1 - Nuclear Sciences and Applications - IAEA

STABILITY OF HIGH BETA DISCHARGES
IN THE DIII-D TOKAMAK*
IAEA-CN-50/A-II-l
E.J. STRAIT, L.L. LAO, T.S. TAYLOR, M.S. CHU, J.K. LEE,
A.D. TURNBULL, S.L. ALLEN 1 , N.H. BROOKS, K.H. BURRELL,
R.W. CALLIS, T.N. CARLSTROM, M.S. CHANCE 2 ,
A.P. COLLERAINE, D. CONTENT 3 , J.C. DeBOO, J. FERRON,
J.M. GREENE, R.J. GROEBNER, W.W. HEIDBRINK 4 , F.J. HELTON,
D.N. HILL 1 , R.-M. HONG, N. HOSOGANE 5 , W. HOWL, C.L. HSIEH,
G.L. JACKSON, G.L. JAHNS, A.G. KELLMAN, J. KIM,
S. KINOSHITA 6 , E.A. LAZARUS 7 , P.J. LOMAS 8 , J.L. LUXON,
M.A. MAHDAVI, Y. NEYATANI 5 , T. OHKAWA, T.H. OSBORNE,
D.O. OVERSKEI, T. OZEKI 5 , M. PERRY 3 , P.I. PETERSEN,
T.W. PETRIE, J.C. PHILLIPS, G.D. PORTER 1 , D.P. SCHISSEL,
J.T. SCOVILLE, R.P. SERAYDARIAN, M. SHIMADA 5 , T.C. SIMONEN,
R.T. SNIDER, R.D. STAMBAUGH, R.D. STAV, H. St. JOHN,
R.E. STOCKDALE, U. STROTH 9 , R. WOOD 1
General Atomics,
San Diego, California,
United States of America
Abstract
STABILITY OF HIGH BETA DISCHARGES IN THE DUI-D TOKAMAK.
An operational beta limit of (3 £ 3.5 I/aB has been encountered in neutral beam heated H-mode
divertor discharges in DIII-D, scaling linearly with I/aB over a factor of 3 in I/aB and beta. Carefully
prepared discharges have run stably very close to this limit, with |8 > 3 I/aB having been sustained for
more than 1 s. The maximum beta in such discharges is limited by hard disruptions which are attributed
to the ideal 2/1 kink mode. Before reaching this limit, most discharges experience a saturation or slow
collapse of beta associated with low-n MHD instabilities which are consistent with stability calculations
for resistive pressure-driven modes. As beta increases, MHD instabilities appear in part or all of a
* This is a report of work sponsored by the US Department of Energy under Contract No.
DE-AC03-84ER51044.
' Permanent address: Lawrence Livermore National Laboratory, Livermore, CA, USA.
2
Permanent address: Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA.
3
Permanent address: Johns Hopkins University, Baltimore, MD, USA.
4
Permanent address: University of California at Irvine, Irvine, CA, USA.
5
Permanent address: Japan Atomic Energy Research Institute, Japan.
6
Present address: Hitachi Ltd, Japan.
7
Permanent address: Oak Ridge National Laboratory, Oak Ridge, TN, USA.
8
Permanent address: JET Joint Undertaking, Abingdon, Oxfordshire, United Kingdom.
9
Permanent address: Max-Planck-Institut fur Plasmaphysik, Garching, Federal Republic of
Germany.
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