How Alfv\xe9n waves induce compressive flows in the neighborhood of a 2.5D magnetic null-point

S Sabri,S Poedts,S Vasheghani Farahani,H Ebadi

doi:10.1038/s41598-020-70995-y

S Sabri, S Poedts + Show 2 more

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https://doi.org/10.1038/s41598-020-70995-y

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Abstract

The aim of the present study is to provide insight on the induced compressive perturbations together with the modifications of the environmental parameters in the course of Alfvén wave interaction with a solar magnetic null-point. The shock-capturing Godunov-type code PLUTO is used to solve the set of ideal magnetohydrodynamic equations. The nonlinear effects connected with an initial Alfvén pulse nearing a magnetic null point induces fast and slow magnetoacoustic waves with anti phase conduct. The induced current density and flows are independent of the local plasma-beta at the reconnection site. The induced inflows and outflows highly depend on the polarization. The inflows have a stronger effect compared to the outflows in both the x and y directions showing its peak in the x-direction. The dominant wave that couples to flows is the fast wave due to the in-phase harmony between perturbations of the compressive parameters and the fast wave. The induced current density possesses a steady orientation at the reconnection site which governs the diffusion or propagation of the waves. Induced perturbations by the nonlinear forces together with their back reaction on the Alfvén wave have a significant role in the current density excitation being responsible for the creation of inflows and outflows that are possible candidates for the creation of solar jets which has a significant contribution towards coronal seismology.

Highlights

The Alfvén wave features itself in all aspects of plasma physics
The succeeding sections are to shed light on the induced fast and slow magnetoacoustic waves together with the induced flows and perturbations of the physical variables which results in modifying the plasma parameters of the reconnection site, where a brief discussion is presented regarding the evolution of the plasma characteristics which contribute towards coronal seismology
The numerical simulations are based on the nonlinear MHD theory carried out by the PLUTO code

Summary

Introduction

The Alfvén wave features itself in all aspects of plasma physics. The significance of the Alfvén wave roots in its nature where out of all the mgnatohydrodynamic (MHD) waves it is the only wave that in the linear regime does not perturb the plasma density and the neighboring sites. The succeeding sections are to shed light on the induced fast and slow magnetoacoustic waves together with the induced flows and perturbations of the physical variables which results in modifying the plasma parameters of the reconnection site, where a brief discussion is presented regarding the evolution of the plasma characteristics which contribute towards coronal seismology. It is very probable for a magnetic null point to encounter MHD waves of all kinds.

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