PHYSICS OF PLASMAS 22 (2015) ARTN 053102
JOURNAL OF INSTRUMENTATION 10 (2015) ARTN P04010
Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.
Proceedings of the National Academy of Sciences of the United States of America 112 (2015) 8211-8215
The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.
Journal of Plasma Physics 81 (2015)
© 2014 Cambridge University Press.A linearised kinetic equation describing electrostatic perturbations of a Maxwellian equilibrium in a weakly collisional plasma forced by a random source is considered. The problem is treated as a kinetic analogue of the Langevin equation and the corresponding fluctuation-dissipation relations are derived. The kinetic fluctuation-dissipation relation reduces to the standard fluid one in the regime where the Landau damping rate is small and the system has no real frequency; in this case the simplest possible Landau-fluid closure of the kinetic equation coincides with the standard Langevin equation. Phase mixing of density fluctuations and emergence of fine scales in velocity space is diagnosed as a constant flux of free energy in Hermite space; the fluctuation-dissipation relations for the perturbations of the distribution function are derived, in the form of a universal expression for the Hermite spectrum of the free energy. Finite-collisionality effects are included. This work is aimed at establishing the simplest fluctuation-dissipation relations for a kinetic plasma, clarifying the connection between Landau and Hermite-space formalisms, and setting a benchmark case for a study of phase mixing in turbulent plasmas.
ASTROPHYSICAL JOURNAL 807 (2015) ARTN 46
ASTRONOMY & ASTROPHYSICS 576 (2015) ARTN A80
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 452 (2015) 1502-1518
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 454 (2015) 2736-2753
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2015) ARTN 052
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 48 (2015) ARTN 224004
Identification of globular cluster stars in RAVE data - I. Application to stellar parameter calibration
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 451 (2015) 1229-1246
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 450 (2015) 4184-4197
Editorial Special issue: Macroscopic randomness in astrophysical plasmas: The legacy and vision of Ya. B. Zeldovich
JOURNAL OF PLASMA PHYSICS 81 (2015) ARTN 391810403
Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data
PHYSICAL REVIEW D 91 (2015) ARTN 072004
PLASMA PHYSICS AND CONTROLLED FUSION 57 (2015) ARTN 125006
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 447 (2015) 2181-2197
ASTROPHYSICAL JOURNAL 806 (2015) ARTN 117
NEW JOURNAL OF PHYSICS 17 (2015) ARTN 083051