This talk provides a
brief overview of
tokamak experiments. The tokamak is widely recognized
as the most promising candidate for realizing a nuclear
fusion power plant. However,
there still remain many issues to be resolved in order to harness the fusion energy in a
tokamak. The critical parameters for realizing fusion energy reactor can be found in the
fusion triple product ni Ti tE, which results
from a power balance consideration. Here, ni , Ti and tE are the ion density, the ion temperature,
and plasma energy confinement time, respectively. Thus, the tokamak research has been dominated by the search for improved confinement regime (tE ) with high plasma pressure (ni and Ti ).
In this talk, the history
of research into improved confinement regimes such as H-mode and
ITB discharges are
briefly introduced followed by a short overview of theoretical and numerical
models which have been
suggested to understand the confinement regimes. On the one hand, it has
been observed that improved confinement regimes occasionally accompany
several macroscopic magneto-
hydrodynamics (MHD) modes such as tearing
modes and edge localized modes. To avoid
their harmful effects on the plasma
operation, we have to suppress or mitigate them in a reactor-sized tokamak plasma. Here, the experimental efforts in suppressing these MHD modes are briefly discussed. In a reactor-sized tokamak, the high heat flux from high pressure plasma onto the plasma facing components is
also one of
critical issues. Thus, searching
for the effective power exhausting methods has become one of main research goals in fusion community. Several experimental achievements in
this research field are also included in this talk.
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