Year: 2026
Type: article
Abstract: Magnetic helicity is typically indistinguishable from noise in the solar wind inertial range. Using Parker Solar Probe measurements (0.1–0.8 au), we report a robust bihelical structure emerging at the magnetohydrodynamic (MHD)–kinetic interface. This structure, formed by a striking pair of positive and negative peaks, exhibits a systematic spectral migration toward lower frequencies with increasing heliocentric distance. Crucially, this evolution deviates from local kinetic scaling laws, such as the radial decline of the ion cyclotron frequency, reflecting a nonlocal evolution of magnetic topology. Our findings provide a new observational constraint on both nonlocal MHD transport processes and the nature of the helicity barrier in the kinetic regime.
Institutions: Technische Universität Braunschweig, Max Planck Institute for Solar System Research, Istituto Nazionale di Geofisica e Vulcanologia, University of California System, Stockholm University, Ilia State University, Carnegie Mellon University, KTH Royal Institute of Technology, Adelaide University, The University of Adelaide, Instituto Nacional de Pesquisas Espaciais, Institute of Space Science - INFLPR Subsidiary, Kyushu University, The University of Osaka, Tohoku University, Université de Lyon, The University of Tokyo
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
OpenAlex ID: W4415310451