Statistical Analysis of Intermittency and its Association with Proton Heating in the Near-Sun Environment

We use data from the first six encounters of the Parker Solar Probe and employ the partial variance of increments (PVI) method to study the statistical properties of coherent structures in the inner heliosphere with the aim of exploring physical connections between magnetic field intermittency and observable consequences such as plasma heating and turbulence dissipation. Our results support proton heating localized in the vicinity of, and strongly correlated with, magnetic structures characterized by PVI >= 1. We show that, on average, such events constitute approximate to 19% of the data set, though variations may occur depending on the plasma parameters. We show that the waiting time distribution (WT) of identified events is consistent across all six encounters following a power-law scaling at lower WTs. This result indicates that coherent structures are not evenly distributed in the solar wind but rather tend to be tightly correlated and form clusters. We observe that the strongest magnetic discontinuities, PVI >= 6, usually associated with reconnection exhausts, are sites where magnetic energy is locally dissipated in proton heating and are associated with the most abrupt changes in proton temperature. However, due to the scarcity of such events, their relative contribution to energy dissipation is minor. Taking clustering effects into consideration, we show that smaller scale, more frequent structures with PVI between 1 less than or similar to PVI less than or similar to 6 play a major role in magnetic energy dissipation. The number density of such events is strongly associated with the global solar wind temperature, with denser intervals being associated with higher T ( p ).

Automated summary

This study uses data from the Parker Solar Probe to investigate the statistical properties of coherent structures in the inner heliosphere. The results show a correlation between magnetic field intermittency and observable consequences such as plasma heating and turbulence dissipation. Proton heating is found to occur in magnetic structures characterized by a partial variance of increments (PVI) value of 1 or higher. The study also reveals that coherent structures are not evenly distributed and tend to form clusters. Smaller scale structures with a PVI value between 1 and 6 play a major role in magnetic energy dissipation.