ITER divertor design

This paper reviews the status of ITER divertor design as described in the Interim Design Report. The ITER divertor must exhaust 300 MW alpha heating power and helium ash. It must also withstand huge loads of electromagnetic force and heat flux associated with disruption. The divertor should also be efficiently replaced with remote maintenance. Recent divertor experiments and modelling suggest that the radiative divertor approach may provide a feasible solution to the power and particle exhaust. Compatibility of radiative divertor with good confinement (H∼2) and high purity (Zeff∼1.5) is yet to be demonstrated, and the physics of high density limit remains to be a challenge. The present divertor design based on a cassette scheme is feasible with remote maintenance. Mechanical loads predicted presently are very demanding, but recent progress in VDE (Vertical Displacement Event) control in JT-60U may bring out drastic reduction of its frequency and consequence. (author)