T$_{e}$ and n$_{e}$ profile measurements with HRTS during ELM mitigation experiments with external magnetic perturbation fields on JET

In recent experiments on JET, type-I ELMs in H-mode plasmas have been controlled by a set of 4 error field correction coils (EFCC) which externally generate magnetic perturbation field with toroidal mode numbers n=1 or n=2. The effect of this perturbation on T$_{e}$ and n$_{e}$ profiles has been studied with the High Resolution Thomson Scattering (HRTS) which has recently become operative on JET. The EFCCs effect on ELMs has been investigated in various plasma configurations with different directions of the perturbation field and mode numbers. The edge pedestal barrier is modified in different ways, depending on the configuration. In all cases, ELM mitigation correlates with a reduction of the edge pressure gradient due to a reduced height and an increased width of the edge pressure transport barrier.