Turbulence in Collisionless Astrophysical Plasmas

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Astrophysical plasmas are rarely observed to be static. Instead theyvary strongly in both time and space, a phenomena known as turbulence.Such plasmas are also typically endowed with magnetic fields, justlike the Earth and the Sun. An understanding of turbulence inmagnetized plasmas (known as MHD turbulence) is thus required tounderstand a wide variety of astrophysical phenomena, from the solarwind in our solar system (and how the solar wind impacts Earth) torotating disks of gas falling into black holes (which produce some ofthe brightest sources of light in the Universe). Our proposedresearch is aimed at understanding the behavior of MHD turbulence onsmall scales where the energy is converted into heat.We propose to carry out large-scale numerical calculations of theproperties of MHD turbulence on small scales. These calculations willpredict observable properties of the turbulence that can be directlycompared to measurements in the solar wind, and ultimately tomeasurements in the laboratory on Earth. The same calculations willpredict how plasmas are heated when the energy contained in theturbulence is dissipated -- one of the major unsolved problems in ourunderstanding of turbulence. These results will be compared tomeasurements in the solar wind; they will also be used to predict thelight we see from plasma falling into black holes -- our primaryobservational window onto black holes in nature. More broadly, thecalculations proposed here will advance the state-of-the-art innumerical modeling of turbulence in magnetized plasmas and will haveimplications for a wide variety of laboratory, space, andastrophysical plasmas.