Bohm-like dependence of transport in scrape-off layer plasmas

Nondiffusive radial transport in scrape-off layer (SoL) is investigated using the two-dimensional SoL interchange turbulence simulation code, which reproduces plasma blobs. From nonlinear simulations, it is found that a mesoscale convective cell emerges from interchange turbulence and propagates in the radial direction. Blob structures are formed autonomously and their ballistic propagation dominates SoL radial transport. A high-density tail in the radial profile is reproduced. This indicates the existence of a 2nd SoL. The effective transport coefficient is analyzed and a Bohm-like dependence is found. It is concluded that the flux-driven turbulence in SoL induces Bohm-like "nondiffusive" transport. The PDF of the turbulence-driven flux is also investigated. It is found that the PDF distribution follows a stretched Gaussian distribution.