Computational study of magnetohydrodynamic equilibria with emphasis on fragility of flux surfaces

NSLAB, a variant of the NSTAB code, is being developed and employed to examine non-symmetric magnetohydrodynamic equilibria in a topological torus. The plasma domain is a cube in three space, with periodicity in the y and z coordinates. The code employs the standard variational equilibrium minimization method to obtain the equilibrium state. Studies of the destruction or preservation of flux surfaces, dependent on the choice of boundary conditions, are undertaken, with results being presented. Comparison of cases with zero shear, low shear, and moderate shear are given.