Search Publications
Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind
Sorriso-Valvo, Luca; Verscharen, Daniel; Chen, Christopher H. K. +5 more
Where and under what conditions the transfer of energy between electromagnetic fields and particles takes place in the solar wind remains an open question. We investigate the conditions that promote the growth of kinetic instabilities predicted by linear theory to infer how turbulence and temperature-anisotropy-driven instabilities are interrelate…
Efficient kinetic Lattice Boltzmann simulation of three-dimensional Hall-MHD turbulence
Telloni, Daniele; Marino, Raffaele; Foldes, Raffaello +4 more
Simulating plasmas in the Hall-magnetohydrodynamics (Hall-MHD) regime represents a valuable approach for the investigation of complex nonlinear dynamics developing in astrophysical frameworks and fusion machines. The Hall electric field is computationally very challenging as it involves the integration of an additional term, proportional to \nabla…
An approximate analytic solution to the coupled problems of coronal heating and solar-wind acceleration
Chandran, Benjamin D. G.
Between the base of the solar corona at $r=r_\textrm {b}$ and the Alfvén critical point at $r=r_\textrm {A}$, where $r$ is heliocentric distance, the solar-wind density decreases by a factor $ \mathop > \limits_∼ 10^5$, but the plasma temperature varies by a factor of only a few. In this paper, I show that such quasi-isothermal evolution out to…
Collisions of acoustic solitons and their electric fields in plasmas at critical compositions
Verheest, Frank; Hereman, Willy A.
Acoustic solitons obtained through a reductive perturbation scheme are normally governed by a Korteweg-de Vries (KdV) equation. In multispecies plasmas at critical compositions the coefficient of the quadratic nonlinearity vanishes. Extending the analytic treatment then leads to a modified KdV (mKdV) equation, which is characterized by a cubic non…
Interplay between Kelvin-Helmholtz and lower-hybrid drift instabilities
Henri, Pierre; Pucci, Francesco; Lavorenti, Federico +3 more
Boundary layers in space and astrophysical plasmas are the location of complex dynamics where different mechanisms coexist and compete, eventually leading to plasma mixing. In this work, we present fully kinetic particle-in-cell simulations of different boundary layers characterized by the following main ingredients: a velocity shear, a density gr…
How non-stationary are moderately supercritical shocks?
Gedalin, Michael
Ion motion in a collisionless shock front is affected by macroscopic large-scale weakly varying and microscopic small-scale fast varying magnetic and electric fields. With the increase of the Mach number the role of the microscopic field is expected to become progressively more important. Using a combination of hybrid simulations and test particle…
Reduced magneto-hydrodynamic theory of coherent magnetic chains in the solar wind
Alexandrova, Olga; Maksimović, Milan; Jovanović, Dušan +1 more
An analytic theory is presented of magnetic structures in collisionless, high-β plasmas. Using a reduced magnetohydrodynamic model, a stationary nonlinear solution is constructed in the form of a Kelvin-Stuart cat's eyes chain of magnetic islands, on the spatial scale that exceeds the characteristic ion lengths. The solution is imbedded in a backg…
Finite-Larmor-radius equilibrium and currents of the Earth's flank magnetopause
Cerri, S. S.
We consider the one-dimensional equilibrium problem of a shear-flow boundary layer within an `extended-fluid model' of a plasma that includes the Hall and the electron pressure terms in Ohm's law, as well as dynamic equations for anisotropic pressure for each species and first-order finite-Larmor-radius (FLR) corrections to the ion dynamics. We pr…
Diagnosing collisionless energy transfer using field-particle correlations: gyrokinetic turbulence
Klein, Kristopher G.; Howes, Gregory G.; Tenbarge, Jason M.
Determining the physical mechanisms that extract energy from turbulent fluctuations in weakly collisional magnetized plasmas is necessary for a more complete characterization of the behaviour of a variety of space and astrophysical plasmas. Such a determination is complicated by the complex nature of the turbulence as well as observational constra…
Magnetized Kelvin-Helmholtz instability: theory and simulations in the Earth's magnetosphere context
Califano, Francesco; Faganello, Matteo
The Kelvin-Helmholtz instability, proposed a long time ago for its role in and impact on the transport properties at magnetospheric flanks, has been widely investigated in the Earth's magnetosphere context. This review covers more than fifty years of theoretical and numerical efforts in investigating the evolution of Kelvin-Helmholtz vortices and …