An equilibrium analysis of helically symmetries plasmas using boundary element method

The authors present a computational scheme based on boundary-element methods for analyzing helically symmetric equilibrium configurations which are described by the MHD (magnetohydrodynamic) equilibrium equation. To solve the equation numerically, a boundary integral equation is introduced. The authors describe an effective scheme for calculating the principal solution to the equation which includes an infinite series of slow convergence. The vacuum fields enclosed by a helical perfectly conduction shell are calculated on the basis of this scheme. It is shown that the shifts of magnetic surfaces decrease with the helical pitch or the displacement of the helical shell