On the Influence of the SOL Region on Core-Plasma Energy Confinement Time in Simulation of Turbulent Transport Processes in Tokamaks

Abstract

The influence of the scrape-off layer (SOL) on the energy confinement time of the core plasma is analyzed by using computer simulation of the self-consistent evolution of turbulence and anomalous transport. The simulation is performed for the conditions of a series of discharges with auxiliary heating in the T‑10 tokamak. It is demonstrated that the role of the SOL region in core-plasma confinement increases considerably relative to the conventional diffusion model of transport processes in the presence of turbulent convection that maintains self-consistency of pressure profiles in plasma. In this case, the influence of the SOL region on the energy confinement time of the core plasma is modeled by nonlinear boundary conditions of the third type at the boundary between the core plasma and the SOL region in which the heat fluxes at the SOL boundary are expressed in the form of power-law dependences on local values of the electron and ion temperatures. The specific form of this power-law dependence is related to power-law scaling for effective plasma confinement time in the SOL. The results of numerical simulation of turbulent-plasma evolution revealed that such an approach allows to provide self-consistent evolution of the energy confinement time τ_E in transient regimes with auxiliary heating, resulting in τ_E attaining stationary values close to those observed in real experiments.