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(EX/P3-06) Acceptable ELM Regimes for Burning Plasmas

A. W. Leonard1), T.H. Osborne1), M.E. Fenstermacher2), R.J. Groebner1), M. Groth2), C.J. Lasnier2), M.A. Mahdavi1), T.W. Petrie1), P.B. Snyder1), J.G. Watkins3), L. Zeng4)
1) General Atomics, San Diego, USA
2) Lawrence Livermore National Laboratory, Livermore, California, USA
3) Sandia National Laboratories, Albuquerque, New Mexico
4) University of California, Los Angeles, Los Angeles, California, USA

Abstract.  Small edge-localized-modes (ELMs) are found in the H-mode plasmas of DIII-D for high density and/or high collisionality conditions in the edge pedestal. This is an attractive regime for future burning tokamak plasmas where ELM size must be maintained below a critical threshold in order to avoid ablation of the divertor target. In addition, this small ELM regime maintains a robust edge pedestal pressure that will also be required for achieving adequate central energy confinement in future burning plasmas. This paper reports on the scaling of reduced ELM energy with increasing pedestal density, and/or collisionality, with variations in safety factor q and plasma triangularity. The ELM energy is examined in terms of convected energy, as indicated by a loss of density from the pedestal, and conducted energy, indicated by lost temperature. *Work supported by U.S. Department of Energy under Contracts DE-AC03-99ER54473, W-7405-ENG-48, DE-AC04-AL85000, and Grant DE-FG03-95ER54294.

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IAEA 2003