A study of particle acceleration, heating, power deposition, and the damping length of kinetic Alfvén waves in non-Maxwellian coronal plasma

¹ Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899, USA
² Department of Space Sciences, Institute of Space Technology, Islamabad 44000, Pakistan
³ Space and Astrophysics Research Lab (SARL), National Center of GIS and Space Applications (NCGSA), Islamabad 44000, Pakistan
⁴ General Linear Space Plasma Lab LLC, 4, Foster City, CA 94404, USA
⁵ Center for Astrophysics, Harvard and Smithsonian, Cambridge, MA 02138, USA

^⋆ Corresponding authors; sa0173@uah.edu, syedayaz263@gmail.com

Received: 26 September 2024
Accepted: 22 November 2024

Abstract

Context. The heating of the solar corona and solar wind, particularly through suprathermal particles and kinetic Alfvén waves (KAWs) within the 0–10 R_Sun range, has been a subject of great interest for many decades. This study investigates and explores the acceleration and heating of charged particles and the role of KAWs in the solar corona.

Aims. We investigate how KAWs transport energy and accelerate and heat the charged particles, focusing on the behavior of perturbed electromagnetic (EM) fields, the Poynting flux vectors, net power transfer through the solar flux loop tubes, resonant particles’ speed, group speed, and the damping length of KAWs. The study examines how these elements are influenced by suprathermal particles (κ) and the electron-to-ion temperature ratios (T_e/T_i).

Methods. We used kinetic plasma theory coupled with the Vlasov-Maxwell model to investigate the dynamics of KAWs and particles. We assumed a collisionless, homogeneous, and low-beta electron-ion plasma in which Alfvén waves travel in the kinetic limits; that is, m_e/m_i ≪ β ≪ 1. Furthermore, the plasma incorporates suprathermal high-energy particles, necessitating an appropriate distribution function to accurately describe the system. We adopted the Kappa distribution function as the most suitable choice for our analysis.

Results. The results show that the perturbed EM fields are significantly influenced by κ and the effect of T_e/T_i. We evaluate both the parallel and perpendicular Poynting fluxes and find that the parallel Poynting flux (S_z) dissipates gradually for lower κ values. In contrast, the perpendicular flux (S_x) dissipates quickly over shorter distances. Power deposition in solar flux tubes is significantly influenced by κ and T_e/T_i. We find that particles can heat the solar corona over long distances (R_Sun) in the parallel direction and short distances in the perpendicular direction. The group velocity of KAWs increases for lower κ values, and the damping length, L_G, is enhanced under lower κ, suggesting longer energy transport distances (R_Sun). These findings offer a comprehensive understanding of particle-wave interactions in the solar corona and wind, with potential applications for missions such as the Parker Solar Probe, (PSP), and can also apply to other environments where non-Maxwellian particle distributions are frequently observed.