Predictive power-sharing scaling law in double-null L-mode plasmas

TL;DR

This paper investigates the physical mechanisms behind power sharing in double-null L-mode plasmas, deriving and validating a scaling law through simulations and experimental data that captures the observed asymmetry trends.

Contribution

The study introduces a new analytical scaling law for power-sharing asymmetry in double-null plasmas, validated by simulations and experimental data.

Findings

The power asymmetry is influenced by diamagnetic drift, turbulence, and geometry.

The derived scaling law accurately predicts simulation trends.

Experimental data from TCV discharges confirm the law's validity.

Abstract

The physical mechanisms regulating the power sharing at the outer targets of L-mode double-null (DN) configurations are investigated using nonlinear, flux-driven, three-dimensional two-fluid simulations. Scans of parameters that regulate the turbulent level, such as the plasma resistivity and the magnetic imbalance, reveal that the power asymmetry in DN configurations is determined by the combined effects of diamagnetic drift, turbulence, and geometrical factor. Leveraging these observations, an analytical theory-based scaling law for the power-sharing asymmetry is derived and compared with nonlinear simulations. These comparisons indicate that the scaling law effectively captures the trends observed in simulations. Validation with experimental data from TCV DN discharges demonstrates agreement of the scaling law with the experimental results.