Physics & Astronomy/Thayer Plasma Seminar - Xiaocan Li, Los Alamos National Lab

Dartmouth Events

Physics & Astronomy/Thayer Plasma Seminar - Xiaocan Li, Los Alamos National Lab

Title: "Particle Acceleration During Magnetic Reconnection in Solar Flares"

Tuesday, October 23, 2018
3:30pm-4:30pm
Wilder 202
Intended Audience(s): Public
Categories: Lectures & Seminars
Abstract: Magnetic reconnection is a major mechanism that drives the release of magnetic energy and accelerates particles in space and astrophysical plasmas. Solar flares are a great example where observations have suggested that a large fraction of magnetic energy is converted into nonthermal particles and radiation. Such efficient particle acceleration over a large-scale reconnection region is an important problem that remains unsolved. Studies have shown that reconnection in solar flares can naturally develop structures at different scales. We, therefore, adopt a multi-scale approach to study the acceleration of particles during magnetic reconnection in solar flares. First I present results from both 2D and 3D kinetic simulations, where we study the formation of power-law energy distributions and particle acceleration mechanisms. We show that 3D effects and the Fermi-like process due to particle curvature drift are essential for power-law formation in non-relativistic reconnection. For a sufficiently large system, the Fermi-like process is included in flow compression and shear, which are often studied in energetic particle transport theories. We then proceed to solve Parker's transport equation in a compressible reconnection flow provided by high-Lundquist-number MHD simulations. Due to the compression effect, particles are accelerated to high energies and develop power-law energy distributions. The power-law index and maximum energy are both comparable to solar flare observations. This study clarifies the nature of particle acceleration in large-scale reconnection sites and initializes a framework for studying particle acceleration during solar flares.
 
For more information, contact:
Tressena Manning
603-646-2854

Events are free and open to the public unless otherwise noted.