THE SLOW-MODE NATURE OF COMPRESSIBLE WAVE POWER IN SOLAR WIND TURBULENCE

Journal Article · Sun Jul 01 04:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/753/1/L19· OSTI ID:22047707

Howes, G G; Klein, K G; TenBarge, J M ^[1]; Bale, S D; Chen, C H. K.; Salem, C S ^[2]

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1. Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)
2. Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

We use a large, statistical set of measurements from the Wind spacecraft at 1 AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to show that the compressible component of inertial range solar wind turbulence is primarily in the kinetic slow mode. The zero-lag cross-correlation C({delta}n, {delta}B{sub ||}) between proton density fluctuations {delta}n and the field-aligned (compressible) component of the magnetic field {delta}B{sub ||} is negative and close to -1. The typical dependence of C({delta}n, {delta}B{sub ||}) on the ion plasma beta {beta}{sub i} is consistent with a spectrum of compressible wave energy that is almost entirely in the kinetic slow mode. This has important implications for both the nature of the density fluctuation spectrum and for the cascade of kinetic turbulence to short wavelengths, favoring evolution to the kinetic Alfven wave mode rather than the (fast) whistler mode.

• OSTI ID: 22047707
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 753; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
ASTROPHYSICS
CORRELATIONS
EVOLUTION
FLUCTUATIONS
IONS
MAGNETIC FIELDS
PROTON DENSITY
SOLAR CORONA
SOLAR WIND
TURBULENCE
WAVE POWER
WAVELENGTHS
WHISTLER INSTABILITY