# Interplay of transitions between oscillations with emergence of fireballs and quantification of phase coherence, scaling index in a magnetized glow discharge plasma of toroidal assembly

## TL;DR

This study investigates the complex oscillatory behaviors and fireball dynamics in a magnetized glow discharge plasma within a toroidal vessel, revealing how magnetic fields influence phase coherence, chaos, and long-range correlations.

## Contribution

It provides a comprehensive analysis of plasma oscillations, fireball evolution, and phase coherence under varying magnetic fields using DFA and phase coherence index, highlighting new insights into plasma dynamics.

## Key findings

- Oscillations transition from regular to chaotic with magnetic field variation.
- Maximum phase coherence occurs in toroidal and mixed magnetic field cases.
- Higher magnetic fields induce long-range persistent behavior in plasma dynamics.

## Abstract

Interplay of transition of floating potential fluctuations in a glow discharge plasma in the toroidal vacuum vessel of SINP tokamak has been observed. With variation in the strength of the vertical and toroidal magnetic fields, regular and inverted relaxation oscillations as well as sinusoidal oscillations are observed with the slow and fast time scale of the relaxation oscillations reversing their nature at a high value of vertical magnetic field strength. However for small value of toroidal magnetic field the transitions follow relaxation $\rightarrow$ chaotic oscillations with the chaotic nature prevailing at higher values of toroidal magnetic field. Evolution of associated anode fireball dynamics under the action of increasing vertical, toroidal as well as increasing vertical field at a fixed toroidal field (mixed field) of different strength has been studied. Estimation of phase coherence index for each case has been carried out to examine the evidence of finite nonlinear interaction. A comprehensive study of the dynamics of the fireball is found to be associated with the values of phase coherence index. The index is found to take maximum values for the case of toroidal, mixed field when there is an existence of power/energy concentration in a large region of frequency band. A detailed study of the scaling region using detrended fluctuation analysis (DFA) by estimating the scaling exponent has been carried out for increasing values of discharge voltage, vertical, toroidal as well as the mixed field (toroidal plus vertical). A persistence long range behaviour associated with the nature of the anode glow has been investigated in case of higher values of toroidal, mixed field whereas increasing DV, vertical magnetic field leads to a perfectly correlated dynamics with values of scaling exponent greater than unity