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T. N. Carlstrom, K. H. Burrell, R. J. Groebner,
F. L. Hinton, M. A. Mahdavi, G. M. Staebler,
A. W. Leonard, T. H. Osborne, and D. M. Thomas
General Atomics, P.O. Box 85608, San Diego, California 92186-5608,
USA
B. A. Carreras, R. Maingi, P. K. Mioduszewski,
L. W. Owen
Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
University of California, San Diego, California, USA
Lawrence Livermore National Laboratory, Livermore, California, USA
J. G. Watkins
Sandia National Laboratories, Albuquerque, New Mexico, USA
Abstract. Sawteeth and neutrals are found to have a significant influence on
the H-mode power threshold scaling. The ion
B drift direction has
only a small effect on the edge plasma conditions measured near the plasma
midplane but a large effect on the divertor plasma. Since the power threshold
changes dramatically with the direction of the ion
B drift, this
implies that phenomena in the divertor region are critical for the
L-H transition. Local conditions at the plasma edge are consistent with
several
theories of the L-H transition that use edge gradients in their formulation of
a critical threshold parameter. However, scatter in the database is too large
to distinguish between conditions that lead to an L-H transition and those
that remain in L-mode.
IAEA 2001
