Modelling studies of SOL-divertor plasmas in EAST tokamak with ohmic shots

Modelling studies of SOL-divertor plasmas are carried out using the edge plasma code package B2.5/Eirene-SOLPS5.0. The modelling results are compared with the experimental data of ohmic shots in the EAST tokamak. The profiles of plasma temperature, density, ion flux at the divertor target plates from the modelling are compared with the Langmuir probe profiles. Dα and CIII emissivities from the modelling are also matched to the experimental measurement. The model treats plasma species of deuterium (D) and carbon (C) impurities in a real divertor geometry and an magnetohydrodynamic equilibrium from an experimental shot. Neutral particles of D0 and C0 are traced with Eirene. Properties of low recycling, high recycling and detachment in the divertor plasmas during the density ramp-up are studied at first for an ohmic shot in a discontacted double null configuration. For two ohmic shots with a single null configuration, modelling results of profiles of electron density ne, electron temperature Te, total heat flux Qt and ion saturation flux Γsat are similar to the experimental measurement. The calculated profiles at some positions on the target plates, however, differ from the measured profiles; the calculated ne and Te are one–two times lower than the measured ne and Te, and the calculated Γsat is three–four times lower than the measured Γsat. The calculated Qt profiles along the outer target plate are in better agreement with the measured profiles of Qt, but the peak values of the Qt profiles from the modelling differ from the experimental measurement, which may result from the low spatial resolution of the experimental measurement and the difficulties of measuring peak values with narrow widths.