Characterisation of local ICRF heat loads on the JET ILW

When using Ion Cyclotron Range of Frequency (ICRF) heating, enhanced heat-fluxes are commonly observed on some plasma facing components close to the antennas. Experiments have recently been carried out on JET with the new ITER-Like-Wall (ILW) to characterize the heat flux to the JET ICRF antennas. Using Infra-Red thermography and thermal models of the tiles, heat-fluxes were evaluated from the surface temperature increase during the RF phase of L-mode plasmas. The maximum observed heat-flux intensity was ~ 4.5 MW/m2 when operating with -{\pi}/2 current drive strap phasing at power level of 2MW per antenna and with a 4 cm distance between the plasma and the outer limiters. Heat-fluxes are reduced when using dipole strap phasing. The fraction of ICRF power deposited on the antenna limiters or septa was in the range 2-10% for dipole phasing and 10-20% with +/-{\pi}/2 phasing.Comment: 22 pages, 6 figure

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