First experiments with non-axisymmetric magnetic perturbations, toroidal mode number n = 2, produced by newly installed in-vessel saddle coils in the ASDEX Upgrade tokamak show significant reduction of plasma energy loss and peak divertor power load associated with type-I Edge Localized Modes (ELMs) in high-confinement mode plasmas. ELM mitigation is observed above an edge density threshold and is obtained both with magnetic perturbations that are resonant and not resonant with the edge safety factor profile. Compared with unperturbed type-I ELMy reference plasmas, plasmas with mitigated ELMs show similar confinement, similar plasma density and lower tungsten impurity concentration.

Noninductive current drive has been performed in the tokamak ASDEX upgrade by injection of radiofrequency waves at the second harmonic of the electron-cyclotron frequency in order to suppress unwanted disturbances of the magnetic-field configuration. The current has been driven parallel [co-electron cyclotron current drive (ECCD)] and antiparallel (counter-ECCD) to the plasma current to compare the effect of heating with direct current drive in the magnetic island. For the first time it has been shown experimentally that total stabilization of neoclassical tearing modes is possible with co-ECCD. The experiments verify the role of direct current drive as opposed to local heating.

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