(EXP3/06) Dependence of Edge Stability on Plasma Shape and Local Pressure
Gradients in the DIII-D and JT-60U Tokamaks
L. L. Lao1), Y. Kamada2),
T. Oikawa2), L. R. Baylor3),
K. H. Burrell1), V. S. Chan1),
M. S. Chance4), M. S. Chu1),
J. R. Ferron1), T. Fukuda2), T. Hatae2),
A. Isayama2), G. L. Jackson1),
A. W. Leonard1), M. A. Makowski5),
J. Manickam4), M. Murakami3),
M. Okabayashi4), T. H. Osborne1),
P. B. Snyder1), E. J. Strait1),
S. Takeji2), T. Takizuka2),
T. S. Taylor1), A. D. Turnbull1),
K. Tsuchiya2), and M. R. Wade3)
1) General Atomics, San Diego, California USA
2) Japan Atomic Energy Research Institute, Naka-machi, Naka-gun,
Ibaraki-ken, Japan
3) Oak Ridge National Laboratory, Oak Ridge, Tennessee USA
4) Princeton Plasma Physics Laboratory, Princeton, New Jersey USA
5) Lawrence Livermore National Laboratory, Livermore, California USA
Abstract. The dependence of edge stability on plasma shape and local
pressure gradients, P', in the DIII-D and JT-60U tokamaks is studied. The
stronger plasma shaping in DIII-D allows the edge region of DIII-D
discharges with Type I (``giant'') ELMs to have access to the second region
of stability for ideal ballooning modes and larger edge P' than JT-60U Type
I ELM discharges. These JT-60U discharges are near the ballooning mode first
regime stability limit. DIII-D results support an ideal stability based
working model of Type I ELMs as low to intermediate toroidal mode number,
n, MHD modes. Results from stability analysis of JT-60U Type I ELM
discharges indicate that predictions from this model are also consistent
with JT-60U edge stability observations.
IAEA 2001
