Scaling law of plasma turbulence with nonconservative fluxes

Abstract. Wavevector anisotropy of ion-scale plasma turbulence is studied at various values of ion beta. Two complementary methods are used. One is multi-point measurements of magnetic field in the near-Earth solar wind as provided by the Cluster spacecraft mission, and the other is hybrid numerical simulation of two-dimensional plasma turbulence. Both methods demonstrate that the wavevector anisotropy is reduced with increasing values of ion beta. Furthermore, the numerical simulation study shows the existence of a scaling law between ion beta and the wavevector anisotropy of the fluctuating magnetic field that is controlled by the thermal or hybrid particle-in-cell simulation noise. Likewise, there is weak evidence that the power-law scaling can be extended to the turbulent fluctuating cascade. This fact can be used to construct a diagnostic tool to determine or to constrain ion beta using multi-point magnetic field measurements in space.

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Isotropy restoration toward high-beta space plasmas

Nonlinear Processes in Geophysics Discussions ◽

10.5194/npgd-1-1313-2014 ◽

2014 ◽

Vol 1 (2) ◽

pp. 1313-1330

Author(s):

H. Comişel ◽

Y. Narita ◽

U. Motschmann

Keyword(s):

Magnetic Field ◽

Numerical Simulation ◽

Scaling Law ◽

Field Measurements ◽

Plasma Turbulence ◽

Space Plasmas ◽

Two Dimensional ◽

Magnetic Field Measurements ◽

Spacecraft Mission ◽

High Beta

Abstract. Wavevector anisotropy of ion-scale plasma turbulence is studied at various values of beta. Two complementary methods are used. One is multi-point measurements of magnetic field in the near-Earth solar wind as provided by the Cluster spacecraft mission, and the other is hybrid numerical simulation of two-dimensional plasma turbulence. The both methods provide evidence of wavevector anisotropy as a function of beta such that isotropy is gradually restored toward higher values of beta. Furthermore, the numerical simulation study demonstrates the existence of scaling law between plasma beta and wavevector anisotropy. This fact can be used to construct a diagnostic tool to determine or to constrain plasma beta using multi-point magnetic field measurements in space.

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