Simulation of redeposition of carbon/hydrocarbon on a material surface with castellated structures

Castellated armor tiles are anticipated to withstand intense heat fluxes on the plasma-facing divertors and limiters. We performed a simulation of the transport and the redeposition of carbon and hydrocarbons on the castellated structure in order to study the mechanisms of redeposition in the gaps using realistic plasma penetration in the gap and their energy- and species-dependent reflection on the surface. The calculated profile for the chemical sputtering, but not the physical sputtering, reproduces the experimental deposition profile within an ITER-like castellation geometry in TEXTOR. From the simulation, we proposed a new castellation geometry. The optimization of the shape of the castellated unit cell is very likely to work to minimize the redeposition rate in the gaps.