Isotopic dependence of impurity transport driven by ion temperature gradient turbulence

TL;DR

This study uses gyrokinetic theory to analyze how different hydrogen isotopes influence impurity transport driven by ion temperature gradient turbulence in plasmas, revealing isotope-dependent variations in impurity flux and accumulation.

Contribution

It provides the first detailed analysis of isotopic effects on impurity transport driven by ITG turbulence, highlighting how isotope changes affect impurity flux and peaking factors.

Findings

Outward impurity flux decreases from hydrogen to tritium for certain impurities.

Isotopic effects significantly influence impurity flux of fully ionized carbon.

High-Z tungsten impurity accumulation is reduced by isotopic effects, especially under stronger magnetic shear.

Abstract

Hydrogenic ion mass effects, namely the isotopic effects on impurity transport driven by ion temperature gradient (ITG) turbulence are investigated using gyrokinetic theory. For non-trace impurities, changing from hydrogen (H) to deuterium (D), and to tritium (T) plasmas, the outward flux for lower (higher) ionized impurities or for lighter (heavier) impurities is found to decrease (increase), although isotopic dependence of ITG linear growth rate is weak. This is mainly due to the decrease of outward (inward) convection, while the isotopic dependence of diffusion is relatively weak. In addition, the isotopic effects reduce (enhance) the impurity flux of fully ionized carbon (C6+) for weaker (stronger) magnetic shear. In trace impurity limit, the isotopic effects are found to reduce the accumulation of high-Z tungsten (W). Moreover, the isotopic effects on the peaking factor (PF) of trace high-Z W get stronger with stronger magnetic shear.