The effect of neon seeding on plasma edge transport in EAST

Impurity seeding is crucial for power exhaust in future power plants. In the presented analysis, neon seeding for the EAST tokamak is studied. Experiments from the 2019 campaign are taken as a starting point for SOLPS-ITER simulations. In a next step, these simulations are used to study the effect of neon seeding in EAST. It is shown that drift flows are crucial to predict correctly where the ionization sources are located and determines the stagnation point, both for the main ion species (deuterium) as for the neon impurities. Line radiation of neon is only a major contribution to the radiated power fraction when detachement is achieved. In the other cases neutral radiation, and radiation due to background impurities (in the simulations assumed as a carbon-oxygen mixture) is dominating the radiation. This large neutral radiation indicates the importance of neutral transport. In the simulations elastic collisions, ionizing dissociation and charge exchange are considered. Volumetric recombination does not play an important role, even not in the detached simulation. Comparison with findings on other devices shows that the observed patterns are similar. The transport analysis shows that Ne+ leaks towards the core explaining why it is difficult to perform experiments with only neon as a radiative species for EAST-size devices.