Relaxation models for Single Helical reversed field pinch plasmas at low aspect ratio

TL;DR

This paper investigates the relaxation processes in low aspect ratio single helical reversed field pinch plasmas, validating a theoretical model against experimental data from the RELAX device to understand mode scaling.

Contribution

It compares and validates a relaxation-based theoretical model with experimental data for low aspect ratio RFP plasmas, extending understanding of mode behavior.

Findings

The dominant mode number aligns with relaxation theory predictions.

Experimental data supports the model's applicability at low aspect ratios.

Insights into mode scaling in low aspect ratio plasmas are provided.

Abstract

A recent study [1] about the scaling with the aspect ratio (i.e. the ratio between the major and minor radius of the torus) of the dominant mode in Single Helical (SH) Reverse Field Pinch (RFP) plasmas has shown, at intermediate aspect ratio, that the dominant toroidal mode number in the helical states can be interpreted as the result of a relaxation process. In this work, the theoretical model is compared and validated with the experimental data obtained in the low aspect ratio RELAX device [2]. [1] R. Paccagnella, Phys. of Plasmas 23 (2016) 092512. [2] S. Masamune et al, J. Phys. Soc. Japan 76 ( 2007) 123501.