Space Physics Seminar spring-2013

Heliophysics is presently entering an exciting new era, with a fleet of missions this decade---including the Van Allen Probes, Interface Region Imaging Spectrograph (IRIS), Magnetospheric Multiscale (MMS), Solar Orbiter, and Solar Probe Plus missions---set to drive breakthroughs in our understanding of the flow of energy from the sun, through interplanetary space, to the magnetospheres of the Earth and other planets, and to the outer boundary of the heliosphere. Some of the outstanding problems in heliophysics we hope to solve include the heating of the solar corona and acceleration of the solar wind, the storage and explosive release of magnetic energy in the solar atmosphere and the propagation of these disturbances through the heliosphere, the energization and loss of energetic particles trapped in the Earth's magnetosphere, and the effects of the variable solar wind forcing on the coupled system of Earth's magnetosphere, ionosphere, and thermosphere. Key to progress in our understanding of these numerous science challenges is the discovery and characterization of the fundamental processes that govern the evolution of the heliospheric plasma, in particular the three grand challenge problems of plasma turbulence, magnetic reconnection, and energetic particle acceleration. The volume and quality of spacecraft measurements have transformed heliophysics into a deeply quantitative field, and the investigation of the underlying kinetic plasma physics of the heliospheric plasma is essential to exploit this data to the fullest degree and to progress in solving these grand challenge problems. In this talk, I will highlight recent successes in the effort to develop a comprehensive understanding of turbulence in kinetic plasmas, a research program involving a broad but coordinated approach of theoretical modeling, massively parallel gyrokinetic numerical simulations, novel analyses of spacecraft measurements, and laboratory experiments. The detailed investigation of the kinetic plasma physics of turbulence and its dissipation has driven the cutting edge of this research program to the realm of electron-scale current sheets and magnetic reconnection. Ultimately, the ubiquity of plasma turbulence in the heliosphere suggests that a mature understanding of the nature of kinetic plasma turbulence will be critical to fully explaining the explosive release of magnetic energy in reconnection and the acceleration of energetic particles in heliospheric plasmas.