Carlos Gonzalez, UT Austin

"Local proton heating at magnetic discontinuities in the Alfv ́enic and non-Alfv ́enic solar wind"

Abstract: Understanding how the solar wind is heated while it expands in the inner heliosphere remains an open fundamental question. Plasma temperature enhancements have been commonly associated with intermittent structures or magnetic discontinuities. However, solar wind streams differ by the type of fluctuations and turbulence, and which mechanism that lead to proton heating are favored in different solar wind conditions remains to be understood. Here we investigate local proton energization at magnetic structures/discontinuities and the corresponding kinetic signatures in velocity phase space in Alfv ́enic (high cross helicity) and non-Alfv ́enic (low cross helicity) wind, by us- ing Parker Solar Probe observations at distances 0.07 < R < 0.263 AU. We complement our data analysis with 2.5 hybrid-kinetic simulations to understand what processes are likely to contribute to the observed proton heating and temperature anisotropy in the two types of wind. We compare the local kinetic features and temperature enhancements found in Alfv ́enic and non-Alfv ́enic streams and discuss to what extent they can be explained in terms of wave-like vs 2D turbulence dynamics.