Dissipation scale lengths of density turbulence in the inner solar wind

TL;DR

This study measures the dissipation lengthscales of density turbulence in the inner solar wind using radio interferometry, revealing scales from 13,500 to 520 meters and suggesting a link to proton gyroradius, aiding solar wind understanding.

Contribution

It provides the first direct estimates of turbulence dissipation scales in the inner solar wind using radio observations, connecting these scales to proton gyroradius and solar wind acceleration.

Findings

Dissipation scales range from approximately 13,500 to 520 meters.

Scales at 10-20 solar radii suggest a link to proton gyroradius.

Results are relevant for Parker Solar Probe observations.

Abstract

Knowing the lengthscales at which turbulent fluctuations dissipate is key to understanding the nature of weakly compressible magnetohydrodynamic turbulence. We use radio wavelength interferometric imaging observations which measure the extent to which distant cosmic sources observed against the inner solar wind are scatter-broadened. We interpret these observations to determine that the dissipation scales of solar wind density turbulence at heliocentric distances of 2.5 -- 20.27 $R_{\odot}$ range from $\approx$ 13500 to 520 m. Our estimates from $\approx$ 10--20 $R_{\odot}$ suggest that the dissipation scale corresponds to the proton gyroradius. They are relevant to in-situ observations to be made by the Parker Solar Probe, and are expected to enhance our understanding of solar wind acceleration.