Effect of Separated Spin Densities of Electrons on the Propagation Characteristics of Kinetic Alfvenic Solitons

Abstract

This study investigates how spin polarization, arising from spin mismatch between electron populations, influences the propagation of kinetic Alfvén waves (KAWs) in a low-beta electron-ion plasma. By analyzing the impact of spin-polarized electron densities in distinct spin states, the research examines modifications to wave dispersion in both linear and nonlinear regimes. In the linear analysis, the study derives and examines the coupled dispersion relation for two dominant wave modes: one governed by Alfvénic dynamics and the other by acoustic interactions. The findings indicate that spin polarization increases the phase speed in the Alfvénic regime, while a larger spin mismatch significantly reduces the phase speed in the acoustic regime. Additionally, the interplay between perpendicular wave characteristics and ion gyration effects modifies wave dispersion, particularly for shorter wavelengths. The study also highlights the role of wave propagation direction in shaping frequency characteristics. In the nonlinear regime, the evolution of KAWs is analyzed using the Reductive Perturbation Technique, leading to a mathematical framework that describes solitary wave structures. The results show that spin polarization suppresses the amplitude and narrows the width of these solitons, while higher electron degeneracy counteracts these effects, contributing to their stabilization. Furthermore, wave obliqueness and the Mach number play a significant role in determining the spatial characteristics and energy distribution of the solitons. These insights provide a deeper understanding of KAW behavior in spin-polarized plasmas, which is relevant to space and astrophysical environments where such conditions prevail.