Zonal Flow Dynamics and Shear Layer Collapse in High-Density regime*

We report on a numerical study of the Hasegawa-Wakatani drift-wave model that we have recently adopted for describing the zonal flow drift wave (ZF-DW) interactions. A quasi-linear derivation of the system is provided in detail elsewhere (R.J. Hajjar et al. Physics of Plasmas 25, 062306 (2018); doi: 10.1063/1.5030345). It consists of the three equations for averaged plasma density, and zonal flow speed, along with the fluctuating fields accounted for by the enstrophy. The latter is introduced as an averaged square of potential vorticity fluctuations, by analogy to the quantity oft-used in the studies of geostrophic flows. We investigate the generation of zonal flow and collapse of an edge shear layer depending on the adiabaticity parameter. Critical issues to be addressed here include the radial scale over which ZFs collapse and depth of penetration of the resulting inward turbulence spreading. The work is ongoing, and we will add a particle source at the edge along with simple treatment of heat transport to investigate the depth of cooling resulting from the ZF collapse.