the voltage (or bias) applied to the exposed material. Five samples were inserted into the DIII-D lower divertor using the Divertor Material Evaluation System (DiMES) manipulator and exposed to constant L-mode attached plasma conditions. Each sample was partially coated with W. During plasma shots, samples were biased with respect to the machine vessel ground, ranging from −60 V to 25 V. The ERO2.0 code was used to numerically simulate the experiment aiming to compare the numerical results with experimental measures. A good agreement is found between estimated and measured tungsten erosion at least for negative biases. •The surface electric potential of an exposed material affects its erosion rate.•W targets were inserted in the lower divertor of DIII-D and exposed to plasma.•Net and gross erosion were experimentally measured with RBS and UV spectrometer.•Measurements were compared with numerical results obtained with ERO2.0.