Ion temperature gradient turbulence in helical and axisymmetric RFP plasmas

TL;DR

This study uses gyrokinetic calculations to compare ion temperature gradient turbulence in helical and axisymmetric reversed field pinch plasmas, revealing how magnetic geometry influences turbulence stability and transport.

Contribution

It provides the first systematic linear and nonlinear comparison of ITG turbulence in helical versus axisymmetric RFP configurations, highlighting geometry effects on stability and transport.

Findings

High-current helical state has a lower ITG stability threshold.

ITG turbulence may significantly contribute to heat transport in helical RFPs.

Magnetic geometry impacts zonal flow production and turbulence behavior.

Abstract

Turbulence induced by the ion temperature gradient (ITG) is investigated in the helical and axisymmetric plasma states of a reversed field pinch device by means of gyrokinetic calculations. The two magnetic configurations are systematically compared, both linearly and nonlinearly, in order to evaluate the impact of the geometry on the instability and its ensuing transport, as well as on the production of zonal flows. Despite its enhanced confinement, the high-current helical state demonstrates a lower ITG stability threshold compared to the axisymmetric state, and ITG turbulence is expected to become an important contributor to the total heat transport.