Simulation study of density dynamics effect on the ELM behavior with TOPICS-IB

Density dynamics effect on the edge-localized-mode (ELM) behavior has been studied by using an integrated simulation code TOPICS-IB based on a 1.5 dimensional transport code with a stability code of peeling-ballooning modes and a transport model of scrape-off-layer (SOL) and divertor plasmas. Neutral models of core and SOL-divertor regions have been integrated with the TOPICS-IB. The TOPICS-IB successfully simulates the behavior of the whole plasma with density dynamics. It is confirmed by varying the density and the temperature instead of artificially enhancing the collisionality in the previous study that the experimentally observed collisionality dependence of the ELM energy loss is caused by the bootstrap current and the SOL transport. Additionally, ion convective and charge-exchange losses are found to enhance the collisionality dependence by the equipartition effect. On the other hand, the ELM particle loss is found to be almost independent of the collisionality, as shown in experiments, due to the density profile before the ELM and the increase of the SOL density during the ELM in addition to the bootstrap current effect.