A self-organized criticality model for ion temperature gradient (ITG) mode driven turbulence in confined plasma

TL;DR

This paper introduces a Cellular Automaton model for ion temperature gradient driven turbulence in fusion plasmas, capturing self-organized criticality and reproducing key experimental features of plasma behavior.

Contribution

It presents a novel SOC model based on physical ion temperature variables that mimics real plasma processes and reproduces observed turbulence characteristics.

Findings

Ion temperature profiles are exponential and highly stiff.

Heat flux distributions follow power-law shapes.

The model aligns qualitatively with experimental plasma data.

Abstract

A new Self-Organized Criticality (SOC) model is introduced in the form of a Cellular Automaton (CA) for ion temperature gradient (ITG) mode driven turbulence in fusion plasmas. Main characteristics of the model are that it is constructed in terms of the actual physical variable, the ion temperature, and that the temporal evolution of the CA, which necessarily is in the form of rules, mimics actual physical processes as they are considered to be active in the system, i.e. a heating process and a local diffusive process that sets on if a threshold in the normalized ion temperature gradient R/L_T is exceeded. The model reaches the SOC state and yields ion temperature profiles of exponential shape, which exhibit very high stiffness, in that they basically are independent of the loading pattern applied. This implies that there is anomalous heat transport present in the system, despite the fact that diffusion at the local level is imposed to be of a normal kind. The distributions of the heat fluxes in the system and of the heat out-fluxes are of power-law shape. The basic properties of the model are in good qualitative agreement with experimental results.