  We demonstrate fully phase matched high-order harmonic generation with
emission spanning the water window spectral region important for bio- and
nano-imaging and a breadth of materials and molecular dynamics studies. We also
generate the broadest bright coherent bandwidth (~300eV) to date obtained from
any light source, small or large. The harmonic photon flux at 0.5 keV is 10^3
higher than demonstrated previously, making it possible for the first time to
demonstrate spatial coherence in the water window. The continuum emission is
consistent with a single attosecond burst, that extends bright attosecond
pulses into the soft x-ray region.
