Macroscopic quasi‐linear theory and particle‐in‐cell simulation of helium ion anisotropy instabilities

Abstract

The protons and helium ions in the solar wind are observed to possess anisotropic temperature profiles. The anisotropy appears to be limited by various marginal instability conditions. One of the efficient methods to investigate the global dynamics and distribution of various temperature anisotropies in the large‐scale solar wind models may be that based upon the macroscopic quasi‐linear approach. The present paper investigates the proton and helium ion anisotropy instabilities on the basis of the quasi‐linear theory versus particle‐in‐cell simulation. It is found that the overall dynamical development of the particle temperatures is quite accurately reproduced by the macroscopic quasi‐linear scheme. The wave energy development in time, however, shows somewhat less restrictive comparisons, indicating that while the quasi‐linear method is acceptable for the particle dynamics, the wave analysis probably requires higher‐order physics, such as wave‐wave coupling or nonlinear wave‐particle interaction.

Saturation Characteristics of Parallel EMIC Waves in the Inner Magnetosphere

“…Note that in this stage He + have become anisotropy and might excite He + band EMIC waves (cf. Figure d), which are similar with those circumstances considered in Yoon et al (). In their studies, both H + and He + are assumed to be of one component and anisotropy initially, which might be more suitable for solar wind particles.…”

A Quasi-linear Diffusion Model for Resonant Wave–Particle Instability in Homogeneous Plasma

“…In these models, quasi-linear diffusion coefficients determine the diffusion rate of the resonant particles (Lyons et al 1971;Lyons 1974;Albert 2004;Glauert & Horne 2005;Summers 2005;Isenberg & Vasquez 2011;Tang et al 2020). Alternatively, quasi-linear diffusion models based on a bi-Maxwellian VDF, in which only its moments evolve in time, describe the effective evolution of particle VDFs under the action of microinstabilities Yoon et al 2015Yoon et al , 2017Yoon 2017). Moreover, fully nonlinear simulations based on kinetic theory model the evolution of the particle VDF consistently with predictions from quasi-linear theory (Vocks & Mann 2003;Vocks et al 2005;Gary et al 2008;Saito et al 2008Saito et al , 2010Saito & Peter Gary 2012).…”

Simulation and quasilinear theory of aperiodic ordinary mode instability

“…We have recently begun a comprehensive task of verification of quasilinear theory by comparison with PIC code simulation. 25,26,31 The present work is another addition along such efforts.…”