Effect of turbulence on electron cyclotron current drive and heating in ITER

TL;DR

This study uses gyrokinetic turbulence simulations to analyze how electromagnetic fluctuations affect electron transport and heating in ITER, revealing significant impacts on electron current drive and energy deposition.

Contribution

It provides new insights into the role of micro-tearing modes and electromagnetic turbulence in electron transport in ITER's H-mode scenario.

Findings

Particle diffusivity for resonant electrons < 0.15 m^2/s

Heat conductivity for resonant electrons < 2 m^2/s

Electromagnetic fluctuations significantly influence electron transport

Abstract

Non-linear local electromagnetic gyrokinetic turbulence simulations of the ITER standard scenario H-mode are presented for the q=3/2 and q=2 surfaces. The turbulent transport is examined in regions of velocity space characteristic of electrons heated by electron cyclotron waves. Electromagnetic fluctuations and sub-dominant micro-tearing modes are found to contribute significantly to the transport of the accelerated electrons, even though they have only a small impact on the transport of the bulk species. The particle diffusivity for resonant passing electrons is found to be less than 0.15 m^2/s, and their heat conductivity is found to be less than 2 m^2/s. Implications for the broadening of the current drive and energy deposition in ITER are discussed.