Energy Transfer in Collisionless Astrophysical Plasmas

University Of Rochester, Rochester NY

Investigators

Abstract

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This research focuses on two frontiers of plasma physics where particle-in-cell (PIC) simulations can help elucidate underlying principles of energy transfer in plasmas: (1) Motivated by collisionless accretion disks, we will study whether a faster-than-Coulomb energy transfer between ions and electrons can occur in a two-temperature plasma with an anisotropic ion temperature much higher than the electron temperature. Electron-proton coupling via waves generated by bulk sheared flows, Weibel, two-stream, and other collisionless MHD instabilities will be considered. The presence or absence of a faster-than-Columb coupling will place rigorous constraints on the viability of two-temperature accretion flows such as advection dominated accretion flows as a paradigm for the radiatively inefficient accretion flows of some galactic nuclei, and states of X-ray binaries. (2) Motivated by the fundamental role of the current-driven Weibel-type instabilities in both astrophysically motivated shocks and laser-driven shocks, researchers will study and compare the formation and magnetic field generation in both types. Undergraduates will be involved in the data analysis and visualization. Support for an ongoing undergraduate radio show at the University of Rochester will be expanded. The show highlights a few science and engineering developments biweekly for a short, but repeated 3-4 minute broadcasts to the Rochester area. A course on PIC simulations is being developed at UR for graduate and undergraduate students from physics, astrophysics, and engineering. Lectures on PIC will also be given at the Summer Schools organized by the UR DOE Fusion Science Center. This project will generate new teaching materials to demonstrate how PIC simulations can be applied to new research areas. The project will also train graduate students and postdoctoral researchers with interdisciplinary expertise in plasma physics, astrophysics, and PIC simulations. This proposal was submitted to the NSF-DoE Partnership in Plasma Science and Engineering joint solicitation 08-589. This award is being funded jointly by the Divisions of Physics and Astronomical Sciences of the Mathematical and Physical Sciences Directorate.