Characterisation of Local ICRF Heat Loads on the JET ILW
When using ICRF, enhanced heat-fluxes are likely to develop 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 characterise this phenomenon. 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 heatflux intensity was ~4.5MW/m2 when operating with -p/2 current drive strap phasing at power level of 2MW per antenna and with a 4cm distance between the plasma and the outer limiters. Heat-fluxes are reduced when using dipole strap phasing. The fraction of ICRF power directly dissipated on the antenna limiters or septa was in the range 2-10% for dipole phasing and 10-20% with -p/2 phasing.