(IT/P1-14) ELMs and disruptions in ITER:Expected Energy Fluxes on Plasma-Facing Components from Multi-machine Experimental Extrapolations & Consequences for ITER Operation

A. Loarte1), G. Saibene1), R. Sartori1), D. Campbell1), V. Riccardo2), P. Andrew2), G.F. Matthews2), J. Paley2), W. Fundamenski2), T. Eich3), A. Herrmann3), G. Pautasso3), A. Kirk2), G. Counsell2), G. Federici4), G. Strohmayer4), M. Merola4), K.H. Finken5), J. Linke5), G. Maddaluno6), D. Whyte7)8), A. Leonard8), M. Fenstermacher8), R.A. Pitts9), I. Landman10), B. Bazylev10), S. Pestchanyi10), A. Zhitlukhin11), V. Podkovyrov11), N. Klimov11), V. Safronov11), M. Becoulet12), B. Kuteev13), V. Koidan13), L. Khimchenko13)
1) EFDA Close Support Unit Garching, Boltmannstr.2, D-85748 Garching bei München, Germany
2) Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA, United Kingdom
3) Association Euratom-Max-Planck Institut für Plasmaphysik, Boltmannstr.2, D-85748 Garching bei München, Germany
4) ITER International Team, Garching Working Site, Boltmannstr.2, D-85748 Garching bei München, Germany
5) Association EURATOM - Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
6) Association Euratom-ENEA Frascati, via Enrico Fermi 45, 00044 Frascati, Italy
7) Dept. Engineering Physics, University of Wisconsin-Madison, 1500 Engineering Dr., Madison, WI 53706, USA
8) DIII-D National Fusion Facility, P.O. Box 85608, San Diego, CA 92186, USA
9) Centre de Recherches en Physique des Plasmas (CRPP), École Polytechnique Fédérale de Lausanne, Association EURATOM – Conféderation Suisse, 1015 Lausanne, Switzerland
10) Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe, Germany
11) SRC RF TRINITI, Troitsk, 142190, Moscow Region, Russia
12) Association Euratom-CEA, CEA/DSM/DRFC, CEA Cadarache, F-13108 St. Paul-lez-Durance, France
13) Nuclear Fusion Institute,RRC "Kurchatov Institute", Kurchatov sq. 1, 123182, Moscow, Russia

Abstract.  Operation of ITER in high fusion gain regimes comes associated with plasma conditions in which Plasma Facing Components (PFCs) can be subject to large energy fluxes by ELMs and disruptions. These loads can contribute significantly to the overall erosion rate and lifetime of these components. Significant progress in the characterisation of the ELM and disruption transient loads in divertor tokamak experiments has taken place in the last few years. The measurements obtained have provided a physics-based framework on which the expected transient energy loads on ITER PFCs can be estimated. The expected ELM power fluxes depend on the mechanism dominating the energy loss from the plasma during ELMs: conduction and convection. Convective ELMs are associated with small normalised ELM energy losses, which would be compatible with the required lifetime of the ITER PFCs, but are obtained in conditions which are not compatible (pedestal collisionality or normalised energy confinement) with the ITER reference scenario. Studies of the energy balance and power fluxes during disruptions have shown that the thermal energy of the plasma at the thermal quench is a factor of 2-4 lower than that of the full performance plasma for most plasma conditions. Most of the plasma thermal energy during disruptions is deposited on PFCs by conduction/convection during the thermal quench, onto an area which is a factor of 5-10 larger than for normal plasma operation. On the basis of these results, the expected fluxes on the ITER PFCs during transients are : (1) Divertor target. Type I ELM energy fluxes: 0.5-4 MJ/m2 in timescales of 300-600 microseconds, Thermal quench energy fluxes of 2-13 MJ/m2 in timescales of 1-3 ms. (2) Main wall. Type I ELM energy fluxes: 0.5-2 MJ/m2 in timescales of 300-600 microseconds. Thermal quench energy fluxes of 0.5-5 MJ/m2 in timescales of 1-3 ms. Mitigated disruption radiative loads of 0.1-2 MJ/m2 in timescales of 0.2-1.0 ms. The physics models used to perform the extrapolations from present devices to ITER and the results of the experimental and modelling studies carried out to determine the associated erosion of the divertor and main chamber PFCs in ITER and the implications for the plasma discharge and the operation of the device for transient loads in these ranges will be discussed.

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