Energy exchange between electrons and ions driven by ITG-TEM turbulence

TL;DR

This paper investigates how energy is exchanged between electrons and ions in ITG-TEM turbulence using gyrokinetic simulations, revealing the dominant transfer directions and validating predictive models.

Contribution

It provides new insights into the energy exchange mechanisms in ITG-TEM turbulence and introduces a novel correlation-based method for predicting energy transfer.

Findings

Energy flows from electrons to ions in TEM turbulence.

The direction of energy exchange depends on the relative magnitudes of parallel heating and perpendicular cooling.

A correlation-based method effectively predicts energy exchange.

Abstract

In this study, the energy exchange between electrons and ions in ITG TEM turbulence is investigated using gyrokinetic simulations. The energy exchange in TEM turbulence is primarily composed of the cooling of electrons associated with perpendicular drift and the heating of ions moving parallel to magnetic field lines. TEM turbulence facilitates energy transfer from electrons to ions, which is opposite to the direction observed in ITG turbulence. In mixed ITG TEM turbulence, the relative magnitudes of parallel heating and perpendicular cooling for each species determine the overall direction and magnitude of energy exchange. From the viewpoint of entropy balance, it is further confirmed that energy flows from the species with larger entropy production, caused by particle and heat fluxes, to the other species in ITG TEM turbulence. The predictability of turbulent energy exchange in ITG-TEM turbulence by the quasilinear model is examined. In addition, an alternative method based on the correlation between energy flux and energy exchange is developed, and its validity is demonstrated.