Search Publications
Magnetic Topology of Actively Evolving and Passively Convecting Structures in the Turbulent Solar Wind
Chapman, S. C.; Hnat, B.; Watkins, N. W.
Multipoint in situ observations of the solar wind are used to identify the magnetic topology and current density of turbulent structures. We find that at least 35% of all structures are both actively evolving and carrying the strongest currents, actively dissipating, and heating the plasma. These structures are comprised of ∼1 /5 3D plasmoids, ∼3 …
Compressible Magnetohydrodynamic Turbulence in the Earth's Magnetosheath: Estimation of the Energy Cascade Rate Using in situ Spacecraft Data
Sahraoui, F.; Huang, S. Y.; Hadid, L. Z. +1 more
The first estimation of the energy cascade rate |ɛC| of magnetosheath turbulence is obtained using the Cluster and THEMIS spacecraft data and an exact law of compressible isothermal magnetohydrodynamics turbulence. The mean value of |ɛC| is found to be close to 10-13 J m-3 s-1 , at least 2 ord…
Fully Kinetic Simulation of 3D Kinetic Alfvén Turbulence
Grošelj, Daniel; Mallet, Alfred; Jenko, Frank +1 more
We present results from a three-dimensional particle-in-cell simulation of plasma turbulence, resembling the plasma conditions found at kinetic scales of the solar wind. The spectral properties of the turbulence in the subion range are consistent with theoretical expectations for kinetic Alfvén waves. Furthermore, we calculate the local anisotropy…
Coherent Structures and Spectral Energy Transfer in Turbulent Plasma: A Space-Filter Approach
Sorriso-Valvo, L.; Retinò, A.; Califano, F. +1 more
Plasma turbulence at scales of the order of the ion inertial length is mediated by several mechanisms, including linear wave damping, magnetic reconnection, the formation and dissipation of thin current sheets, and stochastic heating. It is now understood that the presence of localized coherent structures enhances the dissipation channels and the …
Biermann-Battery-Mediated Magnetic Reconnection in 3D Colliding Plasmas
Fox, W.; Bhattacharjee, A.; Germaschewski, K. +5 more
Recent experiments have demonstrated magnetic reconnection between colliding plasma plumes, where the reconnecting magnetic fields were self-generated in the plasma by the Biermann-battery effect. Using fully kinetic 3D simulations, we show the full evolution of the magnetic fields and plasma in these experiments, including self-consistent magneti…
Observational Test for a Random Sweeping Model in Solar Wind Turbulence
Glassmeier, K. H.; Narita, Y.; Perschke, C. +1 more
Evidence of frequency broadening at ion kinetic scales due to large-scale eddies and waves is found in solar wind turbulence by a test for a random sweeping model using the magnetic energy spectrum in the frequency vs wave number domain in the comoving frame of the flow obtained from multispacecraft observations. The statistical analysis of the fr…
Nonlinear Waves in the Terrestrial Quasiparallel Foreshock
Nakariakov, V. M.; Hnat, B.; Kolotkov, D. Y. +2 more
We provide strongly conclusive evidence that the cubic nonlinearity plays an important part in the evolution of the large amplitude magnetic structures in the terrestrial foreshock. Large amplitude nonlinear wave trains at frequencies above the proton cyclotron frequency are identified after nonharmonic slow variations are filtered out by applying…
Excitation of Chirping Whistler Waves in a Laboratory Plasma
Bortnik, J.; Thorne, R. M.; Van Compernolle, B. +3 more
Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibit…
Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
Kunz, Matthew W.; Schekochihin, Alexander A.; Stone, James M.
Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear S. For a decreasing field, it is found that mostly oblique firehose fluctuations grow at ion Larmor scales and saturate with energies …
Čerenkov Emission of Quasiparallel Whistlers by Fast Electron Phase-Space Holes during Magnetic Reconnection
Eastwood, J. P.; Andersson, L.; Goldman, M. V. +6 more
Kinetic simulations of magnetotail reconnection have revealed electromagnetic whistlers originating near the exhaust boundary and propagating into the inflow region. The whistler production mechanism is not a linear instability, but rather is Čerenkov emission of almost parallel whistlers from localized moving clumps of charge (finite-size quasipa…