Justin Walker, University of Wisconsin-Madison

"MHD turbulence driven by the magnetorotational instability"

Abstract: The magnetorotational instability is considered to play an important role in natural systems such as astrophysical accretion disks. In the presence of a weak magnetic field, a differentially rotating and electrically conducting fluid can be unstable. Plasmas in disks are driven to a turbulent state that is thought to be responsible for angular momentum transport in the disk. Understanding this local turbulence driven is an important component of describing the larger system.

Shearing-box simulations with a weak imposed field (net flux) indicate that the resulting flow exhibits features of strong, driven MHD turbulence. Setups with no imposed field (zero net flux) demonstrate that the presence of self-sustained turbulence - driven by a dynamo - is dependent on the effectiveness of large-scale turbulent mixing.