Resonant magnetic perturbation experiments on MAST using external and internal coils for ELM control

Abstract

Experiments have been performed on MAST using both external ( n = 1, 2) and internal ( n = 3) resonant magnetic perturbation (RMP) coils. ELM suppression has not been achieved even though vacuum modelling shows that either set of coils can produce a region (ΔΨ pol > 0.17), for which the Chirikov parameter is greater than 1, wider than that correlated with ELM suppression in DIII-D. Although complete ELM suppression has not been achieved, application of RMPs has triggered ELMs in ELM free H-mode periods ( n = 3) and increased the ELM frequency in regularly ELM-ing discharges ( n = 2, 3). In addition, the application of RMPs in an n = 3 configuration has produced large changes to the edge turbulence in L-mode discharges.