This paper employs a recent turbulent heating prescription to predict the ratio of proton-to-total heating due to the kinetic dissipation of Alfvénic turbulence as a function of heliocentric distance .
Comparing to a recent empirical estimate for this turbulent heating ratio in the high-speed solar wind , the prediction shows good agreement with the empirical estimate for R \gtrsim 0.8 AU , but predicts less ion heating than the empirical estimate at smaller heliocentric radii .
At these smaller radii , the turbulent heating prescription , calculated in the gyrokinetic limit , fails because the turbulent cascade is predicted to reach the proton cyclotron frequency before Landau damping terminates the cascade .
These findings suggest that the turbulent cascade can reach the proton cyclotron frequency at R \lesssim 0.8 AU , leading to a higher level of proton heating than predicted by the turbulent heating prescription in the gyrokinetic limit .
At larger heliocentric radii , R \gtrsim 0.8 AU , this turbulent heating prescription contains all of the necessary physical mechanisms needed to reproduce the empirically estimated proton-to-total heating ratio .