Analysis of Lithium Driven Electron Density Peaking in FTU Liquid Lithium Limiter Experiments

TL;DR

This study investigates how lithium impurities influence electron density peaking in FTU Liquid Lithium Limiter experiments, revealing lithium's role in reducing outward electron flux and promoting inward deuterium transport.

Contribution

It provides a detailed non-linear gyrokinetic and fluid analysis of lithium's effect on microstability and turbulent transport in tokamak core plasmas.

Findings

Lithium profile reduces outward electron flux.

Lithium causes inward turbulent deuterium transport.

Centrally peaked lithium enhances electron density peaking.

Abstract

The impact of lithium impurities on the microstability and turbulent transport characteristics in the core of a typical FTU Liquid Lithium Limiter (LLL)(Mazzitelli et al., Nucl. Fusion, 2011) discharge during the density ramp-up phase is studied. A non-linear gyrokinetic analysis performed with GKW (Peeters et al.,Comp. Phys. Comm., 2009) accompanied by a quasi-linear fluid analysis is presented. We show that a centrally peaked, high concentration lithium profile contributes to the electron peaking by reducing the outward electron flux, and that it leads to inward turbulent deuterium transport through ion flux separation.