# smod_equil_photospheric_flux_tube Submodule

This submodule defines a magnetic flux tube embedded in a uniform magnetic environment. In this case the flux tube is under photospheric conditions $c_{Ae} < c_s < c_{se} < c_A$ where the subscript e denotes the outer region. More specifically the equilibrium is defined as $c_{Ae} = c_s/2, c_{se} = 3c_s/2, c_A = 2c_s$. The geometry can be overridden in the parfile, and is cylindrical by default for $r \in [0, 10]$.

This equilibrium is taken from chapter 6, fig. 6.5 in Roberts, Bernard (2019). MHD Waves in the Solar Atmosphere. Cambridge University Press. DOI.

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