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abstract: 'The generation of zonal magnetic fields in laboratory fusion plasmas is predicted by theoretical and numerical models and was recently observed experimentally. It is shown that the modification of the current density gradient associated with such corrugations can significantly affect the stability of the tearing mode. A simple scaling law is derived that predicts the impact of small stationary current corrugations on the stability parameter $\Delta''$. The described destabilization mechanism can provide an explanation for the trigger of the Neoclassical Tearing Mode (NTM) in plasmas without significant MHD activity.'
author:
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    F. Militello, M. Romanelli, R.J. Hastie, N.F. Loureiro\
    [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK]{}
title: 'Effect of current corrugations on the stability of the tearing mode.'
---

Introduction
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In nature as well as in experimental devices, plasma turbulence generates coherent structures, which can significantly affect the overall behavior of the system. An example in magnetic fusion plasmas is the occurrence of zonal electric fields or zonal flows (the velocity is generated through $\mathbf{E}\times\mathbf{B}$ drifts). The zonal flows are predicted by electrostatic turbulence theory [@Diamond2005] and are observed as mesoscale oscillations in the velocity field, which fluctuates in the radial direction 