Related papers: Nonlinear Interactions in Spherically Polarized Al…
Motivated by recent Parker Solar Probe (PSP) observations of "switchbacks" (abrupt, large-amplitude reversals in the radial magnetic field, which exhibit Alfv\'enic correlations) we examine the dynamics of large-amplitude Alfv\'en waves in…
The solar wind is a magnetized and turbulent plasma. Its turbulence is often dominated by Alfv\'enic fluctuations and often deemed as nearly incompressible far away from the Sun, as shown by in-situ measurements near 1AU. However, for solar…
We study large-amplitude, very oblique Alfv\'en waves at low $\beta$, with small gradient length scales, comparable to the ion inertial scale $d_i$. Such waves have large density fluctuations, and slight dispersion from finite-frequency and…
This paper summarises some of the recent progress that has been made in understanding astrophysical plasma turbulence in the solar wind, from in situ spacecraft observations. At large scales, where the turbulence is predominantly Alfvenic,…
Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity…
The nonlinear interaction between counterpropagating Alfven waves is the physical mechanism underlying the cascade of energy to small scales in astrophysical plasma turbulence. Beginning with the equations for incompressible MHD, an…
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…
Alfv\'enic turbulence in space is usually imbalanced: amplitudes of waves propagating parallel and anti-parallel to the mean magnetic field $B_0$ are unequal. It is commonly accepted that the turbulence is driven by (counter-)collisions…
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…
Recently, it has been realized that magnetic plasma turbulence and magnetic field reconnection are inherently related phenomena. Turbulent fluctuations generate regions of a sheared magnetic field that become unstable to the tearing…
Recent observations have demonstrated that waves which are capable of carrying large amounts of energy are ubiquitous throughout the solar corona. However, the question of how this wave energy is dissipated (on which time and length scales)…
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 nature of solar wind turbulence at large scale is rather well understood in the theoretical framework of magnetohydrodynamics. The situation is quite different at sub-proton scales where the magnetic energy spectrum measured by…
We present numerical simulations of reduced magnetohydrodynamic (RMHD) turbulence in a magnetic flux tube at the center of a polar coronal hole. The model for the background atmosphere is a solution of the momentum equation, and includes…
Aims: Propagation and energy transfer of torsional Alfv\'en waves in solar magnetic flux tubes of axial symmetry is studied. Methods: An analytical model of a solar magnetic flux tube of axial symmetry is developed by specifying a magnetic…
The cascade of kinetic Alfv\'en waves (KAWs) at the sub-ion scales in the solar wind is numerically simulated using a fluid approach that retains ion and electron Landau damping, together with ion finite Larmor radius corrections. Assuming…
Motivated by recent analytic predictions, we report numerical evidence showing that in driven incompressible magnetohydrodynamic turbulence the magnetic- and velocity-field fluctuations locally tend to align the directions of their…
We discuss properties of large amplitude magnetic field fluctuations during fast Alfvenic solar wind streams, focussing on the statistics of the rotation angle between consecutive magnetic field vector measurements for different scales in…
We investigate the dependence of solar wind fluctuations measured by the Wind spacecraft on scale and on the degree of alignment between oppositely directed Elsasser fields. This alignment controls the strength of the non-linear…
Previous studies have established that a weak-to-strong transition occurs in Alfvenic magnetohydrodynamic (MHD) turbulence as energy cascades from large to small scales. However, the spatiotemporal (frequency-wavenumber) properties of…