Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session BM09: Mini-Conference: Heating and Non-Thermal Particle Acceleration during Magnetic Reconnection in Laboratory, Heliophysical and Astrophysical Plasmas I
9:30 AM–12:30 PM,
Monday, October 17, 2022
Room: 206 AB
Chair: Li-jen Chen, NASA Goddard Space Flight Center; Fan Guo, Los Alamos National Laboratory
Abstract: BM09.00001 : Particle Heating and Acceleration during Magnetic Reconnection
9:30 AM–9:55 AM
Presenter:
James F Drake
(University of Maryland, College Park)
Author:
James F Drake
(University of Maryland, College Park)
hot electrons and ions and nonthermal components is a topic of broad
importance both in the heliosphere and the broader universe. I will
review observations and ideas about the mechanisms
that drive both heating and nonthermal particle production with an
emphasis on non-relativistic reconnection. An organizing parameter is
the magnetic energy released per particle $W_B=m_iV_A^2$. In regions
where $W_B$ is large such as in the Earth's magnetotail, solar flares
and the solar wind near the sun, observations reveal hot thermal
and nonthermal, powerlaw components. Single x-line models fail to
explain the generation of the nonthermal component. However,
simulations reveal that reconnection becomes turbulent in the high
$W_B$ environment. Magnetic energy release and particle acceleration
therefore take place in a multi-x-line environment. The energy gain of the most energetic particles is dominated
by Fermi reflection in growing and merging magnetic islands rather
than the parallel electric fields in kinetic scale boundary layers. On the
other hand, the large-scale parallel electric potential that develops to
maintain charge neutrality controls the heating of the
hot thermal electrons during reconnection. The
kinetic scale boundary layers that control the parallel electric field
are not important in energy release in large-scale
systems. Particle-in-cell simulations are revealing powerlaw
distributions of both electrons and protons. However, the PIC models
fail to produce the extended powerlaws seen in some observations
because of inadequate separation of kinetic and macroscales. A new
computational model, {\it kglobal}, has been developed that blends MHD
dynamics with electron and ion particles but eliminates all kinetic
scales. Simulations of reconnection in a macro-scale system reveal
powerlaw distributions that extend nearly three decades in energy and
that the dominant control parameter is the ambient guide magnetic
field.
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