  We report on a compact and spectrally intense extreme-ultraviolet (XUV)
source, which is based on high-harmonic generation (HHG) driven by 395 nm
pulses. In order to minimize the XUV virtual source size and to maximize the
XUV flux, HHG is performed several Rayleigh lengths away from the driving laser
focal plane in a high-density gas jet. As a result, a high focused XUV
intensity of $5 \times 10^{13}$ W/cm$^2$ is achieved, using a beamline with a
length of only two meters and a modest driving laser pulse energy of 3 mJ. The
high XUV intensity is demonstrated by performing a nonlinear ionization
experiment in argon, using an XUV spectrum that is dominated by a single
harmonic at 22 eV. Ion charge states up to Ar$^{3+}$ are observed, which
requires the absorption of at least four XUV photons. The high XUV intensity
and the narrow bandwidth are ideally suited for a variety of applications
including photoelectron spectroscopy, the coherent control of resonant
transitions and the imaging of nanoscale structures.
