Qualitative effects of resistivity in JET-ILW Europed pedestal predictions

The effect of resistive MHD in the pedestal predictions for JET-ILW has been investigated, using the Europed workflow [S Saarelma et al, Plasma Phys. Control. Fusion 2018] with the resistive MHD stability code CASTOR [W Kerner et al, J. Comput. Phys. 1998]. The inclusion of resistivity in the MHD stability calculations leads to a destabilisation of the peeling-ballooning (PB) modes. Due to the sensitivity of the predictions using resistive MHD to the stability threshold, the work shows that quantitative conclusions are uncertain and only qualitative conclusions are reliable. The effect of resistivity is shown for different plasma conditions with scans of key parameters. The effect of resistivity is largely dependent on the input electron density pedestal profile (via the pedestal top density and the separatrix density), and less dependent on the normalised plasma pressure. Overall, at high temperatures, the predictions performed with ideal and resistive MHD are comparable. At low temperature, resistive effects are not negligible and the resistive MHD predictions produce a pedestal pressure height and gradient lower than ideal MHD predictions. Europed predictions with resistive MHD are also compared to experimental values from power scans and gas scans in JET-ILW. The use of resistive MHD produces a qualitatively better agreement between Europed predictions and experimental values, compared to ideal MHD predictions. The improvement is seen for the pedestal height and partially also for the pedestal gradient, but not for the pedestal width. Despite the results of the work are only qualitative, the workflow can be used to determine if resistive MHD is necessary to obtain reliable pedestal predictions for future devices.