Does ion tearing exist?

Abstract

In a quasi‐neutral sheet the tearing mode is strongly stabilized by electron compressibility. We demonstrate that previous attempts to remove the compressibility by wave turbulent pitch‐angle scattering or by non‐adiabatic stochastic first invariant diffusion are incorrect since these processes do not change the perturbed number of particles on a flux tube. Only spatial diffusion of electrons across magnetic flux surfaces can remove the stabilizing effect of compressibility; in this case, the electron, but not the ion, tearing mode may exist.