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  • Time-dependent kinetic factors in ITER scrape-off-layer [Elektronski vir]
    Vasileska, Ivona ; Tskhakaya, David ; Kos, Leon, 1966-
    The divertor targets in tokamaks are constantly bombarded with high-energy neutral and charged particles and such violent events can pose a serious threat to the long-time resistance of the divertor ... materials. The wall erosion, caused by the bombardment, releases impurities, that migrate towards the bulk plasma and due to the effects, the plasma state is deteriorated. In order to limit wall erosion, it is important to estimate the plasma characteristics in the Scrapeoff Layer (SOL) i.e the region outside the last closed magnetic surface (separatrix). However, the transient heat loads such as ELMs (Edge-Localized modes) occur in tokamak edge during H-mode confinement lead to a significant loss of stored plasma energy. Once the ELM-driven plasma pulse has crossed the magnetic separatrix, it travels mainly parallel to the magnetic field lines and ends up hitting the divertor plate. The effects caused by the wall erosion represent the boundary conditions in regions of plasma-surface interaction and the limiting expressions for the parallel heat flux and viscosity. The formulation of kinetic factors (KF) and their time dependence is an interesting and important task for plasma edge studies. The aim of this work was to derive time-dependent KF at the plasma wall transition (PWT) for ELM-free, Type-I ELM and post-ELM states based on a kinetic test simulation. This contribution describes the first results of attempts to address this issue for ITER simulations under high-performance conditions using the 1D3V electrostatic parallel Particlein- Cell (PIC) code BIT1. The burning plasma conditions correspond to the ITER Q = 10, 15 MA baseline at q95 = 3, for which the poloidal length of the 1D SOL is [approximately equal] 20 m from the inner to the outer target, assuming typical upstream separatrix parameters of ne [approximately equal] 3-5 x 10 19 m-3, Te [approximately equal] 100-150 eV and Ti [approximately equal] 200-300 eV. Inclined magnetic fields at targets of ([approximately equal] 5%) are included, as are the particle collisions, with a total of 3.4 x 10 5 poloidal grid cells, giving shortening factors of 20. At a later stage, these will be used as BCs for the calculations of the ELM target heat loads using the SOLPS-ITER code. A typical simulation requires up to 60 days running massively parallel 1152-2304 cores of the EU Marconi super-computer. The duration of the ELM pulse is taken to be between 100-400 [micro]s.
    Vrsta gradiva - prispevek na konferenci
    Leto - 2020
    Jezik - angleški
    COBISS.SI-ID - 49095171