  We present Keck Interferometer observations of TW Hya that spatially resolve
its emission at 2 micron wavelength. Analyzing these data together with
existing K-band veiling and near-infrared photometric measurements, we conclude
that the inner disk consists of optically thin, sub-micron-sized dust extending
from ~4 AU to within 0.06 AU of the central star. The inner disk edge may be
magnetospherically truncated. Even if we account for the presence of gas in the
inner disk, these small dust grains have survival times against radiation
blow-out that are orders of magnitude shorter than the age of the system,
suggesting continual replenishment through collisions of larger bodies.
