Friday, December 15, 2017
Many space and astrophysical plasmas are so hot and diffuse that they cannot be rigorously described as fluids. These include the solar wind, low-luminosity black-hole accretion flows, and the intracluster medium of galaxy clusters. Currently, the lack of a rigorous theory for the plasma microphysics in these systems is a formidable obstacle to answering several fundamental questions in space and astrophysics. Much of the difficulty arises from the freedom in a weakly collisional plasma for the particle distribution function to be anisotropic in velocity space, as well as from the shaping of such temperature anisotropy by magnetic fields. In this talk, I will present hybrid-kinetic simulations of waves, turbulence, and magnetorotationally driven transport in collisionless, high-beta plasmas, which address how Larmor-scale kinetic instabilities are driven by and ultimately regulate temperature anisotropy, and how this regulation in turn feeds back on the macroscale dynamics. Gyrokinetic theory will also be used to explore how temperature anisotropy affects Alfvénic turbulence and ion versus electron heating in high-beta plasmas.