II. Transport of Nearly Incompressible Magnetohydrodynamic Turbulence from 1 to 75 au

Journal Article · Thu Jun 01 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA6F5D· OSTI ID:22872674

Adhikari, L.; Zank, G. P.; Hunana, P.; Hu, Q. ^[1]; Shiota, D. ^[2]; Bruno, R. ^[3]; Telloni, D. ^[4]

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1. Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)
2. Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601 (Japan)
3. INAF-IAPS Instituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy)
4. INAF—Astrophysical Observatory of Torino, Via Osservatorio 20, I-10025 Pino Torinese (Italy)

The thermal plasma beta in the solar wind and the solar corona is of the order of β∼1 and β≪1. Zank et al. developed 2D and slab turbulence transport model equations of the order of β∼1 and β≪1 using nearly incompressible (NI) theory. We solve the Zank et al. NI MHD coupled turbulence transport equations for the inhomogeneous solar wind from 1 to 75 au, and compare the numerical solutions to Voyager 2 observations. We find that (1) the 2D turbulent energies are larger than the slab energies throughout the heliosphere; (2) the 2D turbulent energies decrease more slowly than the slab turbulent energies within ∼4 au, while the slab energies increase and the 2D energies flatten in the outer heliosphere; (3) the 2D normalized cross-helicity decreases faster than the slab normalized cross-helicity within ∼4 au; (4) the 2D normalized residual energy is more magnetically dominated than the slab; (5) the variance of density fluctuations decreases more rapidly than r{sup −4} within ∼10 au, and more slowly in the outer heliosphere; and (6) the observed variance in magnetic field fluctuations as a function of the thermal plasma beta is described by the two-component turbulence transport model. In summary, the NI MHD two-component Zank et al. turbulence transport model captures the behavior of the forward, backward, and total energies in the fluctuating Elsässer variables, the variance in the magnetic field, kinetic energy, and density fluctuations, the cross-helicities and residual energies, the thermal temperature and plasma beta, and the various correlation lengths.

• OSTI ID: 22872674
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 841; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
FLUCTUATIONS
HELIOSPHERE
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NUMERICAL SOLUTION
PLASMA
SOLAR CORONA
SOLAR WIND
TRANSPORT THEORY
TURBULENCE