The extragalactic radio source NGC6334B
is the most strongly scattered object known, with an angular size
of 3" at 20 cm wavelength.
Its angular size
scales as the square of the observing wavelength,
and its phase structure function has a power-law dependence
on projected baseline length.
These properties suggest that NGC6334B
is a point source, probably a quasar,
scatter-broadened by an intervening
region of turbulent plasma. The line
of sight to the source intercepts the northern lobe of the bipolar
HII region NGC6334A, which is probably the source of the scattering.
We discuss observations of NGC~6334B with
the VLA at 1.4, 2, 6, 20 and 90 cm,
and with the VLBA at 1.4, 3.6 and 6 cm.
The VLA observations indicate that
the scattering disk of NGC6334B is anisotropic, with an axial
ratio of ~1.2 at 20 and 6 cm, and ~1.5 at 2 cm.
This anisotropy is probably due to the effects of a magnetic field in the
scattering medium. The position angle of the scattering disk
implies that the mean projected magnetic field direction is parallel
to the outflow from NGC6334A.The position angle of the scattering disk
rotates slightly between 6 and 2 cm; we use this rotation to place
an upper limit on the outer scale of turbulence of 10^16 cm.
We present a new algorithm to detect the presence of weak
fringes in interferometric data.
Detections of low-level excess visibility on long VLBA baselines
at 3.6 cm place an upper limit on the inner dissipative
scale of turbulence of 10^(11-12) cm, while the
baseline scaling of fringe visibility amplitude and the
wavelength scaling of scattering disk size
place a lower limit on the inner scale of 5x10^6 cm.
Nearby high velocity
(-80 km/s) water maser features show little sign of
broadening, implying that they are in front of, or less
than 100 pc behind, the scattering region.
