Gradient-driven instabilities in 2D models for tokamak edge

Tokamak edge plasmas are frequently modeled employing kinetic or fluid equations that assume axisymmetry, that is, physical quantities depend only on the radial and poloidal coordinates, and are independent of the toroidal angle. In these models, turbulent transport due to non-axisymmetric fluctuations is included through ad-hoc diffusion and pinch coefficients. These 2D edge models have been crucial to interpret experimental results, to explain poloidal asymmetries and to study detachment. It has been observed that the inclusion of the radial and poloidal components of the perpendicular drifts in the equations is necessary to reproduce the experimentally observed poloidal variation of density and temperature. In this poster, we show that the inclusion of these drifts leads to novel branches of the Ion-Temperature-Gradient (ITG) and Parallel Velocity Gradient (PVG) instability. These new branches are driven unstable by the poloidal projection of the temperature and velocity gradients, unlike the usual ITG and PVG instabilities, driven by the radial component of these gradients. We will describe the instability in the fluid and kinetic limits, and we will discuss its relevance for edge cross-field transport.