This project will enable better understanding of the generation of cosmic rays throughout the Universe. The Universe is permeated with plasma, an ionized gas where magnetic fields and charged particles evolve under their mutual interaction. A small fraction of the charged particles may be accelerated to very large energies and, despite being less than one percent in number, affect the overall plasma in a prominent way. The project aims to study via controlled, self-consistent numerical plasma simulations the processes through which such energetic particles generate and are impacted by magnetic fields in the solar system and other astrophysical environments. The project will train graduate and undergraduate students, with particular emphasis on attracting underrepresented minorities into the field, while the new knowledge is likely to improve our ability to predict space weather and may impact design of future fusion reactors.
Non-thermal particles can be produced via several different physical phenomena such as shocks, magnetic reconnection, and turbulence, tapping into the free energy of the system, be it kinetic or magnetic. The streaming of solar energetic particles in the heliosphere and cosmic rays in astrophysical contexts naturally produces a restoring back-reaction in the thermal plasma, which leads to tangling/amplification of the initial magnetic field. Kinetic particle-in-cell simulations will be used to quantify ab-initio the self-generated scattering of the energetic particles and how energy is partitioned into electromagnetic fields, plasma heating, and bulk motions. Instabilities driven by energetic ions and electrons are key to the phenomenology of diverse space/astrophysical environments, such as collisionless shocks, the solar wind, and pulsar wind nebulae.
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.