On the Saturation Mechanism of MHD Turbulence in Accretion Disks: 
MRI vs. Magnetic Reconnection
  
T. Sano (Osaka Univ.)

We investigate the nonlinear evolutions of the magnetorotational
instability (MRI) in accretion disks using three-dimensional MHD
simulations.  The saturation level of the MRI is determined by a
balance between the growth of the MRI and the dissipation of the field
through reconnection.  Thus the magnetic reconnection is essential to
understand the saturation mechanism of the turbulence.  In this paper,
we focus on the breakup phase of the magnetorotationally unstable
modes, so called channel-flow modes, and examine the triggering
mechanism of reconnection and the dissipation rate of the field.  The
dependence of the results on physical quantities, such as the gas
pressure and the magnetic diffusivity, is also discussed.