Is Carbon a Realistic Choice for ITER's Divertor?
Authors: C.H. Skinner and G. Federici
Date of PPPL Report: May 2005
Presented at: the Workshop for New Directions for Advanced Computer Simulations and Experiments in Fusion-related Plasma-surface Interactions for Fusion (21-23 March 2005, Oak Ridge, TN).
Tritium retention by co-deposition with carbon on the divertor target plate is predicted to limit ITER's DT burning plasma operations (e.g. to about 100 pulses for the worst conditions) before the in-vessel tritium inventory limit, currently set at 350 g, is reached. At this point, ITER will only be able to continue its burning plasma program if technology is available that is capable of rapidly removing large quantities of tritium from the vessel with over 90% efficiency. The removal rate required is four orders of magnitude faster than that demonstrated in current tokamaks. Eighteen years after the observation of co-deposition on JET and TFTR, such technology is nowhere in sight. The inexorable conclusion is that either a major initiative in tritium removal should be funded or that research priorities for ITER should focus on metal alternatives.