Integrated modelling and multiscale gyrokinetic validation study of ETG turbulence in a JET hybrid H-mode scenario

TL;DR

This study uses integrated and multiscale gyrokinetic simulations to investigate electron temperature gradient turbulence in a JET hybrid H-mode scenario, challenging previous simplified models and providing detailed validation of turbulence behavior.

Contribution

It offers a comprehensive validation of ETG turbulence predictions using high-fidelity multiscale gyrokinetic simulations, refuting earlier simplified assumptions.

Findings

Ion-scale turbulence matches power balance fluxes within error margins.

Multiscale simulations show no significant ETG heat flux.

Simple rules-of-thumb are inadequate for predicting ETG onset.

Abstract

Previous studies with first-principle-based integrated modelling suggested that ETG turbulence may lead to an anti-GyroBohm isotope scaling in JET high-performance hybrid H-mode scenarios. A dedicated comparison study against higher-fidelity turbulence modelling invalidates this claim. Ion-scale turbulence with magnetic field perturbations included, can match the power balance fluxes within temperature gradient error margins. Multiscale gyrokinetic simulations from two distinct codes produce no significant ETG heat flux, demonstrating that simple rules-of-thumb are insufficient criteria for its onset.