Constraints on the heating and acceleration of Alfvénic streams using Parker Solar Probe data and a two-temperature solar wind model

During its encounter, Parker Solar Probe can sample the plasma outflow from the Sun in periods of corotation, allowing us to follow the solar wind during its radial evolution. We analyze plasma and magnetic field properties in two periods of corotation when Alfvènic streams of the solar wind were sampled. These data are then compared with results of a solar wind model.

In particular, the numerical model is an updated version of VPE (Grappin et al. 2011 ApJ) that solves one one-dimensional MHD equations including radiation and conduction, with separate proton and electron temperatures. Integration starts from the chromosphere and reaches PSP orbit and beyond.  Magnetic and velocity fluctuations are also injected from the chromosphere and  can contribute to the heating of the solar wind via a phenomenological turbulent dissipation (VPEW model). 

We use measurements to constrain several free parameters of the model, namely the chromospheric density, the magnetic field intensity and expansion, the fluctuations amplitude, and the turbulent phenomenology, and discuss their implications for the plasma properties closer to the Sun and for the heating and acceleration of the solar wind.