The role of equilibrium flows in temperature-gradient-driven modes in hot tokamaks

In many major Tokamaks around the world, low frequency micro-instabilities and the ensuing transport are routinely suppressed by a poloidal flow. This poloidal flow could be induced from "outside/externally" or could be self-consistently generated by the plasma processes themselves, for example, shearing fields such as zonal flows. The shear of the poloidal flow thus generated and produces a decorrelation of the mode structure, thus leading to stabilization. They are also believed to play role in L-H transition, which is a phase transition like phenomena from low (L) confinement mode to high (H) confinement mode. In the first part of the work, we present linear global gyro-kinetic formulation to incorporate equilibrium flows in the poloidal and toroidal direction which includes key physics elements such as Landau damping, passing and trapped particle physics, radial and poloidal coupling due to magnetic drifts, FLR effects to all orders and is fully electromagnetic in nature. In the second part we, study the effect of the equilibrium flow on the stability in hot Tokamaks and present some preliminary results. (author)