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Session: Heliophysics and the Solar System

Name: Mr. Nikolaos Sioulas (UCLA)
Coauthors: No coauthors were included.
Type: Poster
Title: Magnetic field spectral evolution in the inner heliosphere
Abstract:

Leveraging data from the Parker Solar Probe and Solar Orbiter missions, we examine the radial evolution and underlying plasma parameter dependence of power and spectral index anisotropy in the wave vector space of solar wind turbulence, spanning heliocentric distances 0.06 ≤ R ≤ 220 Rs. Our observations reveal that near the Sun, the inertial range is constrained to a narrow range of scales, displaying a power-law exponent of αΒ = -3/2, independent of plasma parameters. Turbulence spectra associated with large magnetic energy excesses and low Alfvénic contents steepen considerably with distance, unlike highly Alfvénic intervals that preserve their near-Sun scaling. As the distance increases, the inertial range extends to larger spatial scales, progressively steepening, on average, towards an αB = -5/3 scaling. Our study also uncovers distinct radial evolutions of anisotropic turbulence signatures in fast (Vsw ≥ 400 km/s) and slow (Vsw ≤ 400 km/s) wind streams. Slow wind streams at Earth's orbit exhibit a "critically balanced" cascade, with anisotropy decreasing with diminishing heliocentric distance. In contrast, fast streams retain their near-Sun anisotropic properties, more closely reflecting a "dynamically aligned" cascade.