Implementation and first application of EMC3-EIRENE to EAST double-null divertor

The 3D edge Monte Carlo code coupled with EIRENE (EMC3-EIRENE) has been implemented on the Experimental Advanced Superconducting Tokamak (EAST) and, for the first time, applied to an axisymmetric double null divertor plasma. The code results are compared with Langmuir probe measurements. The cross-field transport coefficients for particle and energy, D⊥ and χ⊥, are determined by fitting the electron density and temperature profiles measured by a reciprocating probe on the outboard midplane. Good agreement between the simulation and probe profiles is obtained when D⊥ and χ⊥ are set to be 0.4 m2 s−1 and 2 m2 s−1, respectively. However, considerable discrepancies in density and temperature profiles are observed downstream. A parameter sensitivity study is carried out to identify the possible causes. Analyzing the numerical results in comparison with the measurements leads to the conclusion that the real separatrix at the outer midplane tends to be located ∼7 mm inward with respect to the last closed flux surface obtained from the equilibrium fitting code.