相关论文: Nonlinear Alfv\'en wave dynamics at a 2D magnetic …
Context: MHD waves and magnetic null points are both prevalent in many astrophysical plasmas, including the solar atmosphere. Interaction between waves and null points has been implicated as a possible mechanism for localised heating…
We investigate the behaviour of nonlinear, nonideal Alfv\'en wave propagation within an inhomogeneous magnetic environment. The governing MHD equations are solved in 1D and 2D using both analytical techniques and numerical simulations. We…
Where spatial gradients in the amplitude of an Alfven wave are non-zero, a nonlinear magnetic-pressure gradient acts upon the medium (the ponderomotive force). We investigate the nature of such a force in inhomogeneous 2.5D MHD plasmas by…
Context: Coronal magnetic null points have been implicated as possible locations for localised heating events in 2D models. We investigate this possibility about fully 3D null points. Aims: We investigate the nature of the fast…
Large-amplitude Alfv\'en waves are observed in various systems in space and laboratories, demonstrating an interesting property that the wave shapes are stable even in the nonlinear regime. The ideal magnetohydrodynamics (MHD) model…
We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfven…
We study the nonlinear evolution of very oblique small-scale Alfv\'en waves with $k_\perp d_i\gtrsim 1$. At these scales, the waves become significantly compressive, unlike in MHD, due to the Hall term in the equations. We demonstrate that…
In the approximation of linear dissipative magnetohydrodynamics (MHD) it can be shown that driven MHD waves in magnetic plasmas with high Reynolds number exhibit a near resonant behaviour if the frequency of the wave becomes equal to the…
This paper is the third in a series of investigations by the authors. The nature of fast magnetoacoustic and Alfv\'en waves is investigated in a 2D $\beta=0$ plasma in the neighbourhood of two dipoles. We use both numerical simulations…
We consider the ideal magnetohydrodynamics (MHD) subjected to a strong magnetic field along $x_1$ direction in three-dimensional thin domains $\Omega_\delta=\mathbb{R}^2\times(-\delta,\delta)$ with slip boundary conditions. It is well-known…
Large-amplitude Alfv\'en waves are ubiquitous in space plasmas and a main component of magnetohydrodynamic (MHD) turbulence in the heliosphere. As pump waves they are prone to parametric instability by which they can generate cyclotron and…
Complete asymptotic expansions are developed for slow, Alfv\'en and fast magnetohydrodynamic waves at the base of an isothermal three-dimensional (3D) plane stratified atmosphere. Together with existing convergent Frobenius series solutions…
The interaction of a weakly nonlinear Alfv\'enic pulse with an Alfv\'en speed inhomogeneity in the direction perpendicular to the magnetic field is investigated. Identically to the phase mixing experienced by a harmonic Alfv\'en wave, sharp…
Non-uniformity plays an important role for MHD waves. For a uniform plasma of infinite extent the MHD waves can be subdivided in two classes with distinct properties. The first class contains the Alfv\'en waves. The Alfv\'en waves are…
The propagation of linear Alfv\'en wave pulses in an inhomogeneous plasma near a 2D coronal null point is investigated. When a uniform plasma density is considered, it is seen that an initially planar Alfv\'en wavefront remains planar,…
We investigate the viability of MHD waves, in particular acoustic p-modes, in causing strong current accumulation at the null points. We begin with a three-dimensional numerical setup incorporating a gravitationally stratifed solar…
The magnetic energy of nonlinear Alfven waves in compressible plasmas may be ponderomotively coupled only to ion-acoustic quasi-modes which modulate the wave phase velocity and cause wave-front steepening. In the collisionless plasma with…
The propagation and non-linear interactions of magnetohydrodynamic waves are considered in the force-free limit, where the inertia of the conducting matter which enforces the MHD condition E.B = 0 can be neglected in comparison with the…
We consider a series of MHD simulations in which a small amplitude, transverse velocity perturbation is introduced into a complex magnetic field. We analysed the deformation of the wave fronts as the perturbation propagates through the…
The large abundance of electrically neutral particles has a remarkable impact on the dynamics of many astrophysical plasmas. Here, we use a two-fluid model that includes charge-neutral elastic collisions and Hall's current to study the…