Variance anisotropy in kinetic plasmas
Parashar, T. N., Oughton, S., Matthaeus, W. H., & Wan, M. (2016). Variance anisotropy in kinetic plasmas. Astrophysical Journal, 824(1). http://doi.org/10.3847/0004-637X/824/1/44
Permanent Research Commons link: https://hdl.handle.net/10289/10561
Solar wind fluctuations admit well-documented anisotropies of the variance matrix, or polarization, related to the mean magnetic field direction. Typically, one finds a ratio of perpendicular variance to parallel variance of the order of 9:1 for the magnetic field. Here we study the question of whether a kinetic plasma spontaneously generates and sustains parallel variances when initiated with only perpendicular variance. We find that parallel variance grows and saturates at about 5% of the perpendicular variance in a few nonlinear times irrespective of the Reynolds number. For sufficiently large systems (Reynolds numbers) the variance approaches values consistent with the solar wind observations.
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