A New Paradigm for Turbulent Transport Across a Steep Gradient in Toroidal Plasmas

Abstract

First principle gyrokinetic simulation of the edge turbulent transport in toroidal plasmas finds a reverse trend in the turbulent transport coefficients under strong gradients. It is found that there exist both linear and nonlinear critical gradients for the nonmonotonicity of transport characteristics. The discontinuity of transport flux slope around the turning gradient shows features of second order phase transition. Under strong gradient the most unstable modes are in non-ground eigenstates with unconventional mode structures, which significantly reduces the effective correlation length and thus reverse the transport trend. Our results suggest a completely new mechanism for the low to high confinement mode transition without invoking shear flow or zonal flow.

arXiv comment5 pages, 7 figures, accepted by Phys. Rev. Lett

References in corpus (1)

• Unconventional Ballooning Structures for Toroidal Drift Waves

Cited by in corpus (8)

• Deep learning based surrogate model for first-principles global simulations of fusion plasmas
• Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes
• Flow Shear Suppression of Pedestal Turbulence--A First Principles Theoretical Framework
• Kinetic Ballooning Mode Under Steep Gradient: High Order Eigenstates and Mode Structure Parity Transition
• Local Gyrokinetic Study of Electrostatic Microinstabilities in Dipole Plasmas
• The collisional drift wave instability in steep density gradient regimes
• Role of wave-particle resonance in turbulent transport in toroidal plasmas
• Comprehensive Gyrokinetic Study of Eigenstate Transitions in Fast Ion-Driven Electrostatic Drift Instabilities