Suppression of type-I ELMs using a single toroidal row of magnetic field perturbation coils in DIII-D

In recent DIII-D (J.L. Luxon et al 2003 Nucl. Fusion 43 1813 ) experiments, suppression of type-I edge localized modes (ELMs) was obtained by applying n = 3 resonant magnetic perturbations using a single toroidal row of internal, small aperture coils located either above or below the equatorial plane in plasmas with ITER-like electron pedestal collisionality , flux surface shape and low edge safety factor ( q 95 ≈ 3.6). ELM suppression with a single row of coils was achieved at approximately the same q 95 surface-averaged perturbation field as with two rows of coils, but required higher current per coil. Suppression of type-I ELMs was not obtained with similar n = 3 perturbation strength at the q 95 surface from a single-row of external, large aperture coils on the outer equatorial midplane.