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Phys. Rev. Lett. 100, 065004 (2008) [4 pages]

Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas

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G. G. Howes1,*, W. Dorland2, S. C. Cowley3,4, G. W. Hammett5, E. Quataert1, A. A. Schekochihin4, and T. Tatsuno6
1Department of Astronomy, University of California, Berkeley, California 94720, USA
2Department of Physics, CSCAMM, and IREAP, University of Maryland, College Park, Maryland 20742-3511, USA
3Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547, USA
4Plasma Physics, Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom
5Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
6Department of Physics, University of Maryland, College Park, Maryland 20742-3511, USA.

Received 21 November 2007; published 14 February 2008

This Letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale). Magnetic- and electric-field energy spectra show a break at the ion gyroscale; the spectral slopes are consistent with scaling predictions for critically balanced turbulence of Alfvén waves above the ion gyroscale (spectral index -5/3) and of kinetic Alfvén waves below the ion gyroscale (spectral indices of -7/3 for magnetic and -1/3 for electric fluctuations). This behavior is also qualitatively consistent with in situ measurements of turbulence in the solar wind. Our findings support the hypothesis that the frequencies of turbulent fluctuations in the solar wind remain well below the ion cyclotron frequency both above and below the ion gyroscale.

© 2008 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.100.065004
DOI:
10.1103/PhysRevLett.100.065004
PACS:
52.35.Ra, 52.65.Tt, 96.50.Tf

*ghowes@astro.berkeley.edu

See Also

Comment: W. H. Matthaeus, S. Servidio, and P. Dmitruk, Comment on “Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas”, Phys. Rev. Lett. 101, 149501 (2008).

Reply: G. G. Howes, S. C. Cowley, W. Dorland, G. W. Hammett, E. Quataert, A. A. Schekochihin, and T. Tatsuno, Howes et al. Reply:, Phys. Rev. Lett. 101, 149502 (2008).