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To predict the impact of removing exhaust heat from the ITER Tokamak, researchers are calling on the Titan supercomputer at the Oak Ridge Leadership Computing Facility in the US.

Using the 27-petaflop behemoth, researchers based at Princeton Plasma Physics Laboratory (PPPL) are simulating the area where the plasma edge meets the divertor—the material structure engineered to remove exhaust heat from the vacuum vessel. Specifically, the team has evaluated the heat-flux width at the divertor, or the width of the material surface that might sustain the highest heat load.

Because the divertor directly faces the exhaust flow, it is bombarded with hot particles driven by electromagnetic fluctuations. In ITER, in order to withstand the highest surface heat load, the divertor will be made of the toughest element on Earth: tungsten.

"You don't want to start and stop ITER too often to replace this divertor material, so it has to be able to withstand the heat load," team leader C.S. Chang reports. "Ideally, we want the hot exhaust particles to hit the surface in a much wider area so that it's not damaged."

Based on simulations made possible by Titan's supercomputing capacity, Chang's team predicts that in ITER, due to the size of the plasma, edge plasma turbulence may spread heat across a larger area of the divertor surface and significantly increase the heat-flux width relative to current smaller-scale fusion devices.

Read the full report on research results at .