Multiple ELMs consequences for CFC and W macrobrush target damage in ITER. Numerical simulations vs. experiments.

B. Bazylev1, G. Janeschitz2, I. Landman1, G. Federici3, A.Loarte4, M. Merola5, N. Klimov6, V. Podkovyrov6, A. Zhitlukhin6, J. Linke7, J. Compan7, T. Hirai7

1Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe, Germany

2Forschungszentrum Karlsruhe, Fusion, P.O. Box 3640, 76021 Karlsruhe, Germany

3ITER JWS Garching Co-center, Boltzmannstr. 2, D-85748 Garching Germany

4EFDA-CSU, Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany

5EFDA-European Fusion Development Agreement, D-85748 Garching, Germany

6SRC RF TRINITI, Troitsk, 142190, Moscow Region, Russia

7Forschungszentrum Jülich GmbH, EUROATOM-Association, D-52425 Jülich, Germany


Operation of ITER at high fusion gain is assumed to be the H-mode. A characteristic feature of this regime is the transient release of energy from the confined plasma onto plasma facing components (PFCs) after multiple ELMs (about 104 ELMs per ITER discharge), which can play a determining role in the erosion rate and lifetime of these components. CFC and tungsten macrobrush armour are foreseen as PFC for ITER divertor. During the intense transient events in ITER the evaporation (CFC, W) and surface melting, melt motion, and melt splashing (W) are seen as the main mechanisms of PFC erosion. Due to rather different heat conductivities of CFC fibers a noticeable erosion of the PAN fibers may occur at a rather small heat loads at which the damage to the tungsten armour is not substantial.

For the CFC and W macrobrush structure, the results of erosion simulations after repetitive heat loads caused by ELMs like heat loads with Q= 0.5-3.0 MJ/m2 and τ= 0.3-0.6 ms are presented and compared with experiments at plasma guns. The target melt motion erosion of the W macrobrush is calculated with the fluid dynamics code MEMOS in the ‘shallow water’ approximation, accounting for the surface tension and viscosity of molten metal which have been extended to 3D geometry. The CFC armour erosion is calculated by the 3-dimensional code PHEMOBRID-3D [1] in which 3D heat conductivity properties of CFC are implemented. The numerical simulations are validated by experiments done at QSPA facility (TRINITI). Erosion of CFC and W macrobrush edges faced to the plasma stream under inclined heat loads is investigated.

[1] B.N. Bazylev et al. Physica Scripta, T111, (2004), 213-217.