Collaborative Research: Particle-in-Cell Simulations of the Global Stability and Relaxation of Kinetic-Scale Structures in a Collisionless Magnetized Plasma

This award supports a collaboration between the University of Alaska, Fairbanks and the University of New Hampshire to study structure formation in collisionless plasmas. Most observable matter in the universe, including the Sun and other stars, exists in the plasma state. Many of these plasmas, such as the solar wind, are referred to as 'collisionless' because the constituent charged plasma particles very rarely interact directly. A collisionless plasma can form substructures that are sometimes stable and sometimes not, on scales much larger than the size of individual plasma particles but much smaller than the scale of the plasma itself. The study of how these structures evolve will contribute to our understanding of many space and laboratory plasma phenomena such as magnetic reconnection, may improve our ability to predict space weather, and may advance the development of nuclear fusion as a viable energy source. This project will support the training of graduate students at both institutions and will contribute to local education and outreach activities. The main objective of this project is to theoretically and computationally study the global stability and nonlinear relaxation of localized small-scale kinetic structures that are fundamental to the basic properties of collisionless magnetized plasmas. The global stability and nonlinear relaxation of analytic Vlasov-Poisson-Ampère equilibria will be studied, as well as the dynamical evolution of more generic initial conditions, to understand how common these small-scale structures are in realistic plasmas, to determine if a global unstable mode grows much slower than predicted by a local theory, and if an instability saturates to a stable nonlinear equilibrium. New insights in kinetic physics obtained through this project will have fundamental impacts on basic plasma theory, as well as contribute to understanding frontier problems in laboratory, space and astrophysical plasmas including magnetic reconnection, space weather, and the formation of spiral arms in disk galaxies. 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.