Magnetic Braiding Due to Weak Asymmetry

Magnetic surfaces for a plasma with a helical current perturbation $\ensuremath{\sim}{\ensuremath{\epsilon}}^{2}$ are destroyed by toroidal effects or by a second current perturbation, of incommensurate helicity, and the behavior of magnetic field lines becomes stochastic in layers of relative width ${\ensuremath{\epsilon}}^{\ensuremath{-}l}\ifmmode\times\else\texttimes\fi{}\mathrm{exp}(\ensuremath{-}\frac{\ensuremath{\pi}}{2\ensuremath{\epsilon}})$, where $l\ensuremath{\sim}2|\frac{{m}_{1}}{m}|+1$ with $m$ and ${m}_{1}$ the azimuthal mode numbers of the original helical field and of the perturbation.