# smod_equil_MRI Submodule

This submodule defines magneto-rotational instabilities in an accretion disk. Due to the special nature of this equilibrium x_start is hardcoded to one and can not be overridden in the parfile, the same goes for the geometry which is hardcoded to 'cylindrical'. The outer edge can be chosen freely. This equilibrium is chosen in such a way that the angular rotation is of order unity, implying Keplerian rotation. The thin-disk approximation is valid with small magnetic fields, but still large enough to yield magneto-rotational instabilities. Gravity is assumed to go like $g \thicksim 1/r^2$.

This equilibrium is taken from section V in Goedbloed, J. P. "The Spectral Web of stationary plasma equilibria. II. Internal modes." Physics of Plasmas 25.3 (2018): 032110. and also appears in section 13.5, fig. 13.7 in Goedbloed, H., Keppens, R., & Poedts, S. (2019). Magnetohydrodynamics of Laboratory and Astrophysical Plasmas. Cambridge University Press. DOI.

## Module Procedures

### module procedure MRI_accretion_eqmodule module subroutine MRI_accretion_eq(settings)

#### Arguments

TypeIntentOptionalAttributesName
type(settings_t), intent(inout) :: settings