Dmitri Yu. Klimushkin

The propagation of high-m Alfvén waves in the earth's magnetosphere and their interaction with high-energy particles

This paper is devoted to the study of Alfven waves generated by the bounce-drift resonance. The global structure of such waves is investigated with due regard to the curvature of field lines, the plasma nonuniformity along field lines and across magnetic shells, finite plasma pressure, and the interaction of the waves with the ionosphere. It is shown that the wave is enhanced as it propagates across magnetic shells with a growth rate dependent on the radial coordinate: The growth rate is maximal on the poloidal surface (i.e., on the magnetic shell, on which the oscillations have a poloidal character), and it decreases to zero on the toroidal surface (where the oscillations have a toroidal character). However, the amplitude maximum does not coincide with the poloidal surface; it is shifted toward the toroidal surface. Moreover, when the value of the growth rate due to the driving particles increases on the poloidal surface, the amplitude maximum of the wave is shifted toward the toroidal surface.

The Alfvén mode gyrokinetic equation in finite-pressure magnetospheric plasma

The paper is concerned with the derivation of the Alfven mode equation in finite-pressure space plasma in gyrokinetic approach. The long plasma approximation is used, where the bounce frequency is much lower than both wave and drift frequencies. The only ultralow frequency mode in the long plasma approximation is the Alfven-ballooning compressional mode, which is described by the Alfvenic dispersion relation with some additional (ballooning) terms caused by the field line curvature and plasma pressure effects. Due to these effects the Alfven mode acquires also considerable parallel magnetic field component. The long plasma approximation allowed us to consider the correspondence between the gyrokinetic and MHD approaches for the Alfven mode equation. It is shown that in 0 < β ≪ 1 case, MHD approach gives correct Alfven wave description, where β is plasma to magnetic pressure ratio.

The structure of low-frequency standing Alfvén waves in the box model of the magnetosphere with magnetic field shear

The paper is concerned with the influence of magnetic field shear on the structure of Alfven waves standing along field lines in the one-dimensionally inhomogeneous box model of the magnetosphere, enclosed between two parallel, infinitely conducting planes (ionospheres). We consider the transverse small-scale Alfven waves whose azimuthal component of the wave vector

Azimuthally small-scale Alfvén waves in magnetosphere excited by the source of finite duration

k_y

Two kinds of mirror modes in a nonzero electron-temperature plasma

satisfies the condition

ULF waves at Mercury: Earth, the giants, and their little brother compared

k_y l\,{\gg}\,1

Concerning ULF pulsations in Mercury's magnetosphere

, where

Spatial structure and stability of coupled Alfven and drift compressional modes in non-uniform magnetosphere: Gyrokinetic treatment

l

Theory of azimuthally small-scale Alfven waves in an axisymmetric magnetosphere with small but finite plasma pressure

is the distance between the ionospheres. For this model, the Alfven resonance condition has been established. It is shown that resonance can also occur at a constant Alfven velocity if the field-line inclination to the ionosphere is changed. On resonant magnetic shells there occurs a singularity of the wave field of the same kind as in the absence of shear. Moreover, there are found many resemblances between Alfven-wave behavior in our one-dimensionally inhomogeneous model and in two-dimensional inhomogeneous models with plasma and magnetic field parallel inhomogeneity taken into account. Thus, the presence of shear leads to a difference of the frequencies of poloidal and toroidal oscillations of field lines, and to the dependence of the waves frequency on the transversal components of wave vector. Then, in the sheared magnetic field with highly conductive boundaries the source excites multiple standing Alfven harmonics at different locations. In general, the localization regions of different longitudinal harmonics overlap. However, in the small but finite shear limit, a total wave field represents a set of mutually isolated transparent regions corresponding to different harmonic numbers. In each of these regions the waves are found to be travelling across the magnetic shells, and the transparent region is limited in the coordinate

SuperDARN observations of high‐m ULF waves with curved phase fronts and their interpretation in terms of transverse resonator theory

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