Probing Proton versus Electron Heating and Energization during Magnetic Reconnection

Abstract

The mechanisms controlling the relative heating and energization of electrons and protons during magnetic reconnection are explored. Simulations are carried out with the kglobal model, which produces bulk heating and the extended powerlaw distributions of both species that have been documented in observations. The simulations have been carried out with a range of proton-to-electron mass ratios and upstream temperatures to isolate the factors that control energy gain. The simulations reveal that when the upstream temperatures of the two species are equal, the proton heating and energization exceeds that of electrons and that this is a consequence of the much larger energy gain of protons on their first entry into the reconnection exhaust. The effective energy gain of protons on exhaust entry scales as $m_i{C}_A^2$ since the protons counterstream at the Alfvén speed $C_A$ while the initial electron energy gain is smaller by the factor $({\beta }_{e0}{m}_e/m_i{)}^{1/2}$. Since Fermi reflection during flux rope merger dominates energy gain in large-scale reconnecting systems and the rate of energy gain is proportional to energy, protons continue to gain energy faster than electrons for the duration of the simulations, leading to temperature increments of protons exceeding that of electrons and the non-thermal energy content of protons also exceeding that of electrons.

13 pages, 7 figures

References in corpus (21)

• Instability of current sheets and formation of plasmoid chains
• Fast Reconnection in High-Lundquist-Number Plasmas Due to Secondary Tearing Instabilities
• Global Energetics of Thirty-Eight Large Solar Eruptive Events
• Formation of Hard Power-laws in the Energetic Particle Spectra Resulting from Relativistic Magnetic Reconnection
• Electron-Scale Dynamics of the Diffusion Region during Symmetric Magnetic Reconnection in Space
• Two-scale structure of the electron dissipation region during collisionless magnetic reconnection
• Electron Acceleration by Multi-Island Coalescence
• The Mechanisms of Electron Heating and Acceleration during Magnetic Reconnection
• Microwave and Hard X-Ray Observations of the 2017 September 10 Solar Limb Flare
• The power-law spectra of energetic particles during multi-island magnetic reconnection
• Electron Acceleration during Macroscale Magnetic Reconnection
• Reduction of Ion Heating During Magnetic Reconnection by Large-Scale Effective Potentials
• A Statistical Model of Magnetic Islands in a Large Current Layer
• Electron Heating During Magnetic Reconnection: A Simulation Scaling Study
• Formation of Power-law Electron Energy Spectra in Three-dimensional Low-$\beta$ Magnetic Reconnection
• A computational model for exploring particle acceleration during reconnection in macro-scale systems
• Large-Scale Parallel Electric Fields and Return Currents in a Global Simulation Model
• Simultaneous Proton and Electron Energization during Macroscale Magnetic Reconnection
• A Computational Model for Ion and Electron Energization during Macroscale Magnetic Reconnection
• Magnetic reconnection-driven energization of protons up to 400 keV at the near-Sun heliospheric current sheet
• Energy partitioning between thermal and non-thermal electrons and ions in magnetotail reconnection