  We present new 3D magnetohydrodynamic (MHD) simulations of a
supernova-driven, stratified interstellar medium. These simulations were run
using the Waagan (2009) positivity preserving scheme for ideal MHD implemented
in the Flash code. The scheme is stable even for the Mach numbers approaching
100 found in this problem. We have previously shown that the density
distribution arising from hydrodynamical versions of these simulations creates
low-density pathways through which Lyman continuum photons can travel to
heights |z| > 1 kpc. This naturally produces the warm ionized medium through
photoionization due primarily to O stars near the plane. However, our earlier
models reproduce the peak but not the width of the observed emission measure
distribution. Here, we examine whether inclusion of magnetic fields and a
greater vertical extent to the simulation domain produce a gas distribution
that better matches the observations. We further study the change of magnetic
energy over time in our models, showing that it appears to reach a steady state
after a few hundred megayears, presumably supported by a turbulent dynamo
driven by the supernova explosions.
