Wall stabilization of axisymmetric modes in noncircular tokamak plasmas

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Abstract
The axisymmetric stability of tokamak equilibria with arbitrary cross section is studied numerically using the energy principle. The contribution to δW from the plasma region is minimized analytically with respect to displacements in the toroidal and poloidal directions. the formulation of Lüst and Martensen is used for the vacuum contribution. Bessel–Fourier and other sets of trial functions are then employed to cast the minimization of δW into a matrix eigenvalue problem. A computer code named axisym evaluates these matrix elements and solves for the eigenvalues. The code is fully toroidal and compressible mode trial functions are included. Wall stabilization is studied by placing a conducting wall around the vacuum region.