The CH+ Abundance in Turbulent, Diffuse Molecular Clouds
  The intermittent dissipation of interstellar turbulence is an important
energy source in the diffuse ISM. Though on average smaller than the heating
rates due to cosmic rays and the photoelectric effect on dust grains, the
turbulent cascade can channel large amounts of energy into a relatively small
fraction of the gas that consequently undergoes significant heating and
chemical enrichment. In particular, this mechanism has been proposed as a
solution to the long-standing problem of the high abundance of CH+ along
diffuse molecular sight lines, which steady-state, low temperature models
under-produce by over an order of magnitude. While much work has been done on
the structure and chemistry of these small-scale dissipation zones,
comparatively little attention has been paid to relating these zones to the
properties of the large-scale turbulence. In this paper, we attempt to bridge
this gap by estimating the temperature and CH+ column density along diffuse
molecular sight-lines by post-processing 3-dimensional MHD turbulence
simulations. Assuming reasonable values for the cloud density (30 / cm^3), size
(20 pc), and velocity dispersion (2.3 km / s), we find that our computed
abundances compare well with CH+ column density observations, as well as with
observations of emission lines from rotationally excited H2 molecules.
