Effect of external perturbation fields on divertor particle and heat loads during ELMs at JET

Peak heat fluxes arriving at the JET-divertor during Type-I ELMs have been successfully reduced by applying externally magnetic perturbation fields. The ELM-frequency in these plasmas strongly increases, leading to smaller ELM-size. The concomitant density losses, known as pump-out effect, have been recovered using inboard divertor gas fuelling, albeit with a degradation of the energy confinement. Langmuir probe analysis has shown that the magnetic perturbation drastically reduces the ELM-peak heat flux mostly via a reduction in particle flux, but at the price of higher inter-ELM fluxes. (C) 2009 Elsevier B.V. All rights reserved.