Kinetic-Fluid Coupling Time-Dependent Simulations Of ITER During ELMs

Edge Localized Modes (ELMs)-induced transient heat loads on the divertor targets represent a important threat to target lifetime and can lead to the need to replace them with a frequency that has a major impact in the execution of the ITER Research Plan. Predicting the impact of such large transient heat loads through modelling is especially challenging and is often attempted through the use of fluid plasma boundary modelling codes, such as SOLPSITER, in which the ELM is crudely approximated as a fixed large, but limited in time, increase in anomalous cross-field transport coefficients for particles and heat to mimic a specified total ELM energy loss. However, one problem with this approach is that the boundary conditions at the target sheath interface are expected to vary strongly in time through the ELM transient. The kinetic heat flux limiters are fixed and typically applied in the fluid codes. Coupling kinetic fluid codes has not yet been systematically used for ITER ELMs study. This contribution describes the first results of efforts to address ELMs issues for ITER simulations under high performance conditions using the 1D3V (1D in space and 3D in velocity) electrostatic parallel Particle-in-Cell (PIC) code BIT1 [1], to study the kinetic effects and to provide time dependent kinetic target sheath heat transmission factors (SHTF). In a later stage of the work, these will be used in the formulation of fluid boundary conditions for calculations of ELM target heat loads using the SOLPS-ITER code. The BIT1-SOLPS-ITER coupling allows us to investigate the kinetic effects on the targets, by comparing power and particle fluxes from time-dependent simulations of ITER Type I ELMs.