 |
 |
 |
S. V. Shchepetov, D. K. Akulina, G. M. Batanov,
M. S. Berezhetskii, O. I. Fedyanin, G. A. Gladkov,
S. Grebenshchikov, N. Kharchev, Yu. V. Kholnov,
L. V. Kolik, L. M. Kovrizhnykh, A. B. Kuznetsov,
N. F. Larionova, K. Likin, A. Meshcheryakov,
A. E. Petrov, K. A. Sarksian, I. S. Sbitnikova,
N. N. Skvortsova
Institute of General Physics, Russian Academy of Sciences, Moscow,
Russia
C. Hidalgo, B. van Milligen
EURATOM-CIEMAT, Madrid, Spain
Abstract. Results are reported from experimental study of ECH heated plasma in
the L-2M stellarator with special emphasis on studying the turbulent
processes. It is shown that the total plasma energy at fixed total heating
power is strongly dependent on the plasma position. Visible degradation of
plasma confinement is observed for the inward shifted magnetic configurations
where the stability conditions of ideal interchange MHD modes are violated.
However, even in this case the situation can be improved by decreasing the
average radius of the plasma boundary with the help of graphite limiter
resulting in the increase of the Shafranov shift of magnetic surfaces and
deepening of the magnetic well due to the effect of self-stabilization. This
in turn causes stabilization of ideal MHD interchange modes and visible
increase in plasma energy and volume average value of beta. Statistical
properties of turbulence was studied both for the central part of the plasma
column and for the plasma edge. It is shown that one of the critical factors
determining the coherent structures and turbulent fluxes in the edge plasma is
the radial electric field.
IAEA 2001
