Effects of magnetic drifts on ion transport in turbulent tokamak plasmas

TL;DR

This study investigates how magnetic drifts influence ion transport in turbulent tokamak plasmas, revealing that turbulence and magnetic effects can both enhance and suppress ion diffusion depending on specific parameters.

Contribution

It introduces a detailed analysis of magnetic drift effects on ion transport using the Decorrelation Trajectory Method in realistic turbulence models.

Findings

Magnetic drifts can significantly alter ion transport, increasing or decreasing diffusion.

Trajectory trapping is identified as the main cause of anomalous diffusion.

Transport regimes depend on turbulence parameters and trapping conditions.

Abstract

The stochastic advection of low energy deuterium ions is studied in a three dimensional realistic turbulence model in conditions relevant for current tokamak fusion experiments. The diffusion coefficients are calculated starting from the test particles trajectories in the framework of the semi-analitical statistical model called the Decorrelation Trajectory Method. We show that trajectory trapping determined by the space correlation of the velocity field is the main cause for anomalous diffusion and we obtain the transport regimes corresponding to different values of the parameters of the turbulence model and a trapping condition in the limit of frozen turbulence. Depending on the value of the parameters of the model, the interaction between turbulence and magnetic drifts leads to both an increase (with transport in the poloidal direction increasing up to an order of magnitude) and a decrease of the particle transport.