Resistive g-modes in a reversed field pinch plasma

TL;DR

This paper provides the first direct experimental evidence of high-frequency resistive g-modes in the edge region of a reversed field pinch plasma, aligning with theoretical predictions and offering insights into mode saturation.

Contribution

It reports the first direct detection and characterization of high-n resistive g-modes in RFP plasmas, confirming theoretical models and proposing a saturation level model.

Findings

Detection of high-frequency, high-n magnetic fluctuations in RFP edge

Good agreement between observed modes and linear MHD stability theory

Proposal of a simple model for mode saturation levels

Abstract

First direct experimental evidence of high frequency, high toroidal mode number (n>20), magnetic fluctuations due to unstable resistive interchange modes (g-modes) resonant in the edge region of a reversed field pinch (RFP) plasma is presented. Experimental characterization of time and space periodicities of the modes is provided by means of highly resolved in-vessel edge and insertable magnetic diagnostics. It is found that the spectral mode properties are in good agreement with the predictions of the theoretical linear resistive magnetohydrodynamic stability analysis. A simple model is proposed for the observed saturation levels of the modes.