  Arecibo spectra of the mainline OH maser emission from U Her over more than a
decade show variations of the OH emission over these time scales. These
observations are combined with high spatial resolution VLBA maps to investigate
the causes of the variations in the velocities of the maser components. Global
properties of the dust shell, such as accelerations, variations in the pump and
shell-wide magnetic field changes are examined as possibilities, and
eliminated. A possible solution to the problem involving plasma turbulence and
the local magnetic field is introduced, and the relevant time scales of the
turbulence are calculated. The turbulent velocity field yields time scales of
the turbulence are calculated. The turbulent velocity field yields time scales
that are too long (of order centuries), while the turbulent magnetic field
produces variations on appropriate time scales of a few years. A line-of-sight
model of the turbulence is developed and investigated. The complete exploration
of this solution requires extensive theoretical and observational work.
Possible avenues of investigation of the plasma turbulence model are presented.
