On radial geodesic forcing of zonal modes

TL;DR

This paper analyzes how geodesic curvature influences the radial behavior of zonal modes in magnetized plasmas, concluding that net radial geodesic forcing cannot occur in closed toroidal configurations and exploring the dynamics of zonal jets and modes.

Contribution

It provides a theoretical analysis of geodesic effects on zonal modes, clarifying the absence of net radial forcing in closed configurations and describing mode propagation characteristics.

Findings

Net radial geodesic forcing of zonal modes is not expected in closed toroidal configurations.

Radial propagation of zonal modes exhibits characteristics similar to second sound in quantum condensates.

Poloidally elongated zonal jets can exhibit radial motion in the presence of geodesic acoustic modes.

Abstract

The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of geodesic acoustic mode activity. Phenomenologically a radial propagation of zonal modes shows some characteristics of a classical analogon to second sound in quantum condensates.