CAREER: Particle Acceleration and Transport in the Solar Corona

University Of Alabama In Huntsville, Huntsville AL

Investigators

Abstract

Observations have established that magnetic reconnection (MR) is the principal driver of eruptive phenomena on the Sun. How MR accelerates charged particles in solar flares is a long-standing unsolved problem in solar physics. It is important to understand this process in order to predict how solar flares impact space weather near the Earth. This work will investigate particle acceleration driven by MR using a combination of theoretical modeling, numerical simulations, and spacecraft observations. The educational component involves mentoring of graduate students and postdocs, support for an existing summer school on space science and collaboration in an international graduate student exchange program. The work also supports an early career faculty member. This project is jointly funded by the Solar-Terrestrial Research, the Established Program to Stimulate Competitive Research (EPSCoR), and the Plasma Physics programs. The work is a comprehensive study aimed at substantially improving understanding of the nonlinear kinetic processes underlying particle acceleration in solar flares. This project advances the state of knowledge of particle acceleration and kinetic theory regarding (1) a novel 2nd-order Fermi-acceleration mechanism; (2) new knowledge on electron Kelvin-Helmholtz instabilities (EKHI) and kinetic turbulence including the inverse energy cascade and the expanding and merging of magnetic vortices; (3) innovative analytical treatment of particle transport in the stochastic electric field that results in the correct prediction of the electron energy spectrum in simulations given the spatial scales of turbulent fields and guide field; (4) new knowledge on ion acceleration by the resonance of EKHI and Alfven wave turbulence; (5) a new model for the “big number” problem in electron acceleration in solar flares, extending the scope from the PIC simulation scale to the size of real flares; and (6) new knowledge on particle beam development in the solar corona. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.