Ion Acceleration in an HCS Reconnection Event

by Zhiyu Yin

March 29, 2024 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility;

Advisor: Professor James Drake and  Dr. Marc Swisdak

In E14 the Parker Solar Probe (PSP) encountered a reconnection event in the heliospheric current sheet (HCS) that revealed strong ion energization with power law distributions of protons extending to 500keV.  Because the energetic particles were streaming sunward from an x-line that was anti-sunward of PSP, the reconnection source of the energetic ions was unambiguous.  The physics of particle energization in this event has been explored with the kglobal simulation model, which is now able to study electron and ion power law formation during reconnection in macro-systems.  Using upstream parameters based on the data observed by PSP, we simulate the dynamics of reconnection and analyze the resulting spectra of energetic electrons and protons.  The current layer forms multiple x-lines and associated magnetic islands that undergo merger to drive particle energization through the Fermi reflection.  Power law distributions extending nearly three decades in energy develop with proton energies extending to 500keV, consistent with observations.  Protons gain more energy than electrons.  We discuss the significance of these results for particle energization in the HCS and more generally for reconnection driven energy release throughout the heliosphere.

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