Michael Hesse (Uni Bergen)

Magnetic reconnection and its role as a particle accelerator
When Dec 05, 2019 from 02:30 PM to 03:30 PM
What
  • Colloquium
Where SH Lecture Hall
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Magnetic reconnection in plasmas is an efficient mechanism to convert stored magnetic energy to particle energy in an often-explosive fashion. It has hence been the subject of scientific interest for many years, but, until recently, its inner workings have been inaccessible to measurements. The combination of NASA’s MMS mission and modern theory and modeling has now shed light on the inner workings of the reconnection diffusion region. Magnetic reconnection is also a particle accelerator. Particle energization can be in form of increases of thermal energy, the kinetic energy inherent in bulk plasma motion, and in form of energetic tails of particle distribution functions. Acceleration can further occur by means of direct acceleration by the reconnection electric field or by Hall-type electric fields in the current layer, by the thermalization of particle beams, and by Fermi-type acceleration in the reconnection outflow region. Finally, there is excellent theoretical and observational evidence of the generation of high-energy tails not directly associated with the reconnection process, but rather as a result of magnetic reconfigurations downstream of the reconnection outflow. This talk with consist of an overview of the magnetic reconnection process, and of the various modes of particle acceleration associated with it. Theoretical predictions will be supported by observations, in particular from spacecraft operating in the near-Earth plasma environment.