2018/01/31 by Lloyd D. Woodham, L. D. Woodham, Robert T. Wicks +4 · 1 citation
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Atomic physics #Computational physics #Geomagnetism and Paleomagnetism Studies #Helicity #Ionosphere and magnetosphere dynamics #Magnetic field #Mechanics #Nuclear physics #Physics #Proton #Quantum mechanics #Solar and Space Plasma Dynamics #Solar wind #Turbulence #physics.plasm-ph #physics.space-ph
paper · pdf · doi:10.3847/1538-4357/aab03d
published as ApJ, 856 (2018), 49 · 16 pages, 11 figures. Accepted for publication in The Astrophysical Journal. Please contact authors to obtain WIND MFI 'noise-floor' for use in other studies
arxiv created 2018/02/14 · openalex publication_date 2018/03/20 · arxiv updated 2018/03/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract We use magnetic field and ion moment data from the MFI and SWE instruments on board the Wind spacecraft to study the nature of solar wind turbulence at ion-kinetic scales. We analyze the spectral properties of magnetic field fluctuations between 0.1 and 5.4 Hz during 2012 using an automated routine, computing high-resolution 92 s power and magnetic helicity spectra. To ensure the spectral features are physical, we make the first in-flight measurement of the MFI “noise-floor” using tail-lobe crossings of the Earth’s magnetosphere during early 2004. We utilize Taylor’s hypothesis to Doppler-shift into the spacecraft frequency frame, finding that the spectral break observed at these frequencies is best associated with the proton cyclotron resonance scale, 1/ k c , rather than the proton inertial length, d i , or proton gyroscale, ρ i . This agreement is strongest when we consider periods where , and is consistent with a spectral break at d i for and at ρ i for . We also find that the coherent magnetic helicity signature observed at these frequencies is bounded at low frequencies by 1/ k c , and its absolute value reaches a maximum at ρ i . These results hold in both slow and fast wind streams, but with a better correlation in the more Alfvénic fast wind where the helicity signature is strongest. We conclude that these findings are consistent with proton cyclotron resonance as an important mechanism for dissipation of turbulent energy in the solar wind, occurring at least half the time in our selected interval. However, we do not rule out additional mechanisms.