Shear Alfven mode resonances in nonaxisymmetric toroidal low-pressure plasmas. II. Singular modes in the shear Alfven continuum

The spatial dependence of modes in the shear Alfven continuum of nonaxisymm etric toroidal magnetohydrodynamic plasma equilibria of zero pressure is in vestigated theoretically. As in configurations with plane or axial symmetry it is found that these modes may exhibit a singularity extended across who le "singular" magnetic surfaces. However, with nonaxisymmetry in the zero p ressure approximation a logarithmic singularity appears in general rather t han the oscillatory singularity of an axisymmetric plasma. If the nonaxisym metry is too strong, the surface-covering property of the singular modes ma y be lost. (C) 2001 American Institute of Physics.