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第七讲：Particle Acceleration in Magnetic Reconnection: From Small Scale to Large Scale
Magnetic reconnection is a fundamental process leading to explosive energy release and particle acceleration. Nonthermal particle acceleration are well known as the signature features of magnetotails and solar flares. However, the multiscale nature of magnetic reconnection makes it difficult to understand particle acceleration in large-scale systems. I will present results using different tools that cover a broad range of spatial and temporal scales. I will first present fully kinetic particle-in-cell simulations of magnetic reconnection in the low plasma beta regime. We find that 3D magnetic reconnection can efficiently accelerate particles into nonthermal relativistic particles in a power-law spectrum. We have demonstrated that the dominant acceleration mechanism is a Fermi-like process due to the plasma flow and magnetic curvature (or compression/shear). To address particle acceleration by magnetic reconnection in solar flares, we have been developing a framework for studying nonthermal acceleration, transport, and radiation by combining magnetohydrodynamic simulations, particle transport, and radiation models. Our first results using this framework have shown a great potential for understanding the roles of flare configuration, magnetic reconnection and shocks in energetic electron production and distributions. Future development will include a series of realistic effects important to solar flares and gain insights by closely comparing the integrated model with multi-wavelength observations.
Fan Guo is a staff scientist at the Theoretical Division in Los Alamos National Laboratory (LANL). He received bachelor’s and master’s degrees in University of Science and Technology of China. He obtained his PhD degree in 2012 at the University of Arizona under the guidance of Professors Joe Giacalone and Randy Jokipii. He subsequently became a postdoc research associate at LANL until he became a staff member in 2016. Fan Guo’s research focuses on theoretical understanding and numerical modeling of plasma energization and particle acceleration processes in solar, space and astrophysics. He has used fully kinetic, hybrid (kinetic ions, fluid electrons), particle transport and MHD simulations to model particle acceleration in magnetic reconnection, collisionless shocks, and turbulence and built analytical theories. He has published more than 90 papers as the first author or a contributed author with more than 3000 citations. He has given more than 60 invited presentations, seminars and colloquia in various conferences and institutes. He is a member of SolFER collaboration, NASA LWS Program Analysis group committee, and APS Topical Group in Plasma Astrophysics (GPAP) committee. He is also an adjunct professor in the Department of Space Science at the University of Alabama in Huntsville.