Comparison of Solar Wind Current Sheets in the Inner Heliosphere

Abstract The solar wind is filled with intense current sheets (magnetic field discontinuities) that host multiple instabilities and may undergo magnetic reconnection, a basic process for plasma heating and charged particle acceleration. Although numerous studies have examined current sheets, most statistical analyses cover relatively narrow heliocentric ranges, leaving essential aspects of their radial dependence only partially resolved. In order to investigate how current sheet properties evolve as the solar wind expands, we analyze three intervals when the Parker Solar Probe (PSP) was near perihelion and compare its observations with near-Earth measurements from ARTEMIS and WIND. We identify and characterize more than 45,000 current sheets across the three intervals, including approximately 17,000 from PSP. We find that current sheets broaden with increasing heliocentric distance, while their characteristic current density decreases proportionally to their Alfvén current density ( J A = eNV A , where symbols have their usual definitions). Most current sheets exhibit only small variations in magnetic field magnitude. Their thickness and current density are strongly anti-correlated, indicating that thinner current sheets carry stronger currents, consistent with intermittent turbulence. Distinct distributions of magnetic field jumps and rotation angles across different missions suggest structural evolution as the solar wind expands. We also quantify their departure from the Walén relation, which describes the expected correspondence between velocity and magnetic-field jumps for an ideal rotational discontinuity. Significant deviations persist even after accounting for plasma pressure anisotropy. Finally, the Alfvénicity of the current sheets correlates strongly with the cross helicity and residual energy of the surrounding solar wind.