The Radial Dependence of Proton-scale Magnetic Spectral Break During PSP Encounter 2

The proton-scale spectral break of magnetic field fluctuations is an important phenomenon in the solar wind. It is considered as the scale at which turbulent dissipation starts occurring and a transition to a kinetic turbulent cascade begins. In the cruise and encounter phases of its second orbit, Parker Solar Probe had enough resolution to continuously observe the radial dependence of the magnetic spectral break. This work reports observations of the proton-scale break near the Sun, and its evolution with solar radial distance (0.17~0.5 AU). We compare this to the plasma characteristic ion scales (proton gyroradius, proton inertial length, etc.), to relate the break to the possible mechanisms occurring at this scale. This analysis will help us to understand the origin and the development of the solar wind.