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Author(s):
G.Y.Yu, M. Okamoto, H. Sanuki and T. Amano
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Title:
Effect of Plasma Inertia on Vertical Displacement Instability in Tokamaks
Date of publication:
Mar. 1996
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Key words:
vertical displacement instability, plasma inertia, nonlinear behavior, tokamak
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Abstract:
The effect of plasma inertia on vertical displacement instability (VDI) is investigated in both linear and nonlinear regimes. In a linear case, the solution of the dispersion shows the existance of a critical elongation for a certain distance of the conducting wall. In the nonlinear case a difference between the cases with and without inclusion of plasma inertia is found. The inclusion of the plasma inertia leads to a "softening" of the critical behavior of the displacement against the distance of the resistive wall. Without inclusion of plasma inertia there exists a critical distance between the wall and the plasma below which VDI can not be stabilized no matter how the parameters in feedback controlling scheme are set. An analysis of the dispersion of linear VDI shows that the plasma inertia plays an important role in the properties of the solutions of dispersion and hence in the behavior of VDI.
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