Cuts of the eVDFs along the parallel (top) and perpendicular (bottom) directions at 0.3 au (left) and 1 au (right). Blue curve: observation from Helios 2 at 0.3 au (D. Verscharen et al. 2019)). Cyan curves: observations from Wind at 1 au (C. S. Salem et al. 2023). Red curves: results from the coupled model with turbulence-derived diffusion coefficients (new). Black curves: results from the power-law-based model (old). Green dashed curves: fitted Maxwellian distributions.