Self-Organized Criticality and Intermittent Turbulence in an MHD Current Sheet with a Threshold Instability

Abstract

We report numerical evidence of a self-organized criticality (SOC) and intermittent turbulence (IT) symbiosis in a resistive magnetohydrodynamic (MHD) current sheet model that includes a local hysteretic switch to capture plasma physical processes outside of MHD that are described in the model as current-dependent resistivity. Results from numerical simulations show scale-free avalanches of magnetic energy dissipation characteristic of SOC, as well as multi-scaling in the velocity field numerically indistinguishable from certain hierarchical turbulence theories. We suggest that SOC and IT may be complementary descriptions of dynamical states realized by driven current sheets -- which occur ubiquitously in astrophysical and space plasmas.