Hysteresis in the gyrofluid resistive drift wave turbulence to zonal flow transition

Abstract

The classical drift-fluid (modified) Hasegawa–Wakatani model for quasi-three-dimensional resistive drift wave turbulence in magnetized plasmas is introduced into a gyrofluid model including consistent finite Larmor radius effects. The transition from a turbulence dominated to a strong zonal flow state through variation of the dissipative coupling strength is re-visited and characterized for warm ions. The resulting zonal flow states show a dependence on initial conditions and intermediate temporary changes of parameters, and feature characteristics of hysteresis, such as longer time scales for the decay of zonal flow states into turbulence than for the formation of flows out of turbulence. Zonal flows in warm ion plasmas are also shown to be able to spontaneously merge into flow states with smaller radial mode number and higher flow energy in simulations with long run times.