Momentum/Energy Transport in Predator-Prey Model Associated with Pressure Bump and Shear Flow Background*

Understanding the physics of microinstability in the L-H transition is crucial for magnetic confinement fusion devices. The formation of transport barriers at the plasma edge during the L-H transition allows the plasma to organize itself into a highly conductive state (H-mode). In this transition, the interaction between poloidal zonal flow (ZF) and drift wave (DW) turbulence plays a key role in momentum/energy transport. Analytical studies have shown that ZF, triggered by the L-H transition, suppresses DW turbulence through a self-regulation mechanism involving a shear-eddy feedback loop.

In this study, we present a self-regulation model for the physics of L-H transitions and investigate a 2D simulation of a pure compressible fluid driven by a pressure bump, which creates an environment similar to that of magnetic confinement fusion. We examine the momentum/energy transport among turbulence intensity, ZF, and free energy evolution in the presence of the pressure bump and shear flow background. Our findings indicate that: (1) the evolution of Rossby waves leads to the generation of ZF; (2) the dynamics between DW and ZF regulate the nonlinear stage; (3) the self-binding mechanism of the pressure bump dominates the oscillation frequency. 

Future studies will focus on exploring the implications of self-regulated mechanism on phase transition and transport barriers, and their effect with B-field.