Dynamics of EMIC Waves in Multi-Ion Plasmas: The Role of Beam Velocity and Kappa Distributions

Abstract

The influence of beam velocity and the kappa distribution function on the growth length of electromagnetic ion cyclotron (EMIC) waves in a multi-ion magnetoplasma is analyzed. EMIC waves, characterized by their transverse nature and frequencies below the proton cyclotron frequency, play a vital role in various space plasma phenomena and laboratory plasma environments. The kappa distribution function (k_p), which accounts for non-Maxwellian plasma characteristics with an enhanced high-energy particle tail, is used to model the energy distribution of plasma particles more realistically. We conduct a comprehensive analysis of the nonlinear variation in growth length as a function of wave vector for different beam velocities (V_Dl) and the parameter \({{k}_{p}}\), focusing on a plasma composed of multiple ion species such as H⁺, He⁺, and O⁺. Our results reveal that increasing negative beam velocities significantly enhance the growth length of EMIC waves, indicating stronger beam-driven instabilities and wave–particle interactions. Additionally, the growth length rises exponentially with increasing wave vector, particularly at higher beam velocities. The parameter \({{k}_{p}}\) exerts a damping effect, where higher values reduce the growth length, suggesting a potential mechanism for controlling wave growth and stabilizing plasma systems. The study also examines how the \({{k}_{p}}\) modifies the dispersion relations, growth rates, and resonance conditions of EMIC waves. The non-Maxwellian energy distribution influences the overall wave behavior, along with the kappa distribution high-energy tail intensifying wave–particle interactions and contributing to the dynamics of wave growth. These findings have significant implications for understanding and controlling plasma instabilities in fusion devices, particle accelerators, and magnetospheric environments. They enhance the modeling of space weather phenomena and provide deeper insight into the interaction between beam velocity and non-Maxwellian plasma distributions, offering valuable contributions to the field of plasma physics and space plasma dynamics.