Evans, T. E.Moyer, R. A.Watkins, J. G.Osborne, T. H.Thomas, P. R.Becoulet, M.Boedo, J. A.Doyle, E. J.Fenstermacher, M. E.Finken, K. H.Groebner, R. J.Groth, M.Harris, J. H.Jackson, G. L.La Haye, R. J.Lasnier, C. J.Masuzaki, S.Ohyabu, N.Pretty, D. G.Reimerdes, H.Rhodes, T. L.Rudakov, D. L.Schaffer, M. J.Wade, M. R.Wang, G.West, W. P.Zeng, L.2025-03-302025-03-30researchoutputwizard:MigratedxPub10538Scopus:22644438981WOS:231000300008https://dspace-test.anu.edu.au/handle/1885/733747443Large sub-millisecond heat pulses due to Type-I edge localized modes (ELMs) have been eliminated reproducibly in DIII-D for periods approaching nine energy confinement times (τE) with small dc currents driven in a simple magnetic perturbation coil. The current required to eliminate all but a few isolated Type-I ELM impulses during a coil pulse is less than 0.4% of plasma current. Based on magnetic field line modelling, the perturbation fields resonate with plasma flux surfaces across most of the pedestal region (0.9 ≤ ψN ≤ 1.0) when q95 ≤ 3.7 ± 0.2, creating small remnant magnetic islands surrounded by weakly stochastic field lines. The stored energy, βN, H-mode quality factor and global energy confinement time are unaltered by the magnetic perturbation. Although some isolated ELMs occur during the coil pulse, long periods free of large Type-I ELMs (Δt > 4-6 τE) have been reproduced numerous times, on multiple experimental run days in high and intermediate triangularity plasmas, including cases matching the baseline ITER scenario 2 flux surface shape. In low triangularity, lower single null plasmas, with collisionalities near that expected in ITER, Type-I ELMs are replaced by small amplitude, high frequency Type-II-like ELMs and are often accompanied by one or more ELM-free periods approaching 1-2 τE. Large Type-I ELM impulses represent a severe constraint on the survivability of the divertor target plates in future burning plasma devices. Results presented in this paper demonstrate that non-axisymmetric edge magnetic perturbations provide a very attractive development path for active ELM control in future tokamaks such as ITER.13English2005-07-0110.1088/0029-5515/45/7/007http://www.scopus.com/inward/record.url?scp=22644438981&partnerID=8YFLogxK