Nonlinear theory of the formation of magnetic islands in a transition layer with magnetic shear

The nonlinear dynamics of magnetic islands is analyzed during the onset of the tearing-mode instability in a transition layer (a current layer) with a strong magnetic field along the current direction (a magnetic shear) in the collisionless case. The energy spectra of the particles accelerated near the boundary of the region separating closed and unclosed magnetic surfaces are derived. It is shown that, in contrast with one-dimensional perturbations, two-dimensional perturbations do not stop growing even at an island width w>Δ/sub i/>Δ/sub e/ where Δ/sub j/ is the so-called thickness of the singular region for the particles of species j