Numerical investigation of toroidal plasma response for ELM control via magnetic perturbations in the DTT Tokamak

Linear plasma response modeling is exploited in this work to assess the effect of different coil configurations on edge localized mode (ELM) stability in full power operational scenarios for the Divertor Tokamak Test (DTT) facility, presently under construction at the ENEA site of Frascati (Italy). The MARS-F code is used to compute, in toroidal geometry and including flow, the resistive plasma response to different vacuum fields with toroidal mode numbers $n\,=\,1,2,3$. Peeling-like response in particular, correlated with ELM control, is found to be significant for $n\,=\,2,3$ perturbations while $n\,=\,1$ induces a large core response in the investigated scenarios. Two metrics are used to link plasma response to ELM control. Namely the local normal plasma displacement in the x-point region and the Chirikov parameter in PEST-like straight-field-line coordinates. These criteria are used to predict optimal phasing of the active coil arrays and current thresholds based on empirical evidence. Depending on the number of active coils and on the scenario, coil currents between 20 and 40 kAt are predicted to be effective for ELM mitigation in DTT.