Authors: B. Chandran (U. New Hampshire), S. Bale (UC Berkeley), J. Halekas (U. Iowa), K. Klein (U. Arizona), J. Squire (U. Otago)

Alfvenic turbulence plays a dominant role in energizing coronal holes and a large fraction of the near-Sun solar wind. In these regions, the dominant component of the turbulence is Alfven waves (AWs) that propagate away from the Sun in the plasma frame. This type of ‘imbalanced turbulence’ (in which outward-propagating AWs are much more energetic than inward-propagating AWs) is subject to the recently discovered helicity barrier, which allows only balanced (i.e., equal) fluxes of inward and outward wave energy to cascade to smaller scales at scales smaller than the proton gyroradius. As a consequence, the total turbulent heating rate is limited to the rate at which fluctuations dissipate at scales comparable to or larger than the proton gyroradius, plus twice the cascade power of the relatively weak inward-propagating AWs. In this poster, we present results from a two-fluid flux-tube solar-wind model with temperature anisotropy and reflection-driven AW turbulence. We determine the turbulent heating rate using a phenomenological model that incorporates the helicity barrier, and we compare our results with data from the Parker Solar Probe.