Periodic non-singular invariant series for periodic perturbations of autonomous one-degree-of-freedom Hamiltonians

For periodic perturbations of autonomous 1D Hamiltonians, to all orders in powers of the perturbation parameter, non-singular invariant series periodic in the independent variable are constructed. In applications to magnetohydrodynamic equilibria, the non-singularity has allowed magnetic island structure to be represented within the framework of a perturbation treatment. (C) 1997 Elsevier Science B.V.