Journal article

First EMC3-Eirene simulations of the TCV snowflake divertor

One of the approaches to solve the heat load problem in a divertor tokamak is the so called 'snowflake' (SF) configuration, a magnetic equilibrium with two nearby x-points and two additional divertor legs. Here we report on the first EMC3-Eirene simulations of plasma-and neutral particle transport in the scrape-off layer of a series of TCV SF equilibria with different values of sigma, the distance between the x-points normalized to the minor radius of the plasma. The constant cross-field transport coefficients were chosen such that the power-and particle deposition profiles at the primary inner strike point (SP) match the Langmuir probe measurements for the sigma = 0.1 case. At the secondary SP on the floor, however, a significantly larger power flux than that predicted by the simulation was measured by the probes, indicating an enhanced transport across the primary separatrix. As the ideal SF configuration (sigma = 0) is approached, the density as well as the radiation maximum are predicted to move from the target plates upward to the x-point by the simulation.

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