Active Control of Type-I Edge Localized Modes with n = 1 Perturbation Fields on JET
Type-I Edge Localized Modes (ELMs) have been mitigated at the JET tokamak using a static external n = 1 perturbation field generated by four Error Field Correction Coils (EFCCs) located far from the plasma. During the application of the n = 1 field the ELM frequency increased by a factor of 4 and the amplitude of the Da signal decreased. The normalised energy loss per ELM W/W dropped to values below 2%. Furthermore, the temperature at the outer limiters was also reduced. Transport analyses shows no or only a moderate (up to 20%) degradation of energy confinement time during the ELM mitigation phase.