Abstract
To understand the connection between the dynamics of microscopic turbulence and the macroscale power scaling in the L–I–H transition in magnetically confined plasmas, a new time-dependent, one-dimensional (in radius) model has been developed. The model investigates the radial force balance equation at the edge region of the plasma and applies the quenching effect of turbulence via the E × B flow shear rate exceeding the shear suppression threshold. By slightly ramping up the heating power, the spatio-temporal evolution of turbulence intensity, density and pressure profiles, poloidal flow and E × B flow self-consistently displays the L–H transition with an intermediate phase (I-phase) characterized by limit-cycle oscillations. Since the poloidal flow is partially damped to the neoclassical flow in the edge region, the numerical results reveal two different oscillation relationships between the E × B flow and the turbulence intensity depending on which oscillation of the diamagnetic flow or poloidal flow is dominant. Specifically, by including the effects of boundary conditions of density and temperature, the model results in a linear dependence of the H-mode access power on the density and magnetic field. These results imply that the microscopic turbulence dynamics and the macroscale power scaling for the L–H transition are strongly connected.
Highlights
It is well known that turbulent transport on the edge of the plasma column strongly influences the confinement of particles and energy of a fusion device [1, 2]
We have developed a time-dependent one-dimensional dynamical model to describe self-consistently the evolution of the turbulence intensity, density and pressure profiles, poloidal flows and E × B flow in a magnetically confined plasma
The central point of the model is the application of the decorrelation theory of sheared E × B flow for suppressing turbulence transport for investigating the connection between microscopic turbulence dynamics and the macroscale power scaling for the L–I–H transition
Summary
It is well known that turbulent transport on the edge of the plasma column strongly influences the confinement of particles and energy of a fusion device [1, 2]. This power threshold tends to have different behaviour in lower and higher density regions [16], but appears to increase with higher density, magnetic field and the size of the tokamak It is aimed at bridging the gap between microscopic turbulence dynamics physics and the macroscale power scaling in the L–I– H transition in close compliance with these relevant experiment results. In order to understand the connection between microscopic turbulence dynamics physics and the macroscale power scaling in the L–I–H transition, the radial force balance equation is specially investigated to apply the decorrelation theory of E × B flow shear suppressing turbulence transport [21, 22] driven by the pressure gradient.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
