Introduction

Magneto-rotational instability is an instability formed by the deformation of magnetic fields by centrifugal force. This instability is regardeed as the source of turbalence in the accretion disk.

[Initial Condition] A part of accretion disk is approximated in square simulation box. At far away in left hand side (x<<0) a gravitational source is assumed and the disk is nearly in Keplar rotation. Constant magnetic fields are threading the disk. In the figure, color shows density, arrows show velocity, and lines show magnetic field lines. Density is decreasing from Red, to Orange, Olive, Green, Aqua, Blue, Perple, and Black.

[Growth Stage] Because of differential rotation, inner magnetic fields move toward inward and outer magnetic fields move toward outward. As a result, magenetic field lines in the disk start rippling.