Direct multiscale coupling of a transport code to gyrokinetic turbulence codes

TL;DR

This paper presents a multiscale coupling method that integrates a transport solver with gyrokinetic turbulence codes, significantly reducing computational costs and enabling first-principles simulations of entire fusion devices.

Contribution

It introduces a novel multiscale coupling framework that combines microscopic gyrokinetic turbulence calculations with macroscopic transport models within a unified simulation environment.

Findings

Reduced computational expense by several orders of magnitude.

Simulation results agree with experimental data from JET and ASDEX Upgrade.

First-principles full-device plasma simulations are now feasible.

Abstract

Direct coupling between a transport solver and local, nonlinear gyrokinetic calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, Ph.D. thesis, arxiv:0901.2868] is described. The coupling of the microscopic and macroscopic physics is done within the framework of multiscale gyrokinetic theory, of which we present the assumptions and key results. An assumption of scale separation in space and time allows for the simulation of turbulence in small regions of the space-time grid, which are embedded in a coarse grid on which the transport equations are implicitly evolved. This leads to a reduction in computational expense of several orders of magnitude, making first-principles simulations of the full fusion device volume over the confinement time feasible on current computing resources. Numerical results from TRINITY simulations are presented and compared with experimental data from JET and ASDEX Upgrade plasmas.