(TH/P1-18) Shear Flow Generation due to Electromagnetic Instabilities

**Abstract.** Saturation mechanism for electromagnetic instabilities such as
resistive drift-Alfvén modes (RDAMs) and resistive wall modes (RWMs) has
been studied by solving nonlinear fluid model equations in cylindrical
plasmas. For suppressing nonlinear growth of these modes poloidal shear
flows are essential. However, the Maxwell stress due to magnetic
fluctuations has a tendency to reduce the generation of poloidal flow and
may change nonlinear behavior of these instabilities expected from linear
properties. For weakly unstable RDAMs a stationary poloidal flow is
achieved, although an oscillatory behavior is obtained for fairly unstable
cases. For RWMs the Maxwell stress becomes dominant and an initial poloidal
flow almost disappears near a rational surface particularly when a resistive
wall is close to a main plasma. In case that the resistive wall is not
close, stabilization of RWMs due to a poloidal flow remains.

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*IAEA 2003*