Collisional heating rate Q versus distance from the (loop-top) acceleration region. The solid line shows the results for collisional scattering, with the dashed line showing the behavior in the nondiffusive approach. The other lines show the results for turbulent scattering, with a turbulent scattering length λ_T equal to 0.1× (red), 0.2× (green), and 0.3× (blue) the collisional mean free path of 7 × 10⁷ cm.