A minimally constrained model of self-organized helical states in reversed-field pinches

TL;DR

This paper presents a simplified equilibrium model that reproduces self-organized helical states in reversed-field pinches using only five parameters, capturing key topological features and transport phenomena observed experimentally.

Contribution

It introduces a minimally constrained model that accurately reproduces SHAx and DAx states, reducing complexity and preserving topological structures.

Findings

Successfully reproduces SHAx and DAx states with minimal parameters

Shows transport barrier formation explains self-organization

Captures topological features of plasma states

Abstract

We show that the self-organized single-helical-axis (SHAx) and double-helical-axis (DAx) states in reversed field pinches can be reproduced in a minimally constrained equilibrium model using only five parameters. This is a significant reduction on previous representations of the SHAx which have required an infinite number of constraints. The DAx state, which has a non-trivial topology, has not been previously reproduced using an equilibrium model that preserves this topological structure. We show that both states are a consequence of transport barrier formation in the plasma core, in agreement with experimental results.