Marginal shearing convection and intermittent heat transport in the edge-SOL plasma

Turbulence and transport are an important problem for magnetically confined plasmas. In particular, turbulent transport plays a crucial role in setting the width of the scrape off layer, and thus it is a critical issue to elucidate the basic physics of turbulent transport in the edge-SOL. In this vein, shearing convection has been discussed as a relevant paradigm to understand turbulence and transport feature in these regions, and former studies feature the intermittent character of fluctuation from numerical studies. While these studies provide interesting perspective, additional, further detailed analysis is called for. For example, it is of interest to analyze shearing convection close to the the marginal state, since once triggered, shearing convection drives heat flux and relax the system toward the marginal state. In this work, we present an analysis of a reduced model to describe the nonlinear dynamics of shearing convection close to the threshold for the onset of convection. Our results indicate that intermittent feature persists in the the marginal state. We also identify zonal flows as a key element for intermittent dynamics.